Circulation: Arrhythmia and Electrophysiology On the Beat

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 this month, Shaan Khurshid and associates determine the frequency of rhythm abnormalities in 502,627 adults in the UK Biobank, a national prospective cohort. They found that 2.35% had a baseline rhythm abnormality. The prevalence increased with age, with 4.84% of individuals aged 65 to 73 years having rhythm abnormalities. During over three million person- years of follow up, nearly 16,000 new rhythm abnormalities were detected. Atrial fibrillation was the most frequent with three per thousand person-years. Bradyarrhythmia with almost one per thousand person-years. Conduction system disease is about one per one thousand years. Supraventricular and ventricular arrhythmias, each about one half per one thousand person-years. Older age was associated with a hazard ratio of 2.35 for each 10 year increase. Male sex, hypertension, chronic kidney disease and heart failure were all associated with new rhythm abnormalities.

In our next paper, Fabien Squara and associates evaluated a method of determining the septal or free wall positioning of pacemaker or ICD leads during fluoroscopy. They compared in 50 patients a classical approach using posterior anterior, right anterior oblique 30 degrees, and left anterior oblique 40 degrees fluoroscopic imaging’s to 50 patients undergoing an individualized left anterior oblique or LAO approach. This individualized LAO approach view provided a true view of the interventricular septum. This angle was defined by the degree of LAO that allowed the perfect superimposition of the RV apex, using the tip of the right ventricular lead, temporarily placed at the apex, and one of the superior vena cava, inferior vena cava access using a guide wire. Transthoracic echo was used to confirm position of the right ventricular lead.

Septal, or free wall, right ventricular lead positioning was correctly identified in 96% of patients in the individualized group, versus 76% in the classical group. P equals 0.004. For septal lead positioning fluoroscopy had 100% sensitivity, and an 89.5 specificity in an individualized group, versus 91.4% sensitivity, and a 40% specificity in the classical group.

In our next paper, Elsayed Soliman and associates examined the lifetime risk of atrial fibrillation based on race and socioeconomic status. In the atherosclerosis risk in communities, ARIC, cohort, of 15,343 participants without atrial fibrillation, patients were recruited in 1987 to 1989, when they were 45 to 64 years of age, and followed through 2014. The authors identify 2,760 atrial fibrillation cases during a mean follow up of 21 years. The authors found that the lifetime risk of atrial fibrillation in the ARIC cohort was approximately one in three among whites, and one in five among African Americans. And, the socioeconomic status was inversely associated with cumulative incidents of atrial fibrillation before the last decades of life.

In our next paper, Jonathan Steinberg and associates sought to determine the impact of atrial fibrillation episode duration threshold on atrial fibrillation incidents and burden in pacemaker patients in a prospective registry. In 615 pacemaker patients was device detected atrial fibrillation over a mean follow up of 3.7 years, 599 had one or more atrial fibrillation episodes of 30 seconds duration, with a mean number of 22 episodes. At 12 months, freedom from atrial fibrillation ranged from 25.5% to 73.1%, based on a duration threshold from 30 seconds up to 24 hours. Of patients with a first episode of 30 seconds to two minutes, 35.8% were free from subsequent episodes greater than two minutes at 180 days. The mean atrial fibrillation burden of 0.2% for patients with first episodes between 30 seconds and 3.8 hours, was significantly less than the 9.5% burden for those with greater than 3.8 hours.

The authors concluded that small differences in atrial fibrillation episode duration definition can significantly affect the perceived incidents of atrial fibrillation impact reported outcomes, including atrial fibrillation success. An initial atrial fibrillation episode of 30 seconds does not predict clinically meaningful atrial fibrillation burden.

In the next paper, Hongwu Chen and Linsheng Shi and associates examined the distinct electrophysiologic features of bundle branch reentrant ventricular tachycardia in patients without structural heart disease. They described nine patients, mean age 29.6 years, with normal left ventricular function and bundle branch reentrant ventricular tachycardia, with a right bundle branch block pattern in one patient, and left bundle branch block patterns in nine patients. In all left bundle branch block pattern ventricular tachycardia, the mean ventricular tachycardia cyc...

