Circulation: Arrhythmia and Electrophysiology September 2018 Issue

09/18/18 • 11 min

Circulation: Arrhythmia and Electrophysiology On the Beat

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....

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Circulation: Arrhythmia and Electrophysiology August 2018 Issue

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...

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Circulation: Arrhythmia and Electrophysiology October 2018 Issue

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, Ruairidh Martin and associates used ultra-high-density mapping to access the ventricular tachycardia circuit dependent upon re-entry, with scar regions in 36 tachycardias in 31 patients. The author has found that 11 of the ventricular tachycardia circuits and isthmuses were single-loop, and 25 were double-loop. Three had two entrances, five had two exits, and fifteen had dead-end activation. Isthmuses were defined by barriers which included anatomical obstacles, lines of block, and slow conduction in 27 out of 36 isthmuses. The barrier to conduction in isthmus appeared to be partially functional in 75% of circuits. Isthmus voltage is often higher in ventricular tachycardia than in sinus or paced rhythms. The authors found that conduction velocity in the VT isthmus slowed at the isthmus entrances and exits when compared with mid-isthmus. The mean conduction velocity was 0.08 meters per second in entrance zones, 0.29 meters per second in isthmus regions, p < 0.0001, and 0.11 meters per second in exit regions. P = 0.002.

In our next paper Daniel Duprez and associates found that plasma collagen biomarkers, particularly at elevated levels, were associated with excess risk of atrial fibrillation. In a stratified sample of the Multi-Ethnic Study of Atherosclerosis (MESA), initially age 45 to 84 years, the authors examined in 3,071 participants plasma Procollagen Type III N-Terminal Propeptide, also known as P3NP, which reflects collagen synthesis in degradation in Collagen Type I Carboxy-Terminal Telopeptide, also known as ICTP, which reflects collagen degradation at baseline. The authors aimed to determine if the levels of these biomarkers were associated with incident atrial fibrillation in participants initially free of overt cardiovascular disease. Incident atrial fibrillation in ten-year follow-up was based on a hospital ICD code for atrial fibrillation or atrial flutter, in or outpatient Medicare claims, or ECG ten years after baseline. The authors found that baseline levels of these markers were positively related, both p < 0.0001 to incident atrial fibrillation in a model adjusting for age, race, ethnicity, and sex. These findings were attenuated but remain statistically significant after further adjustment for systolic blood pressure, height, body mass index, smoking, and renal function.

In our next paper, Ahmet Adiyaman and associates conducted a randomized controlled trial comparing the safety and efficacy of minimally invasive thoracoscopic pulmonary vein isolation with left atrial appendage ligation versus percutaneous catheter ablation pulmonary vein isolation. In 52 patients with symptomatic paroxysmal or early persistent atrial fibrillation, paroxysmal atrial fibrillation was present in 74% of patients. The authors found that percutaneous pulmonary vein isolation with a 56% single procedure arrhythmia-free survival at two years was not inferior to minimally invasive thoracoscopic pulmonary vein isolation with left atrial appendage ligation, which had a 29% arrhythmia freedom, p = 0.059. Procedure-related major adverse events occurred in 21% of patients undergoing minimally invasive thoracoscopic pulmonary vein isolation, compared to none undergoing percutaneous catheter ablation with p = 0.029.

In the next paper, Richard Ang and associates examined whether the glucagon-like peptide-1 receptor agonist exendin 4 has an effect on ventricular action potential duration in susceptibility to ventricular arrhythmia in the rat heart in vivo and ex vivo. Ventricular monophasic action potentials recorded in anesthetized rats in vivo in isolated profused rat hearts in sinus rhythm and/or ventricular pacing. In vivo systemic administration of exendin 4 increased heart rate and this effect was abolished by beta adrenoceptor blockade. Despite causing sympathetic activation, exendin 4 increased axon potential duration at 90% repolarization, APD90, during ventricular pacing by 7% and reversed the effect of beta adrenoceptor agonist Dobutamine on APD90. In isolated profused hearts, 3 nanomolar exendin 4 increased APD90 by 14% with no effect on heart rate. Exendin 4 also reduced ventricular arrhythmia inducibility in conditions of beta adrenoceptor stimulation with Isoproterenol. Exendin 4 effects on action potential duration in ventricular arrhythmia susceptibility were prevented in conditions of muscarinic receptor blockade or inhibition of nitric oxide synthase. The authors concluded that glucagon-like peptide-1 receptor activation effectively reverses the effects of beta adrenoceptor stimulation on cardiac ventricular excitability and reduces ventricular arrhythmic potential. The effect of glucagon-like peptide-1 receptor activation on the ventricular...