Neuromodulation for the Treatment of Refractory Ventricular Arrhythmias

BACKGROUND

Neuromodulation is increasingly recognized as a therapeutic strategy for patients with refractory ventricular arrhythmias (VAs). Percutaneous stellate ganglion blockade (SGB), transcutaneous magnetic stimulation (TcMS), and surgical cardiac sympathetic denervation (CSD) have all been utilized in this setting.

OBJECTIVES

This study sought to characterize contemporary use and outcomes of these neuromodulation techniques for patients with refractory VA.

METHODS

This retrospective cohort study included all patients at the Hospital of the University of Pennsylvania with antiarrhythmic drug (AAD)-refractory VA from 2019 to 2021 who were treated with SGB, TcMS, or CSD.

RESULTS

A total of 34 patients (age 61 ± 14 years, 15 polymorphic VAs [44%], refractory to 1.8 ± 0.8 AADs) met inclusion criteria. SGB was performed on 11 patients (32%), TcMS on 19 (56%), and CSD on 7 (21%). Neuromodulation was associated with a reduction in the number of episodes of sustained VAs from 7 [IQR: 4-12] episodes in the 24 hours before the initial neuromodulation strategy to 0 [IQR: 0-1] episodes in the subsequent 24 hours (P < 0.001). During 1.2 ± 1.1 years of follow-up, 21 (62%) experienced recurrent VAs, and among those patients, the median time to recurrence was 3 [IQR: 1-25] days. Outcomes were similar among patients with monomorphic and polymorphic VAs. Among patients who had an acute myocardial infarction within 30 days before neuromodulation, the burden of VAs decreased from 11 [IQR: 7-12] episodes to 0 episodes in the 24 hours after treatment.

CONCLUSIONS

Autonomic neuromodulation with SGB, TcMS, or CSD in patients with AAD-refractory VAs is safe and results in substantial acute reduction of VA although recurrent arrhythmias are common, and not all patients experience a reduction in arrhythmia burden.

Safety and efficacy of catheter ablation for ventricular tachycardia in elderly patients with structural heart disease: a systematic review and meta-analysis

PURPOSE

Data regarding the age-specific outcomes of VT ablation in patients with structural heart disease (SHD) are scarce. We performed a systematic review and meta-analysis to evaluate the outcomes of VT ablation in elderly vs. younger patients with SHD.

METHODS

MEDLINE/PubMed, Cochrane, and Google Scholar and references comparing VT ablation in elderly vs. younger patients were screened and studies included if matching inclusion and exclusion criteria.

RESULTS

Five retrospective studies enrolling 2778 SHD patients (868 elderly vs. 1910 younger) were included. Compared to younger subjects, the elderly showed similar results in terms of acute ablation success (OR 0.78, 95% CI 0.54-1.13, p = 0.189) and minor complications (OR 1.74, 95% CI 0.74-4.09, p = 0.205), a trend toward a higher risk of major complications (OR 2.30, 95% CI 0.83-6.40, p = 0.110) and significantly higher rates of all complications (OR 2.67, 95% CI 1.51-4.71, p = 0.001) and periprocedural mortality (OR 1.93, 95% CI 1.24-3.01, p = 0.004). At a mean follow-up of 18 months, elderly patients showed similar long-term VT recurrence rate (OR 1.02, 95% CI 0.85-1.22, p = 0.861) and higher all-cause mortality (OR 2.00, 95% CI 1.40-2.86, p < 0.001). In elderly patients, urgent VT ablation is associated with higher risk of major complications (beta = 0.06, p < 0.001) and periprocedural mortality (beta = 0.03, p = 0.029), while advanced age is associated with higher risk of major complications (beta = 0.29 with p = 0.009) and all complications + periprocedural mortality (beta = 0.17 with p = 0.037).

CONCLUSIONS

Compared to younger patients, VT ablation in elderly showed similar results in terms of acute ablation success and long-term VT recurrence rate with a significantly higher risk of all complications, periprocedural mortality, and long-term mortality, especially when the procedure is performed urgently and in the most aged patients. Large prospective multicenter randomized trials are required to confirm these findings.