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. We'll also hear from Dr. Suraj Kapa, reporting on new research from the latest journal articles in the field.

This month's issue of Circulation: Arrhythmia and Electrophysiology has a number of fascinating and important articles. Let's start with the first article by Philip Halbfass and Associates, which describes the use of esophageal endoscopy in patients undergoing atrial fibrillation ablation. Of 1,802 patients undergoing afib ablation, 832 underwent post-procedural esophageal endoscopy. All patients were ablated using a single tip re-circular ablation catheter. Category one lesions described as erythema erosion were seen in 98 out of these 295 patients, while in 52 out of the 295 patients, ulceration was seen. In three of the 832 patients, esophageal perforation occurred, and in two of the 832 patients, atrial-esophageal fistula occurred.

Esophageal perforation only occurred in patients with category two lesions with an absolute risk of 9.6%. The authors concluded that post-ablation esophageal endoscopy is able to identify patients with high-risk lesions. One out of 10 patients with post-ablation esophageal ulcers progressed to perforation, while no patients without esophageal ulcers showed evidence of perforating complications.

In the next article by Christian Sohns and Associates describes the relationship between atrial fibrosis identified with magnetic resonance imaging and atrial rotor activity identified by noninvasive electrophysiological mapping. Ten patients underwent pulmonary vein isolation for persistent atrial fibrillation. Late gadolinium enhancement using magnetic resonance imaging, which projected onto the anatomy used for noninvasive electrophysiologic mapping.

The noninvasive electrophysiologic mapping identified 410 rotors evenly distributed between the left atrium and the right atrium. This study found that there was no statistically significant association between the presence of late gadolinium enhancement and the presence of rotors.

In the next article written by Jereon Venlet examines the endocardial unipolar voltage that best identifies abnormal epicardial electrograms. Thirty-three patients underwent endocardial epicardial right ventricular electro-anatomical mapping in ablation of right ventricular scar-related ventricular tachycardia. Eighty-six percent of abnormal epicardial electrograms had corresponding endocardial sites with bipolar electrogram less than 1.5 millivolts.

The remaining abnormal epicardial electrograms could be identified by endocardial unipolar voltages of less than 3.7 millivolts. The authors concluded that this use of endocardial unipolar voltage cut off at normal bipolar voltage sites improves the identification of all abnormal epicardial electrograms where there is less than 1 millimeter of fat.

The next article by Alan Bulava and Associates examines the outcomes of hybrid epicardial and endocardial radial frequency ablation, a persistent atrial fibrillation. Seventy patients underwent the epicardial thoracoscopic procedure followed by endocardial mapping ablation two to three months later. At the time of catheter ablation, 76% of patients were in sinus rhythm. All four pulmonary veins were found to be isolated in 69% of the patients and the left atrial posterior wall was isolated in 23% of the patients.

In the 12 months after the catheter ablation, 77% were arrhythmia-free, off antirrhythmic drugs. The majority of arrhythmia occurrences occur during the first 12 months following catheter ablation. Using previously ineffective antiarrythmics drugs and re-ablation procedures, arrhythmia-free survival increased to 97% during a mean followup of 936 days. Left atrial volume greater than 165 milliliters, the absence of sinus rhythm before catheter ablation and induce-ability of any sustained tachyarrhythmia at the end of catheter ablation predicted atrial fibrillation recurrence.

The authors concluded that the majority of patients after epicardial ablation required endocardial catheter ablation to complete the linear ablation or pulmonary vein isolation lesion sets. In the next article, Jason Roberts and Associates studied the clinical phenotype of Type 6 Long QT Syndrome, stemming from mutations in the KCNE2 encoded voltage gated channel beta subunit.

The authors examined individuals reported pathogenic KCNE2 mutations collected from inherited arrhythmia clinics in the Rochester LQTS registry as well as previously reported LQT6 cases identified through a med-line database search. Of 44 probands studied, 16 probands had resting QTC intervals and only developed QT prolongation and malignant arrhythmias following exposure to QT prolonging stressors. Ten had other Long QT pathogen...

