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Circulation: Arrhythmia and Electrophysiology On the Beat

Paul J. Wang, MD

Each podcast will include key highlights from the journal's current issue and a report on new research published in the field of arrhythmia and electrophysiology.
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Circulation: Arrhythmia and Electrophysiology January 2020 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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04/03/20 • 16 min

Paul J. Wang: Welcome to the monthly podcast On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief with some of the key highlights from this month's issue.

In our first paper in the real time mapping of AF drivers RADAR study, Subbarao Choudry and associates examined in a single arm first in human investigator-initiated FDA IDE study, a novel system for real time, high resolution identification of atrial fibrillation, AF drivers, in persistent or long-standing persistent AF. They enrolled 64 subjects at four centers, 73% male age, 64.7 years, BMI 31.7. LA size 54. Longstanding AF, 83% longstanding persistent, 17%. prior AF ablation, 41%. After 12.6 months of follow-up, 68% remained AF free off all antiarrhythmics. 74% remained AF free and 66% remained AF, AT and A-flutter free on or off antiarrhythmic drugs. AF terminated with atrial fibrillation ablation in 35 patients, 55% overall. And in 23 out of 38, 61% of de novo ablation patients. For patients with AF termination during atrial ablation, 82% remained AF free and 74% AF, AT or A-flutter free during follow-up on or off antiarrhythmic drugs. Patients undergoing first time AFib ablation had higher rates of freedom from AF than the redo group.

In our next paper, David Briceño and associates examined 19 consecutive patients presenting with left bundle branch block ventricular tachycardia in the setting of arrhythmogenic right ventricular cardiomyopathy, ARVC, with procedures separated by at least nine months and a mean of 50 months. The authors found there was no significant progression of voltage bipolar 38 centimeters squared versus 53 centimeters squared, p=0.09 or unipolar 116 centimeters squared versus 159 centimeters squared, p=0.36 for the entire group. There was a significant increase in right ventricular RV volumes, percentage increase 28%. 206 milliliters versus 263 milliliters, P less than 0.001 for the entire study population. Larger scars at baseline but not changes over time were associated with a significant increase in RV volume, p=0.006 for bipolar and p=0.03 for unipolar.

Most patients with progressive RV dilatation, 57%, had moderate in two patients or severe in six patients, tricuspid regurgitation recorded either at initial or repeat ablation procedure. The authors found that in patients with ARVC presenting with recurrent ventricular tachycardia, more than 10% increase in right ventricular endocardial surface area of bipolar voltages consistent with scar is uncommon during intermediate follow-up. Most recurrent ventricular tachycardias are localized to regions of prior defined scar.

In our next paper, Susan Heckbert and associates examined detection of atrial fibrillation in 1,556 individuals participating in an ancillary study involving ambulatory ECG monitoring part of the cross-sectional analysis in the multiethnic study of atherosclerosis, MESA, a community based cohort study that enrolled 6,814 Americans free of clinically recognized cardiovascular disease in 2000 to 2002. Among 1,556 participants, 41% were white, 25% African American, 21% Hispanic, 14% Chinese, 51% were women mean age 74 years. The prevalence of clinically detected atrial fibrillation after 14.4 years follow-up was 11.3% in whites, 6.6% in African Americans, 7.8% in Hispanics and 9.9% in Chinese and was significantly lower in African Americans than in whites in both unadjusted and risk factor adjusted analyses, p less than 0.001. By contrast, in the same individuals, the proportion of monitor detected atrial fibrillation using a 14-day ambulatory ECG monitor was similar in the four race or ethnic groups. 7.1%, 6.4%, 6.9% and 5.2% compared with white, all p greater than 0.5.

The authors concluded that the prevalence of clinically detected atrial fibrillation was substantially lower in African Americans than white participants with or without adjustments for atrial fibrillation risk factors. However, unbiased atrial fibrillation detection by ambulatory monitoring the same individuals reveal little difference in the proportion with atrial fibrillation by race, ethnicity, supporting the hypothesis of differential detection by race, ethnicity in the clinical recognition of atrial fibrillation.

In our next paper, Maria Teresa Barrio-Lopez and associates examined the presence of epicardial connections between pulmonary veins and other anatomical structures. The authors considered an epicardial connection was present if one, the first pass around the pulmonary vein antrum did not produce pulmonary vein isolation. And two, subsequent atrial activation during pulmonary vein pacing showed that the earliest site was located away from the ablation line and later activation sites were obscured near the ablation line.

Out of the 534 patients included, 72 or 13.5%, were found to have 81 epicardial connections. There was a significant association between the presence of epicardial...

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Circulation: Arrhythmia and Electrophysiology December 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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04/03/20 • 16 min

Paul J. Wang: Welcome to the monthly podcast On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, Editor-in-Chief with some of the key highlights from this month's issue.

In our first paper, Jacob Koruth and Associates examine the ability to produce ablation lesions using pulse field ablation, which is tissue specific and non-thermal in swine compared to radio frequency ablation. All 46 targeted veins were successfully isolated on the first attempt in all cohorts. Pulmonary vein isolation durability was assessed in 28 veins, including the SVC. Durability was higher in the pulsed field ablation bipolar group, 18 out of 20 in the bipolar group, 10 out of 18 in the monopolar group, and 3 out of 6 in the radio frequency group. P = 0.002. Transmit morality rates were similar across groups with evidence of nerve damage only with radiofrequency.