Safety of Pill-in-the-Pocket Class 1C Antiarrhythmic Drugs for Atrial Fibrillation

BACKGROUND

Guidelines recommend that initial trial of a "pill-in-the-pocket" (PIP) Class 1C antiarrhythmic drug (AAD) for cardioversion of atrial fibrillation (AF) be performed in a monitored setting because of the potential for adverse reactions.

OBJECTIVES

This study sought to characterize real-world, contemporary use of the PIP approach, including the setting of initiation and incidence of adverse events.

METHODS

This retrospective cohort study included all patients at the Hospital of the University of Pennsylvania treated with a PIP approach for AF between 2007 and 2020.

RESULTS

A total of 273 patients (age 56 ± 13 years; 182 [67%] male; CHA₂DS₂VASc score 1.1 ± 1.2) took a first dose of PIP AAD. Flecainide was used in 151 (55%) and propafenone in 122 (45%). The first dose of PIP AAD was taken in a monitored setting in 167 (62%). Significant adverse events occurred in 7 patients (3%), 2 of whom had taken the dose in a monitored setting. Significant adverse events included unexplained syncope (1 of 7), symptomatic bradycardia/hypotension (4 of 7), and 1:1 atrial flutter (2 of 7). All occurred in patients taking 300 mg of flecainide (n = 4) or 600 mg of propafenone (n = 3). Electrical cardioversion was performed in 29 (11%) patients because of failure of the AAD to terminate AF. One patient required intravenous fluids and vasopressors for 2 hours because of persistent hypotension and bradycardia. Two patients required permanent pacemakers for bradycardia. The remaining patients required no intervention.

CONCLUSIONS

Our data support the current recommendation to initiate PIP AAD in a monitored setting because of rare significant adverse reactions that can require urgent intervention.

Impact of Left Ventricular Papillary Muscle Ventricular Arrhythmia Ablation on Mitral Valve Function

BACKGROUND

Although efficacious, catheter ablation (CA) of ventricular arrhythmias (VAs) originating from left ventricular (LV) papillary muscles (PAPs) has the potential to affect mitral valve (MV) function.

OBJECTIVES

The aim of this study was to determine whether lesions delivered during CA of VAs from LV PAPs affected MV function.

METHODS

Consecutive patients undergoing CA of LV PAP VAs from January 2015 to December 2020 in whom both preprocedural and postprocedural transthoracic echocardiography was performed were included. Radiofrequency ablation was performed with an irrigated-tip catheter with or without contact force sensing and intracardiac echocardiographic guidance. The PAPs were delineated into segments: tip, body, and base. Pre- and post-CA transthoracic echocardiograms were reviewed to assess MV regurgitation, which was graded 0 (none), 1 (mild), 2 (moderate), or 3 (severe). A change of ≥2 grades from baseline was considered significant.

RESULTS

A total of 103 patients (mean age 63 ± 15 years, 78% men) were included. VAs were ablated from the anterolateral PAP in 35% (n = 36), posteromedial PAP in 55% (n = 57), and both PAPs in 10% (n = 10). Lesion distribution was as follows: PAP tip in 52 (50%), PAP base in 34 (33%), PAP body in 13 (13%), and entire PAP in 4 (4%). The mean number of lesions delivered was 16 ± 13 (median 14). Of 103 patients, 102 (99%) showed no change in MV function.

CONCLUSIONS

Using intracardiac echocardiographic guidance, lesions can be safely delivered on various aspects of this structure without adverse impact on MV function.

Advances in Cardiac Electrophysiology

Despite the global COVID-19 pandemic, during the past 2 years, there have been numerous advances in our understanding of arrhythmia mechanisms and diagnosis and in new therapies. We increased our understanding of risk factors and mechanisms of atrial arrhythmias, the prediction of atrial arrhythmias, response to treatment, and outcomes using machine learning and artificial intelligence. There have been new technologies and techniques for atrial fibrillation ablation, including pulsed field ablation. There have been new randomized trials in atrial fibrillation ablation, giving insight about rhythm control, and long-term outcomes. There have been advances in our understanding of treatment of inherited disorders such as catecholaminergic polymorphic ventricular tachycardia. We have gained new insights into the recurrence of ventricular arrhythmias in the setting of various conditions such as myocarditis and inherited cardiomyopathic disorders. Novel computational approaches may help predict occurrence of ventricular arrhythmias and localize arrhythmias to guide ablation. There are further advances in our understanding of noninvasive radiotherapy. We have increased our understanding of the role of His bundle pacing and left bundle branch area pacing to maintain synchronous ventricular activation. There have also been significant advances in the defibrillators, cardiac resynchronization therapy, remote monitoring, and infection prevention. There have been advances in our understanding of the pathways and mechanisms involved in atrial and ventricular arrhythmogenesis.