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

In our first paper, Parikshit Sharma and associates reported on the use of permanent his bundle pacing to improve hemodynamics in 39 patients with right bundle branch block. His bundle pacing was successfully performed in 37, or 95 percent of the patients, and resulted in narrowing of the QRS complex from 158 milliseconds to 127 milliseconds. P = 0.0001. An increase in left ventricular ejection fraction from 31 percent to 39 percent. P = 0.004, an improvement in the New York Heart Association functional class from 2.8 to 2.0 P = 0.0001. This work suggests that his bundle pacing maybe helpful in right bundle branch block patients with left ventricular dysfunction.

In our next paper, Philippe Debruyne and associates added to our understanding of using catheter ablation to modulate the autonomic nervous system in patients with neurally mediated syncope, signs of no dysfunction and functional AV block. Prior reports of autonomic modulation using catheter ablation have required extensive ablation in both atria. In this article, the authors report a significant 95% reduction in syncope at six months as a result of targeted ablation in the right atrium alone, focusing on partial ablation of the interior right ganglionated plexus. Ablation is quite limited, taking a mean of seven minutes and creating a mean surface area of 11 millimeters squared. This technique has promise as a possible treatment for avoiding a need of pacemaker implantation in some patients.

In our next paper, Shankar Baskar and associates examined the characteristics and outcomes of pediatric patients receiving implantable cardioverter defibrillators and compared them to their adult counterparts. They examined ICD recipients in the NCDRICD registry from 2010 to 2016. There were 562,209 total ICD implants, including 3461 pediatric patients. Of the pediatric patients, 60 percent of implants were for primary prevention with non-ischemic cardiomyopathy being present in 60 percent of the patients, the most common underlying disease. Over time, there is an increasing trend of both primary and secondary prevention ICD implantations, P less than 0.05. Compared to adults, pediatric patients were likely to have structural heart disease, hypertrophic cardiomyopathy, ion channelopathy, and to receive a single chamber device. All P less than 0.001. There is no difference in in-hospital complications between the adult and the pediatric cohorts, 2.4 percent versus 2.6 percent. However, among pediatric patients, lower weight, Ebstein's anomaly, worse New York Heart Association class dual chamber and resynchronization defibrillator were associated with greater risk of complications. Although, re-intervention for generator replacement or upgrade was more common in adults, the time to re-intervention was shorter in the pediatric cohort.

In our next paper, Ahmed Hussein and associates examine the effect of using ablation index guiding ablation in 40 patients with persistent HO fibrillation on the rate of pulmonary vein reconnection. Pulmonary vein reconnection was seen as a mandatory repeat electro-physiologic study in 22 percent of patients, effecting seven percent of pulmonary veins. Ablation on the intravenous cryna was required in 44 percent of patients to achieve durable pulmonary vein isolation. Atrial tachyarrhythmia occurrence was documented in eight to 20 percent of patients, only one of whom had pulmonary vein reconnection at repeat study. At 12 months, 30 out of 40, or 95 percent of patients, were in sinus rhythm, with four or 10 percent of patients having starting antiarrhythmic drugs. Higher body mass index and excessive alcohol consumption were the only significant factors associated with atrial tachyarrhythmia occurrence.

In our next paper, Atsushi Hirayama and associates examined whether acute exasperation of chronic obstructive pulmonary disease increases the risk of repeated atrial fibrillation related health care utilization. They examine 944 patients who are hospitalized for acute exasperation of chronic obstructive pulmonary disease and had emergency department visit or hospitalization for atrial fibrillation during a 450 day period. Compared to the reference period, the rate of atrial fibrillation related emergency department visits or hospitalizations significantly increased in the first 90 days after acute exasperation of chronic obstructive pulmonary disease. 7.3 versus 14.1 per one hundred person months, resulting in a risk ratio of 1.93.

In our next paper, Namsik Yoon and associates examined the mechanisms underlying the electrocardiographic and arrhythmic manifestation of experimental models of early repolarization syndrome and the ameliorative effects of radio-frequency ablation....