In our next paper, Vivek Reddy and Associates is part of the multicentered first-in-human study, RADIANCE, examine the ability of a novel compliant radio frequency balloon catheter with 10 irrigated flexible electrodes to simultaneously and independently deliver energy. At four sites, 39 patients with paroxysmal atrial fibrillation underwent pulmonary vein isolation using energy delivery simultaneously from all electrodes up to 30 seconds posteriorly, and 60 seconds anteriorly. 152 of 152 targeted pulmonary veins were isolated. 79.6% with a single application. Electrical reconnection occurred in only 7 out of 150 pulmonary veins or 4.7% upon adenosine isoproterenol challenge. Esophageal temperature was monitored in all patients. The esophagus was also mechanically deviated in ten patients. At three months, imaging revealed no pulmonary vein stenosis and early atrial recurrence occurred in only 10 out of 39 or 25.6% of patients.

In our next paper Takeshi Kitamura and Associates examine the effect of substrate based ventricular tachycardia ablation targeting local abnormal ventricular activity on recurrent ventricular fibrillation events in patients with structural heart disease. In a retrospective two center study of a total of 686 patients with incident ventricular tachycardia ablation procedure targeting local abnormal ventricular activity, 21 patients, age 57 years left ventricular ejection fraction 30%, had both ventricular tachycardia and ventricular fibrillation.

A total of 80 ventricular fibrillation events were recorded in the ICD logs, the six months preceding ablation. Complete and partial local abnormal ventricular activity elimination was achieved in 11 or 52%, in 10 or 58% of patients respectively. Catheter ablation was associated with a highly significant reduction in ventricular fibrillation recurrences. P less than 0.0001 which were limited to three or 14 patients at six months. The total number of ventricular events therefore, decreased from 80 to three with a median of 1.0 to 0.0 in the six months prior to and following ablation respectively.

The reduction in ventricular fibrillation events was significantly greater in patients with catheter ablation compared to 21 match controls during a 6- month period preceding and following a baseline assessment. The authors concluded that substrate guided ventricular tachycardia ablation, targeting local abnormal ventricular activity, may be associated with a significant reduction in recurrent ventricular fibrillation, suggesting that ventricular tachycardia and ventricular fibrillation share overlapping arrhythmogenic substrate in patients with structural heart disease.

In our next paper, Feng Hu and Associates examine the effect of right anterior ganglion aided plexi ablation on vagal response during circumferential pulmonary vein isolation. 80 patients with paroxysmal atrial fibrillation who underwent first time ablation were prospectively enrolled and randomly assigned to two groups. Group A (n = 40) circumferential pulmonary vein isolation starting with the right pulmonary veins at the right anterior ganglion plexi site. In group B (n = 40) circumferential pulmonary vein isolation starting with the left pulmonary veins first, and the last ablation site being the right anterior ganglionic plexi site.

During circumferential pulmonary vein isolation, the positive vagal response was observed in only one patient in group A, in 25 patients in group B. P less than 0.001. A total of 21 patients with positive vagal response in group B needed temporary ventricular pacing during the procedure, while the only patient with positive vagal response in group A did not need temporary ventricular pacing, P less than 0.001. Compared with baseline basic cycle length, sinus node recovery time, and AV node Wenckebach pacing cycle length were decreased significantly after pulmonary vein isolation procedure in both groups, all P less than 0.05 and without differences between the two groups.

In our next paper, Karl-Heinz Kuck and Associat...

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Circulation: Arrhythmia and Electrophysiology November 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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11/19/19 • 15 min

Dr Paul Wang: Welcome to the monthly podcast, On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief, with some of the key highlights from this month's issue.

In our first paper, Leroy Joseph and associates examined whether an increase in dietary saturated fat could lead to abnormalities of calcium homeostasis and heart rhythm, by an NADPH oxidase 2, NOX2-dependent mechanism.

In mice on high fat diets, they found that saturated fat activates NOX, whereas polyunsaturated fat does not. The high saturated fat diet increased repolarization heterogeneity in ventricular tachycardia, VT inducibility in perfused hearts. Pharmacologic inhibition or genetic deletion of NOX2 prevented arrhythmogenic abnormalities in vivo during high saturated fat diet and resulted in less inducible VT. On the other hand, high saturated fat diet activates calcium calmodulin dependent protein kinase in the heart, which contributes to abnormal calcium handling, promoting arrhythmia. This work suggests that a molecular mechanism links cardiac metabolism to arrhythmia and it suggest that NOX2 inhibitors could be a novel therapy for heart rhythm abnormalities caused by cardiac lipid overload.

In our next paper, Misha Regouski and associates examined whether the relationship between endurance exercise and atrial fibrillation, or AF, is dependent on atrial myopathy. They examined six cardiac specific TGFβ1 transgenic and six wild type goats. Pacemakers were implanted in all animals for continuous arrhythmia monitoring and AF inducibility. AF inducibility was evaluated using five separate ten second bursts of atrial pacing. At baseline sustained AF greater than 30 seconds was induced with 10 seconds of atrial pacing in 4 out of 6 transgenic goats, compared to zero out of six wild type controls, P less than 0.05. No spontaneous AF was observed at baseline, three months of progressive endurance exercise up to 90 minutes at 4.5 miles per hour was performed. The authors observed that between two to three months of exercise, three out of six transgenic animals developed self-terminating spontaneous atrial fibrillation compared to zero out of six wild type animals, (P less than 0.05). There was an increase in AF inducibility in both transgenic and wild type animals during the first two months of exercise with partial normalization at three months.