Extra-cardiac BCAA catabolism lowers blood pressure and protects from heart failure

Pharmacologic activation of branched-chain amino acid (BCAA) catabolism is protective in models of heart failure (HF). How protection occurs remains unclear, although a causative block in cardiac BCAA oxidation is widely assumed. Here, we use in vivo isotope infusions to show that cardiac BCAA oxidation in fact increases, rather than decreases, in HF. Moreover, cardiac-specific activation of BCAA oxidation does not protect from HF even though systemic activation does. Lowering plasma and cardiac BCAAs also fails to confer significant protection, suggesting alternative mechanisms of protection. Surprisingly, activation of BCAA catabolism lowers blood pressure (BP), a known cardioprotective mechanism. BP lowering occurred independently of nitric oxide and reflected vascular resistance to adrenergic constriction. Mendelian randomization studies revealed that elevated plasma BCAAs portend higher BP in humans. Together, these data indicate that BCAA oxidation lowers vascular resistance, perhaps in part explaining cardioprotection in HF that is not mediated directly in cardiomyocytes.

Catheter Ablation for Atrial Fibrillation in Adult Congenital Heart Disease: An International Multicenter Registry Study

BACKGROUND

Data on atrial fibrillation (AF) ablation and outcomes are limited in patients with congenital heart disease (CHD). We aimed to investigate the characteristics of patients with CHD presenting for AF ablation and their outcomes.

METHODS

A multicenter, retrospective analysis was performed of patients with CHD undergoing AF ablation between 2004 and 2020 at 13 participating centers. The severity of CHD was classified using 2014 PACES/HRS guidelines. Clinical data were collected. One-year complete procedural success was defined as freedom from atrial tachycardia or AF in the absence of antiarrhythmic drugs or including previously failed antiarrhythmic drugs (partial success).

RESULTS

Of 240 patients, 127 (53.4%) had persistent AF, 62.5% were male, and mean age was 55.2±0.9 years. CHD complexity categories included 147 (61.3%) simple, 69 (28.8%) intermediate, and 25 (10.4%) severe. The most common CHD type was atrial septal defect (n=78). More complex CHD conditions included transposition of the great arteries (n=14), anomalous pulmonary veins (n=13), tetralogy of Fallot (n=8), cor triatriatum (n=7), single ventricle physiology (n=2), among others. The majority (71.3%) of patients had trialed at least one antiarrhythmic drug. Forty-six patients (22.1%) had reduced systemic ventricular ejection fraction <50%, and mean left atrial diameter was 44.1±0.7 mm. Pulmonary vein isolation was performed in 227 patients (94.6%); additional ablation included left atrial linear ablations (25.4%), complex fractionated atrial electrogram (19.2%), and cavotricuspid isthmus ablation (40.8%). One-year complete and partial success rates were 45.0% and 20.5%, respectively, with no significant difference in the rate of complete success between complexity groups. Overall, 38 patients (15.8%) required more than one ablation procedure. There were 3 (1.3%) major and 13 (5.4%) minor procedural complications.

CONCLUSIONS

AF ablation in CHD was safe and resulted in AF control in a majority of patients, regardless of complexity. Future work should address the most appropriate ablation targets in this challenging population.

Impact of atrial fibrillation recurrences during the blanking period following catheter ablation on long-term arrhythmia-free survival: a prospective study with continuous monitoring

BACKGROUND

The significance of atrial fibrillation (AF) recurrences during the 90-day blanking period following catheter ablation is controversial. Studies to date examining the impact of AF recurrences during the blanking period have been limited by intermittent monitoring. We sought to test whether AF recurrences during the blanking period are associated with long-term recurrences using continuous monitoring.

METHODS

Patients undergoing AF ablation by a single operator at an academic medical center between 2015 and 2019, who either already had a cardiac implantable electronic device (CIED) with an atrial lead or received an insertable cardiac monitor (ICM), were followed for long-term AF recurrence. Recurrence was defined as > 30 s by CIED and > 2 min by ICM. All device-reported AF episodes were adjudicated by a physician.