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 from the Finland Group Registry, Nordenswan and her colleagues have further defined the risk of sudden cardiac death in ventricular arrhythmias in patients with cardiac sarcoidosis. While it has been observed that there's a high risk of lethal arrhythmias in cardiac sarcoidosis patients with high grade AV block, the incidents in these patients with lone AV block, in the absence of known VT or left ventricular dysfunction, has not been described. From the patients with myocardial inflammatory diseases in their registry, the authors identified 143 cardiac sarcoidosis patients with high grade AV block. Of these patients, 90 had lone AV block. For these patients, the five-year composite incidence of sudden cardiac death or VT was 24%, in comparison with 54% in AV block with ventricular tachycardia or severe left ventricular dysfunction, and 24% with AV block in non-severe left ventricular dysfunction.

These findings support implementation of an implantable cardioverter defibrillator for cardiac sarcoidosis patients with lone AV block. A recent study by Gold and Colleagues suggests atrial ventricular optimization improves reverse remodeling in patients with significant intraventricular electrical delay. In this sub-study of the Smart AV Trial, 275 subjects were randomized to either electrogram-based AV optimization, smart delay, or nominal AV delay, 120 milliseconds. In this mostly male cohort, with a mean age of 65 years, and a left ventricular ejection fraction of 28% at follow up, at six months the benefit of AV optimization increased as intraventricular electrical delay prolonged, defined as the time between the peaks of the right and left ventricular electrograms. The longest cohort trial of intraventricular conduction delay had 4.26 times greater odds of remodeling response with AV optimization compared with nominal AV delay. This suggests that the left ventricular lead position in AV optimization might have a synergistic effect in reverse remodeling in cardiac resynchronization patients.

Concerns have long been raised that anorexia nervosa causes QT interval prolongation predisposing these individuals to life-threatening ventricular arrhythmias and sudden cardiac death. Fredrickson and Associates made progress in challenging this conclusion, demonstrating that despite a slightly increased incidence in borderline mean QTC, greater than 440 milliseconds, in 430 female anorexia nervosa patients, compared to 123 healthy controls from the Danish Civil Register, there was no difference in the risk of prolonged corrected QT interval greater than 460 milliseconds between the two groups.

However, during a 10-year follow up, anorexia nervosa patients had a slightly increased risk of ventricular tachycardiac, aborted cardiac arrest, and cardiac arrest compared to healthy controls. Incidence of 0.5% in the anorexia nervosa patients versus 0.07% in healthy controls. In addition, anorexia nervosa patients had a significantly increased risk of all-cause mortality with a hazard ratio of 11.2 over 10 years compared to population-based cohort, suggesting that anorexia nervosa increases the risk of medical complications, including cardiac complications, but these are not directly related to anorexia nervosa's effects on corrected QT interval.

In our next paper, Ahmed Karim Talib and Associates reported on the outcomes of endocardial ablation of drug-resistant ventricular fibrillation in Brugada syndrome. Endocardial mapping ablation was performed in 21 patients with one or more episodes of ventricular fibrillation. Endocardial mapping revealed low voltage fractionated endocardial electrograms in 19% of patients. All patients underwent ablation of ventricular fibrillation triggers, followed by endocardial substrate modification. Noninducibility of ventricular fibrillation and normalization of Brugada ECG was documented in 14, in three patients, respectively. During a mean follow up of 54 months, seven patients, or 33%, experienced ventricular fibrillation recurrences, presence of cruris notching in D1 was associated with the presence of low-voltage fractionated endocardial electrograms in ablation failure.

In our next paper, Jae Yeong Cho and Associates tried to elucidate the mechanism of sudden cardiac death in patients with heart failure with preserved ejection fraction using an ambulatory recording in a rat model. They showed that rats who had a clinical phenotype of heart failure with preserved ejection fraction had prolonged QT and QTC intervals and reduced heart rate variability compared to the controls. Importantly, the rats with heart failure and preserved ejection fraction had significantly higher rates of spontaneous ventricular arrhythmias, and about a t...