These changes in AF susceptibility were associated with a decrease in circulating micro RNA 21 and micro RNA 29 during the first two months of exercise, with partial normalization three months in both transgenic and wild type animals. The authors concluded that endurance exercise appears to increase inducible AF secondary to altered expression of key profibrotic biomarkers that is independent of the presence of an atrial myopathy.

In our next paper, Seokhun Yang and associates examined whether there is an association between lifetime exposure to endogenous sex hormone, and incident atrial fibrillation, or AF, in subsequent ischemic stroke. They studied nearly five million natural postmenopausal women aged 40 years or greater without prior history of AF and with breast cancer. The primary end point was incident AF and the secondary end point was subsequent ischemic stroke once AF is developed. During the mean follow up of 6.3 years, shorter total reproductive years (<30 years) was associated with 7% increased risk of AF after adjusting for confounding variables. Adjusted hazard ratio, 1.07. Risk of AF declined progressively with every five-year increment in total reproductive years. P for trend less than 0.001. However, the prolonged, two years or greater use of hormone replacement therapy after menopause was paradoxically associated with a 3% increase in AF risk. (Adjusted ratio 1.03).

For the secondary endpoint analysis, the risk of ischemic stroke after AF development significantly decreased with each five-year increment in total reproductive years with less than 30 years as a reference. (Adjusted hazard ratio 0.93, for 30 to 34 years 0.84, for 35 to 39 years is 0.88, for 40 years or greater. P for trend less than 0.001) the authors concluded that women with natural menopause shortened lifetime exposure to endogenous sex hormone, that is, shorter total reproductive years, was significantly associated with a higher risk of AF and subsequent ischemic stroke. In contrast, prolonged exogenous hormone replacement therapy increased the risk of incident AF.

In our next paper, Stephan Hohmann and associates examine the accuracy of electrocardiographic imaging, ECGi, in a closed chest porcine model. A total of 109 endocardial and nine epicardial locations were paced in nine pigs. ECGi predicted the correct chamber of origin in 85% of atrial and 92% of ventricular sites. Lateral locations were predicted in the correct chamber more often than septal location. (97% versus 79% P=0.01) Absolute distances in space bet...

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Circulation: Arrhythmia and Electrophysiology October 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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10/21/19 • 16 min

Dr Paul Wang: Welcome to the monthly podcast, On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief, with some of the key highlights from this month's issue.

In our first paper, in a single‐center observational cohort study, Owen Donnellan and Associates compared arrhythmia recurrence rates in morbidly obese patients who underwent prior bariatric surgery, with those of non-obese patients following atrial fibrillation ablation. In addition to morbidly obese patients who did not undergo bariatric surgery, they matched 51 morbidly obese patients' body mass index, 40 kilograms per meter squared, who had undergone prior bariatric surgery in a two to one manner with 102 non-obese patients, and 102 morbidly obese patients without bariatric surgery on the basis of age, gender, and timing of atrial fibrillation ablation. From the time of bariatric surgery to ablation, bariatric surgery was associated with a significant reduction in BMI. 47.6 to 36.7 and reduction in systolic blood pressure, 145 to 118, P < 0.001.

During a mean follow up of 29 months following ablation, recurrent arrhythmia occurred in 10 out of 51 or 20 patients in a bariatric surgery group, compared to 25 out of 102 patients, 24.5% in a non-obese group, and 56 out of 102 or 55% in the non-bariatric surgery morbidly obese group. No procedural complications were observed in the bariatric surgery group. In our next paper, Martin Andreas and Associates examined whether noninvasive, low-level, transcutaneous electrical stimulation of the greater auricular nerve reduced the risk of postoperative atrial fibrillation, in a pilot of patients undergoing cardiac surgery. After cardiac surgery, electrodes were applied in the triangular fossa of the ear. Stimulation, amplitude 1-million-amp frequency, one Hertz for 40 minutes, followed by a 20-minute break, was performed for up to two weeks after cardiac surgery. Patients were randomized into sham, N equals 20 or treatment group, N equals 20, for low- level, transcutaneous electrical stimulation. Patients receiving low-level, transcutaneous stimulation had a significant reduced incidence of postoperative atrial fibrillation. Four out of 20, compared to controls 11 out of 20. P equals 0.02.

The median duration of postoperative atrial fibrillation was comparable between the treatment group and control group. No effect on low-level stimulation on CRP or IL-6 levels was detectable. In our next paper, Kazuki Iso and Associates examine whether the vagal response phenomenon is common to patients without atrial fibrillation. Continuous, high- frequent stimulation of the left atrial ganglion and plexus was performed in 42 patients, undergoing ablation for atrial fibrillation. In 21 patients undergoing ablation for left-sided accessory pathway, the high frequency stimulation, 20 Hertz at 25 milliamps of 10 millisecond pulse duration, was applied for five seconds at three sites within the presumed anatomical area of each of the five major left atrial ganglion plexus, for a total of 15 sites per patient. The authors define vagal response to high frequency stimulation, as prolongation of the R interval by > 50% in comparison to the mean pre-high-frequency stimulation RR interval, average over 10 beats.

In active ganglion plexus areas, is areas in which vagal response was elicited. Overall, more active ganglion plexi or GP areas were found in the atrial fibrillation group patients, than in the non-atrial fibrillation group patients. And in all five major GPS, the maximum R interval during high-frequency stimulation was significantly prolonged in atrial fibrillation patients. After multivariate adjustment, association was established between the total number of vagal response sites and the presence of atrial fibrillation. The authors concluded that the significant increase in vagal responses elicited in patients with atrial fibrillation, compared to responses in non-atrial fibrillation patients, suggests that the vagal responses is to hypercan stimulations, reflect an abnormally increased ganglion plexi activity, specific to atrial fibrillation substrates.