RESULTS

Of 196 consecutive patients, 51 (26%) had AF recurrence in the blanking period and 145 (74%) did not. Over the year following ablation, those who had an AF recurrence in the blanking period were significantly more likely to have long-term AF recurrences than those without AF in the blanking period (log rank p < 0.001). The higher the burden of AF recurrences during the blanking period, the more likely AF was to recur long-term (hazard ratio 1.04 [CI 1.01-1.06] per 1% increase in burden, p = 0.002).

CONCLUSION

Using continuous monitoring of a sizable population, we confirmed that AF recurrences in the blanking period following ablation are in fact associated with long-term AF recurrences. The higher the burden of recurrence, the more likely AF is to recur long-term.

Subcutaneous Implantable Cardioverter-defibrillator Explantation-A Single Tertiary Center Experience

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an appealing alternative to transvenous ICD systems. However, data on indications for S-ICD explantations are sparse. The objective of this study was to assess the incidence and indications for S-ICD explantation at a large tertiary referral center. We conducted a retrospective study of all S-ICD explantations performed from 2014–2020. Data on demographics, comorbidities, implantation characteristics, and indications for explantation were collected. A total of 64 patients underwent S-ICD explantation during the study period. During that time, there were 410 S-ICD implantations at our institution, of which 53 (12.9%) were explanted with a mean duration from implant to explant of 19.7 ± 20.1 months. The mean age of the patients at explantation was 44.8 ± 15.3 years, and 42% (n = 27) were women. The indication for S-ICD implantation was primary prevention in 58% and secondary prevention in 42% of patients, respectively. The most common reason for explantation was infection (32.8%), followed by abnormal sensing (25%) and the need for pacing (18.8%). Those who underwent S-ICD explantation for pacing indications were significantly older (55.7 ± 13.6 vs. 42.3 ± 14.6 years, P = 0.005) with a wider QRS duration (111 ± 19 vs. 98 ± 19 ms, P = 0.03) at device implantation compared to patients who underwent explantation for other indications. The incidence of S-ICD explantation in a large tertiary practice was 12.9%. While infection was the indication for one-third of the explantations, a significant number of explantations were due to sensing abnormalities and the need for pacing. These data may have implications for patient selection for S-ICD implantation.

Utility of Prolonged Duration Endocardial Ablation for Ventricular Arrhythmias Originating From the Left Ventricular Summit

OBJECTIVES

This study sought to explore whether prolonged duration (PD) radiofrequency ablation (RFA) from adjacent endocardial locations can improve catheter ablation (CA) outcomes of left ventricular summit (LVS) ventricular arrhythmias (Vas).

BACKGROUND

CA of VAs originating from the LVS region can be challenging.

METHODS

Patients undergoing CA of LVS VAs from January 1, 2015, to December 31, 2019, were included. Standard RFA approach involved incremental power titration (20-45 W) over 60-120 seconds with irrigated tip catheter to achieve 10%-12% impedance drop. Prolonged duration RFA involved similar power titration; however, lesion application was extended beyond 120 seconds (maximum 5 minutes). Lesions were confined to lowest aspect of aortic cusps and/or subvalvular LV outflow tract region (≤0.5 cm from the valve). Procedural success was defined as suppression of VA ≥30 minutes postablation and clinical success as no arrhythmia symptoms on follow-up and >80% reduction of VA burden on postprocedure monitor.

RESULTS

This study included 102 patients (60±14 years old, 62% male): standard RFA in 80 and PD RFA in 38. Procedural success was achieved in 54 patients with standard and 32 patients with PD RFA (68% vs 84%; P = 0.05). Short-term clinical success was achieved in 48 patients (60%) with standard and 30 patients (79%) with PD RFA (P = 0.04). Two pericardial effusions occurred (1 in each group) and no steam pops were noted. Patients in whom standard RFA was successful were more likely to have R/S ratio >1 or absence of qS in lead I (odds ratio: 3.35; 95% CI: 1.20-9.35; P = 0.03).

CONCLUSIONS

Prolonged duration RFA from adjacent endocardial locations is a safe and effective technique for successfully targeting challenging LVS VAs that fail standard RFA.