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 study, Filip Plesinger and associates examined whether a computerized analysis of the body surface 12-lead ECG can be used to measure the ventricular electrical activation delay as a predictor of heart failure or death following resynchronization therapy in a MADIT-CRT trial.

The authors found that left bundle branch block patients with baseline ventricular electrical activation delay less than 31.2 milliseconds had a 35% risk of MADIT-CRT endpoints, while patients with ventricular electrical activation delay greater than or equal to 31.2 milliseconds had a 14% risk, P value of less than 0.001.

The hazard ratio for predicting primary endpoints in patients with low ventricular electrical activation delay was 2.34 with a P value of less than 0.01. However, ventricular electrical activation delay was not predicted in patients with right bundle branch block or IVCD.

In our next study, Karl-Heinz Kuck and associates examined the predictors of long-term clinical outcomes after catheter ablation of atrial fibrillation in 750 patients in the FIRE AND ICE Trial. Using propensity score stratification methods to count for differences in baseline characteristics between sexes, the authors found that female sex with a hazard ratio of 1.37, P equals 0.01, and prior direct current cardioversion with a hazard ratio of 1.40, P equals 0.013 were independently associated with atrial fibrillation recurrence.

Female sex with hazard ratio of 1.36, P value of 0.035 and hypertension with a hazard ratio of 1.48, P value of 0.013 independently predicted cardiovascular rehospitalization. A longer history of atrial fibrillation with a hazard ratio of 1.03, P value of 0.039 increased the rate of repeat ablation.

After propensity score adjustment, women continued to have higher rates of primary efficacy failure with adjusted hazard ratio of 1.51, P less than 0.05 and cardiovascular rehospitalization with a hazard ratio of 1.40, P less than 0.05.

In the next study, Laura Bear and associates examined the reliability of inverse electrocardiographic mapping of cardiac electrical activity from recorded body surface potentials. In five anesthetized closed-chest pigs, torso and ventricular epicardial potentials were recorded simultaneously during sinus rhythm, epicardial, and endocardial ventricular pacing. Two approaches, coupled finite/boundary element methods and a meshless approach based on the method of fundamental solutions, were compared.

The authors found that inverse mapping underestimated epicardial potentials more than twofold, P less than 0.0001. Mean correlation coefficients for reconstructed epicardial potential distributions ranged from 0.60 to 0.64 across all methods. Epicardial electrograms were recovered with reasonable fidelity at approximately 50% of the sites, but variation was substantial.

General activation spread was reproduced with a mean correlation coefficient of 0.72 to 0.78 for activation time maps with spatio-temporal smoothing. Epicardial foci were identified with a mean location error approximately 16 millimeters. Inverse mapping with method of fundamental solutions was better than coupled finite/boundary element methods.

The authors concluded that spatio-temporal variability of recovered electrograms may limit the resolution, with implications for accuracy of arrhythmia localization.

In the next study, Pejman Raeisi-Giglou and colleagues examined the incidence of pulmonary vein stenosis in 10,368 patients undergoing atrial fibrillation ablation from 2000 to 2015. Computed tomography scans were performed three to six months after the procedures. Severe pulmonary vein stenosis was observed in 52 patients, or 0.5%. The left superior pulmonary vein represented 51% of all severely stenosed veins.

Percutaneous interventions were performed in 43 patients, and complications occurred in five, including three pulmonary vein ruptures, one stroke and one phrenic injury. Over a median follow-up of 25 months, 41, or 79%, of patients remained arrhythmia-free.

In our next paper, Koichi Nagashima and associates compared hot balloon ablation and cryoballoon ablation in a 165 consecutive patients who underwent initial atrial fibrillation catheter ablation. Of the 165 patients, 74 propensity score-matched patients equally divided between hot balloon ablation and cryoballoon ablation were studied.

Patients' characteristics included age, sex, body mass index, atrial fibrillation subtype, CHA2DS2-VASc score, and left atrial dimension were similar between the two groups. 52% of the hot balloon ablation patients required touch-up with radiofrequency ablation for residual/dormant pulmonary vein condu...