In our next paper, Vidal Essebag and Associates combine the data from the Bruise Control One and Two studies to evaluate the effect of concomitant antiplatelet therapy on clinically significant hematomas, and to understand the relative risk of clinically significant hematomas in patients treated with DOAC versus continued Warfarin. The Bruise Control study demonstrated that perioperative Warfarin continuation, reduced clinically- significant hematomas by 80%, compared to Heparin bridging. 3.5% versus 16%. Bruise Control Two observed a similarly low risk of clinically-significant hematomas when comparing continued versus interrupted direct oral anticoagulant. 2.1% in both groups. A total of 1,343 patients were included in Bruise Control One and Bruise Control Two, the primary out...

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Circulation: Arrhythmia and Electrophysiology September 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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09/19/19 • 14 min

Dr Wang: Welcome to the monthly podcast, On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, Editor-in-Chief, with some of the key highlights from this month's issue.

In our first paper, Ying Tian and associates examine the effects and long-term outcomes of percutaneous stellate ganglion blockade in the setting of drug refractory electrical storm due to ventricular arrhythmia. They studied 30 consecutive patients over nearly a five-year period. They used bupivacaine alone, or in combination with lidocaine injected into the neck with good local anesthetic spread in the vicinity of the left stellate ganglion in 15 patients, or both stellate ganglion in 15 patients.

The mean left ventricular ejection fraction was 34%. At 24 hours, 60% of patients were free of ventricular arrhythmia. Patients whose ventricular arrhythmia was controlled had a lower hospital mortality rate than patients whose ventricular arrhythmia continued. 5.6 versus 50%, P equals 0.009. Implantable cardioverter-defibrillator interrogation showed a significant 92% reduction in ventricular arrhythmia episodes from 26 to 2 in the 72 hours after stellate ganglion blockade, P less than 0.001.

Patients who died during the same hospitalization, N equals 7, were more likely to have ischemic cardiomyopathy, 100% versus 43.5%. And recurrent ventricular arrhythmias within 24 hours, 85.7% versus 26.1%. There were no procedure related complications.

In our next paper, Zachi Attia and associates hypothesized that a convolutional neural network could be trained through a process called 'deep learning' to predict a person's age and gender using only 12-lead electrocardiogram signals. They trained convolutional neural network using 10 second samples of 12-lead ECG signals from 499,727 patients to predict gender and age. The networks were tested on a separate cohort of 275,056 patients. For gender classification, the model obtained 90.4% classification accuracy with an area under the curve of 0.97. In the independent test data, age was estimated as a continuous variable with an average error of 6.9 years, R squared equals 0.7.

Among 100 hundred patients with multiple ECGs over the course of at least two decades of life, most patients, 51%, had an average error between real age and convolutional neural network predicted age of less than seven years. Major factors seen amongst patients with convolutional neural network predicted age that exceeded chronologic age by greater than seven years included low ejection fraction, hypertension, and coronary disease, P less than 0.1. In the 27% of patients whose correlation was greater than 0.8, between convolutional neural network predicted and chronological age, no incident events occurred over follow up 30 years.

The authors concluded that applying artificial intelligence to the ECG allows prediction of patient, gender, and estimation of age. The ability of artificial intelligent algorithm to determine physiological age with further validation may serve as a measure of overall health.

In our next paper, Zain Ul Abideen Asad and associates performed a meta-analysis of randomized control trials in order to compare the efficacy and safety of catheter ablation with medical therapy for atrial fibrillation with the primary outcome being all-cause mortality. They examined 18 randomized controlled trials comprising 4,464 patients. Catheter ablation resulted in significant reduction in all-cause mortality, relative risk of 0.69 that was driven by patients with atrial fibrillation and heart failure in reduced ejection fraction, relative risk 0.52.

Catheter ablation resulted in significantly fewer cardiovascular hospitalizations, hazard ratio of 0.56, and fewer recurrences of atrial arrhythmia, relative risk 0.42. Subgroup analysis suggested that younger patients, age less than 65 years, and men derived more benefit from catheter ablation compared to medical therapy.

In our next paper, Felipe Kazmirczak, Ko-Hsuan Amy Chen, and associates examined patients with cardiac sarcoidosis meeting guideline criteria for implantable defibrillator implantation in a large retrospective cohort study of patients with biopsy proven sarcoidosis and known or suspected cardiac sarcoidosis undergoing cardiovascular magnetic resonance imaging. The authors found that in 290 patients, the class one and class 2A recommendation identified all patients who experienced a composite endpoint of significant ventricular arrhythmia or sudden cardiac death over a mean follow-up of three years.

Patients meeting class one recommendations had a significantly higher incidence of composite endpoint than those meeting class 2A recommendations. Left ventricular ejection fraction greater than 35% with greater than 5.7% late gadolinium enhancement and cardiovascular negative residence imaging was as sensitive as or significantly more specific than left tri...

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Circulation: Arrhythmia and Electrophysiology August 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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08/27/19 • 13 min

Dr Paul Wang: Welcome to the monthly podcast, On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, Editor-in-Chief, with some of the key highlights from this month's issue.

In our first paper, Mark McCauley, Flavia Vitale and associates report that carbon nanotube fibers may improve impaired myocardial conduction. In three sheep, radiofrequency ablation was used to create epicardial conduction delay. In addition, in a rodent model, carbon nanotube fibers were sewn across the atrial ventricular junction. They demonstrated acute ventricular preexcitation, but in chronic studies at four weeks, atrial pacing was required for resumption of AV conduction. Carbon nanotube fibers are conductive, biocompatible with no gross or histopathological evidence of toxicity.

In our next paper, Koichiro Ejima and associates compared outcomes of circumferential pulmonary vein isolation for atrial fibrillation ablation randomized to contact force monitoring or unipolar signal modification in 136 patients with paroxysmal atrial fibrillation. In the unipolar signal modification-guided group, each radiofrequency application was delivered until the development of completely positive unipolar electrograms. In the contact force monitoring-guided group, a contact force of 20 grams, ranged 10 to 30 grams, and a minimum force time integral of 400 gram seconds were the targets for each radiofrequency application. The freedom from atrial tachyarrhythmia recurrence at 12 months was 85% in the unipolar signal modification-guided group and 70% in the contact force monitoring-guided group, P equals 0.031. The radiofrequency time for pulmonary vein isolation was shorter in the unipolar signal modification-guided group than contact force monitoring-guided group, but was not statistically significant, P equals 0.077. The incidence of time-dependent in ATP-provoked early electrical reconnections between the left atrium and pulmonary veins, procedural time, fluoroscopic time, and average force-time integral did not significantly differ between the two groups.

In our next paper, Vishal Luther and associates tested whether ripple mapping is superior to conventional annotation-based local activation time mapping for atrial tachycardia diagnosis. Patients with atrial tachycardia were randomized, either ripple mapping or local activation time mapping. The primary endpoint was atrial tachycardia termination with delivery of the planned ablation lesion set. The inability to terminate atrial tachycardia with the first lesion set, the use of more than one entrainment maneuver, or the need to cross over to the other mapping arm were defined as failure to achieve the primary endpoint. The primary endpoint occurred in 38 of 42 patients or 90% in the ripple mapping group, and 29 of 41 patients, 71%, in the local activation time mapping group, P equals 0.45. The primary endpoint was achieved without any entrainment in 31 out of 42 patients or 74% with ripple mapping, and 18 out of 41 patients or 44% with local activation time mapping, P equals 0.01. Of those patients who failed to achieve the primary endpoint, atrial tachycardia termination was achieved in 9 out of 12 patients or 75% in the local activation time mapping group following crossover to ripple mapping with entrainment, but zero out of four patients, 0%, in ripple mapping group crossing over to local activation time mapping with entrainment, P equals 0.04.

In our next paper, Franziska Fochler and associates examined whether anatomical targeting of late gadolinium enhancement MRI-detected gaps and superficial atrial scar is feasible and effective to treat recurrent atrial arrhythmias post-atrial fibrillation ablation. The authors studied 102 patients who underwent initial atrial fibrillation ablation and repeat ablation for recurrent atrial arrhythmias within one-year. 46 patients or 45% with atrial fibrillation recurrence were assigned to group one and underwent fibrosis homogenization as the second procedure. 56 patients or 55% with atrial tachycardia recurrence were assigned to group two and underwent late gadolinium enhancement MRI detected scar-based dechanneling. Both groups underwent re-isolation of pulmonary veins, if necessary.

In the first 25 patients from group two, the atrial tachycardia was electroanatomically mapped and a critical isthmus was defined. It was found that those isthmi were located in the regions with non-transmural scarring detected by late gadolinium enhancement MRI. In the last 31 patients from group 2, an empirical late gadolinium enhancement MRI-based dechanneling was performed solely based on late gadolinium enhancement MRI results. During one-year follow-up after the second ablation, 67% of patients group one and 64% of patients group two were free from occurrence. In group two, 64% in the electroanatomic-guided and 65% in the late gadolinium enhancement MRI dechanneling group were free from ...

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Circulation: Arrhythmia and Electrophysiology July 2018 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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07/15/19 • 15 min

Paul Wang: Welcome to the monthly podcast On The Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr. Paul Wang, editor in chief, with some of the key highlights from this month's issue.

In our first paper, Moo-Nyun Jin, Tae-Hoon Kim, and associates examined the 1-year serial changes in cognitive function, with or without atrial fibrillation catheter ablation. They used the Montreal cognitive assessment score in 308 patients undergoing atrial fibrillation ablation, the ablation group and 50 atrial fibrillation patients on medical therapy who met the same indication for atrial fibrillation ablation, the control group at baseline three months and 12 months. Cognitive impairment was defined as a published cutoff score of less than 23 points. Pre-ablation cognitive impairment was a detected in 18.5%. The Montreal cognitive assessment score significantly improved one year after radio frequency ablation. In both the overall ablation group, 24.9 to 26.4 p less than 0.001, and the propensity matched ablation group 25.4 to 26.5, but not in the control group. 25.4 to 24.8 p equals 0.012. Pre-ablation cognitive pyramid odds ratio 13.7, was independently associated with an improvement in one-year post ablation cognitive function.

In our next paper, Zian Tseng, James Salazar and associates studied World Health Organization defined sudden cardiac deaths autopsied in the POstmortem Systemic InvesTigation of sudden cardiac death, the POST SCD study to determine whether premortem characteristics could identify autopsy defined sudden arrhythmic death among presumed sudden cardiac deaths. They prospectively identified 615 World Health Organization defined sudden cardiac deaths, of which 144 were witnessed. Autopsy defined sudden arrhythmic death had no extra cardiac or acute heart failure cause of death. Of the 615 presumed sudden critic deaths, 348 or 57% were autopsy defined, sudden arrhythmic deaths. For witness cases, using an emergency medical system model area under the receiver operator curve 0.75, included presenting rhythm of ventricular tech or cardiac fibrillation, pulseless electrical activity, while the comprehensive model, adding medical record data and depression, area under the curve 0.78. If only VTVF witness cases, 48 of those were classified as sudden arrhythmic death. The sensitivity was 0.46, and specificity 0.90.

For unwitnessed cases, the emergency medical system model, area under the curve 0.68, included black race, male sex, age, time since last seen normal, while the comprehensive, area into the curve 0.75, added the use of beta blockers, antidepressants, QT prolonging drugs, opiates, illicit drugs and dyslipidemia. If only unwitnessed cases, less than one hour, n equals 59, were classified as sudden arrhythmic deaths, the sensitivities were 0.18, and specificity was 0.95. The authors concluded that models could identify pre-mortem characteristics to better specify autopsy defined sudden arrhythmic deaths, among presumed sudden cardiac arrests. The authors suggest that the World Health Organization definition can be improved by restricting witnessed sudden cardiac deaths to ventricular tachycardia fibrillation or non-pulseless electrical activity rhythms in unwitnessed cases to less than one hour since last normal, at a cost of sensitivity.

In our next paper, Rafael Jaimes III and associates performed optical mapping of trends, membrane, voltage and pacing studies on isolated Langendorff-perfused rat hearts to assess the cardiac electrophysiology after mono-2-ethylhexyl phthalate, a phthalate with documented exposure in intensive care patients. The authors found that a 30-minute exposure to mono-2-ethylhexyl phthalate increased the atrioventricular node effector in period 147 milliseconds compared to 170 milliseconds in controls and increased the ventricular effective refractory periods of 117 milliseconds compared to 77.5 milliseconds in controls. Optical mapping revealed prolonged action potential duration at slower pacing cycle lengths. Mono-2-ethylhexyl phthalate exposure also slowed epicardial conduction velocity, 25 centimeters per second compared to 60 centimeters per second in controls. The authors concluded that acute mono-2-ethylhexyl phthalate exposure, at clinically relevant doses, has a significant effect on cardiac electrophysiology in the intact heart. Heightened clinical exposure to plasticized medical products may have cardiac safety implications and lead to cardiac arrhythmias.

In our next paper, Stephan Willems and associates report the use of a novel, non-contact imaging and mapping system that uses ultrasound to reconstruct atrial chamber anatomy and measure timing and density of dipolar, ionic activation or charge density across the myocardium to guide ablation of atrial arrhythmias. They conducted a prospective non-randomized study, the UNCOVER AF trial which was conducted at 13 centers across Europe and Canada. In 127 pati...

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Circulation: Arrhythmia and Electrophysiology June 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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06/18/19 • 17 min

Dr. Wang: Welcome to the monthly podcast, On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr. Paul Wong, editor-in-chief, with some of the key highlights from this month's issue.

In our first paper, Jeremy Wasserlauf and associates compare the accuracy of an atrial fibrillation sensing smartwatch with simultaneous recordings from an insertable cardiac monitor.

The authors use smart rhythm 2.0, a convolutional neuro-network, trained on anonymized data of heart rate, activity level and EKGs from 7500 AliveCor users.

The network was validated on data collected in 24 patients with insertable cardiac monitor, and a history of paroxysmal atrial fibrillation who simultaneously wore the atrial fibrillation sensing smart watch with smart rhythm 0.1 software.

The primary outcome was sensitivity of the atrial fibrillation sensing smart watch for atrial fibrillation episodes of greater than equal to one hour. Secondary end points include sensitivity of atrial fibrillation sensing smart watch for detection of atrial fibrillation by subject and sensitivity for total duration across all subjects.

Subjects with greater than 50% false positive atrial fibrillation episodes on insertable cardiac monitor were excluded.

The authors analyzed 31,349 hours meaning 11.3 hours per day of simultaneous atrial fibrillation sensing smart watch and insertable cardiac monitor recordings in 24 patients. Insertable cardiac monitor detected 82 episodes of atrial fibrillation of one hour duration or greater while the atrial fibrillation sensing smartwatch was worn. With a total duration of 1,127 hours.

Of these, the smart rhythm 2.0 neural network detected 80 episodes. Episode sensitivity 97.5% with total duration 1,101 hours. Duration sensitivity 97.7%.

Three of the 18 subjects with atrial fibrillation of one hour or greater had atrial fibrillation only when the watch was not being worn. Patient sensitivity 83.3% or 100% during the time worn. Positive predictive value for atrial fibrillation episodes was 39.9%.

The authors concluded that an atrial fibrillation sensing smartwatch is highly sensitive to detection of atrial fibrillation and assessment of atrial fibrillation duration in an ambulatory population when compared to insertable cardiac monitor.

In our next paper, Liliana Tavares and associates examine the autonomic nervous system response to apnea in its mechanistic connection to atrial fibrillation. They study the effects of ablation of cardiac sensory neurons with resiniferatoxin, a neurotoxic transient receptor potential vanilloid one agonist.

In a canine model, apnea was induced by stopping ventilation until oxygen saturation decreased in 90%. Nerve recordings from bilateral vagal nerves left stellate ganglion and anterior right ganglion plexi were obtained before and during apnea, before and after resiniferatoxin injection in the anterior white ganglion plexi in seven animals.

Each refractory period and atrial fibrillation inducibility upon single extra stimulation was assessed before and during apnea, before and after intrapericardial resiniferatoxin administration in nine animals.

The authors found that apnea increased anterior wide ganglion plexi activity followed by cluster crescendo vagal bursts synchronized with heart rate and blood pressure oscillation.

Upon further oxygen desaturation, a tonic increase in left stellate ganglion activity in blood pressure oscillations ensued. Apnea induced atrial effective refractory shortening from 110 to 90 milliseconds, P less than 0.001 and atrial fibrillation induction in nine animals vs. zero out of nine at baseline.

After resiniferatoxin administration increases in ganglion plexi and left stellate ganglion activity, and blood pressure during apnea were abolished, in addition, the atrial effector refractory period increased to 127 milliseconds, P=0.0001 and atrial fibrillation was not induced.

Vagal bursts remain unchanged. Ganglion plexi cells showed cytoplasmic microvacuolation and apoptosis. The authors concluded that apnea increased ganglion plexi activity followed by vagal bursts and tonic left stellate ganglion firing. Resiniferatoxin decreases sympathetic and ganglion plexi nerve activity, abolishes apnea's electrophysiotic response and atrial fibrillation inducibility indicating that sensory neurons play a role in apnea induced atrial fibrillation.

In our next paper, Thomas Pambrun and associates examined whether using unipolar signal modification as a local end point would improve the safety and efficacy of high-power ablation during pulmonary vein isolation. They studied four swine and 100 consecutive patients referred for pulmonary vein isolation with the first 50 patients in a control group using 25 to 30 watts and the last 50 patients in a study group with 40 to 50 watts.

Atrial radiofrequency...

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Circulation: Arrhythmia and Electrophysiology May 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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05/21/19 • 11 min

Dr Paul Wang: Welcome to the monthly podcast, On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor-in-chief, with some of the key highlights from this month's issue.

In our first article, Daniel Alyesh, Konstantinos Siontis and associates described myocardial calcifications in patients with ischemic cardiomyopathy undergoing ventricular tachycardia ablation in comparison to a control group of patients without ventricular tachycardia. They found that in 56 consecutive post-infarction patients, myocardial calcifications were identified in 39 or 70% of post-infarction ventricular tachycardia patients compared to 6 or 11% of patients without ventricular tachycardia. A calcification volume of 0.538 centimeters cube distinguished patients with calcification-associated ventricular tachycardia from patients without calcification-associated ventricular tachycardias; area under the curve, 0.87; sensitivity, 0.87; specificity, 0.88. A non-confluent calcification pattern was associated with ventricular tachycardia target sites independent of calcification volume, P equals 0.01. Myocardial calcifications corresponding to areas of electrical non-excitability forming a border for re-entry were found in 33% of all ventricular tachycardias for which target sites were identified, and in 62% of patients with myocardial calcifications.

In our next paper, Mia Fangel and associates examined whether glycemic status evaluated by hemoglobin A1c has an effect on the risk of thromboembolism among patients with atrial fibrillation and Type 2 diabetes. They used a cohort study from 5,386 patients with incident non-valvular atrial fibrillation and Type 2 diabetes in Danish registries. Compared with patients with hemoglobin A1c of less than or equal to 48 millimole per mole, they observed a higher risk of thromboembolism among patients with hemoglobin A1c 49 to 58 millimoles per mole with a hazard ratio of 1.49 and a hemoglobin A1c greater than 58 millimole per mole with a hazard ratio of 1.59 after adjusting for confounding factors. Surprisingly, in patients with diabetes duration of 10 years or more, higher hemoglobin A1c levels were not associated with a higher risk of thromboembolism.

In our next paper, Niek Beurskens and associates compared tricuspid valve dysfunction in leadless pacemaker therapy to dual chamber transvenous pacing systems. They studied 53 patients receiving a leadless pacemaker, including 28 with a Nanostim and 25 with a Micra device. Of these 53 patients, 23 or 43% had tricuspid regurgitation that was graded as being more severe at 12 months. Compared with an apical position, a right ventricular septal position of the leadless pacemaker was associated with increased tricuspid valve incompetence, odds ratio, 5.20; P equals 0.03. An increase in mitral valve regurgitation was observed in 38% of patients. Leadless pacemaker implantation resulted in a reduction of right ventricular function. Leadless pacemaker implantation was further associated with a reduction in left ventricular ejection fraction and elevated LV TI index. The changes in tricuspid regurgitation in leadless pacing group was similar to the changes in dual-chamber transvenous pacemaker group, 43% versus 38% respectively; P equals 0.39.

In our next paper, Jurgen Duchenne and associates examined whether regional left ventricular glucose metabolism correlates with regional work in an animal model with reversible dyssynchrony due to pacing. In 12 sheep, after 8 weeks of right atrial and right ventricular free wall pacing, there is evidence of left ventricular dilatation and thinning of the septum and thickening of the lateral wall. The authors employed motion compensation and anatomical correction in order to provide reliable regional estimates of myocardial glucose metabolism. They found that in homogenous regional distribution of myocardial workload due to left bundle branch block triggers adaptive remodeling of the left ventricle, leading to a more homogenous load distribution per volume unit myocardium. In reverse, cardiac resynchronization therapy leads acutely to an inhomogeneous distribution of workload, which homogenizes over time due to reverse remodeling. The authors concluded that redistribution of regional loading appears as a mode of action of cardiac resynchronization therapy so that myocardial mechanics should be the main treatment target of cardiac resynchronization therapy.

In our next paper, Jihye Jang and associates examined the association between local conduction velocity and late gadolinium enhancement and myocardial thickness in a swine model of healed left ventricular infarction. They studied six swine with healed myocardial infarction and two controls. The authors found a significantly slower conduction was found in late gadolinium enhancement regions, 0.33 versus 0.54 meters per second, P less than 0.001, and regions of wall thinning, 0.38 versus 0....

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Circulation: Arrhythmia and Electrophysiology February 2020 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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04/09/20 • 12 min

Paul J. Wang: Welcome to the monthly podcast On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief, with some of the key highlights from this month's issue.

In our first paper, Ling Kuo and associates examine the association between left atrial high-resolution late gadolinium enhancement on cardiac magnetic resonance and electrogram abnormalities in patients with atrial fibrillation or AF. They found that in 40 AF patients age 63.2 years with a mean of 1312 electrogram points per patient. Lower bipolar voltage was associated with higher signal intensity Z score in patients who had undergone previous ablation coefficient equals -0.049 P < 0.001 but not in ablation-naive patients, coefficient = -0.004, P = 0.7. Left atrial high-resolution late gadolinium enhancement activation delay was associated with signal intensity z-score in patients with previous ablation, signal intensity Z score coefficient = 0.004, P < 0.001 but not in ablation-naive patients. In contrast, increased left atrial high-resolution late gadolinium enhancement fractionation was associated with signal intensity z-score coefficient 0.012, P = 0.03, and left atrial high-resolution late gadolinium enhancement coefficient 0.035, P < 0.001 only in ablation-naive patients.

The authors concluded that the association of left atrial late gadolinium enhancement with voltage is modified by ablation in ablation naive patients. Atrial late gadolinium enhancement is associated with electrogram fractionation even in the absence of voltage abnormality.

In our next paper, Laila Staerk and associates examine the associations between 85 protein biomarkers and incident atrial fibrillation or AF in patients 50 years of age or greater, from the Framingham Heart Study Offspring and Third Generation cohorts. Out of 3378 participants, 54% women, mean age 61.5 years, 401 developed AAF over a mean follow-up of 12.3 years. They observed a lower hazard of incident atrial fibrillation associated with mean higher levels of incident like growth factor hazard ratio per one standard deviation increment in protein level equals 0.84, and higher hazard ratio of incident atrial fibrillation associated with higher mean levels of both insulin-like growth factor-binding protein and N-terminal pro-B-hormone type a natriuretic peptide.

In our next paper, Eoin Donnellan and associates examine changes in atrial fibrillation or AF type following bariatric surgery in 220 morbidly obese patients body mass index ≥40 kilograms per meter square. They observed a reduction in body mass index following bariatric surgery from 49.7 to 37.2 kilograms per meter square. Weight loss was greatest in the gastric bypass group with a mean percentage loss of 25% compared to 19% in patients underwent sleeve gastrectomy, and 16% following gastric banding. P < 0.0001 reversal of AF type occurred in 71% of patients following gastric bypass, 56% of patients who underwent sleeve gastrectomy and 50% of patients following gastric banding, P = 0.004. They found that on Cox proportional hazards analysis percent weight loss was significantly associated with AFib reversal, P = 0.0002.

In our next paper, Thomas Pezawas and associates examine the role of diastolic function assessment to predict arrhythmic death.

They prospectively enrolled 120 patients with ischemic, 60 patients with dilated cardiomyopathy, and 30 patients with normal left ventricular ejection fraction. After an average of 7.0 years, arrhythmic death or resuscitated cardiac arrest was observed in 28 (or 13.3%) and 33 (or 15.7%) of patients respectively. Non-arrhythmic death was found in 41 (or 19.5%) of patients. On Kaplan Meier analysis patients with dysfunction grade III had the highest risk of arrhythmic death or resuscitated cardiac arrest, P < 0.001.

This finding was independent from the degree of left ventricular ejection fraction and was observed in patients with ejection fraction ≤ 35%, P = 0.001 and with a left ejection fraction > 35%, P = 0.014. Non-arrhythmic mortality was highest and patients with dysfunction grade III. This was true for patients with left ventricular ejection fraction ≤to 35%, or > 35%. In an adjusted model for relevant confounding factors, grade III dysfunction was associated with a 3.5-fold, increased risk of arrhythmic death or resuscitated cardiac arrest in the overall study population hazard ratio of 3.52, P < 0.001.

In our next paper, because asthma and atrial fibrillation share an underlying inflammatory pathophysiology, Matthew Tattersall and associates hypothesize that persistent asthmatics would be at higher risk for developing atrial fibrillation or AF and this association would it be attenuated by adjust for baseline markers of systemic inflammation.

The autho...

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How many episodes does Circulation: Arrhythmia and Electrophysiology On the Beat have?

Circulation: Arrhythmia and Electrophysiology On the Beat currently has 42 episodes available.

What topics does Circulation: Arrhythmia and Electrophysiology On the Beat cover?

The podcast is about Health & Fitness, Cardiology, Natural Sciences, Medicine, Podcasts and Science.

What is the most popular episode on Circulation: Arrhythmia and Electrophysiology On the Beat?

The episode title 'Circulation: Arrhythmia and Electrophysiology January 2020 Issue' is the most popular.

What is the average episode length on Circulation: Arrhythmia and Electrophysiology On the Beat?

The average episode length on Circulation: Arrhythmia and Electrophysiology On the Beat is 27 minutes.

How often are episodes of Circulation: Arrhythmia and Electrophysiology On the Beat released?

Episodes of Circulation: Arrhythmia and Electrophysiology On the Beat are typically released every 28 days.

When was the first episode of Circulation: Arrhythmia and Electrophysiology On the Beat?

The first episode of Circulation: Arrhythmia and Electrophysiology On the Beat was released on Jun 1, 2017.

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