Feasibility and efficacy of electrical cardioversion after cardiac resynchronization implantation in patients with permanent atrial fibrillation

Atrial fibrillation in cardiac resynchronization therapy

Patients with atrial fibrillation (AF) were largely excluded from the major clinical trials of cardiac resynchronization therapy (CRT), despite the presence of AF in up to 40% of patients receiving CRT in clinical practice. AF appears to attenuate the response to CRT, by the combination of a reduction in biventricular pacing and the loss of atrioventricular synchrony. In addition, remodeling secondary to CRT may influence the progression of AF. Management options for patients with AF and CRT include rate control, with drugs or atrioventricular node ablation, or rhythm control, with electrical cardioversion and antiarrhythmic therapy, or AF catheter ablation. The evidence for these therapies in patients with CRT is largely limited to observational studies or inferred from randomized studies in the general heart failure population. In this review, we explore the complex interaction between AF, heart failure, and CRT and discuss the evidence for the treatment options in this difficult patient cohort.

Cardiac resynchronization therapy defibrillators in patients with permanent atrial fibrillation

Aims

There are conflicting data on the benefit of cardiac resynchronization therapy (CRT) in heart failure (HF) patients with permanent atrial fibrillation (AF). We aimed to compare patient outcomes according to the presence or absence of permanent AF at device implantation.

Methods and results

We retrospectively analysed remote monitoring data from 1141 CRT defibrillators. Propensity score with inverse‐probability weighting method was used to balance AF and sinus rhythm (SR) groups. Analysis endpoints included total mortality, appropriate defibrillation shocks, and CRT percentage. There were 229 patients (20.1%) in the AF group and 912 patients (79.9%) in the SR group. Compared with SR patients, AF patients were older (median age, 77 vs. 72 years, P < 0.001), more frequently male (82.5% vs. 75.5%, P = 0.02), and had higher heart rate (75.7 vs. 71.0 b.p.m., P < 0.001). Of the 229 AF patients, 162 (70.7%) received suboptimal CRT (<98%) and 67 (29.3%) had adequate CRT (≥98%). During a median follow‐up of 24 months, total mortality did not differ between AF and SR groups (propensity‐score‐weighted hazard ratio, HR 1.32 [95% confidence interval, 0.82–2.15], P = 0.25). The risk of appropriate shocks was significantly higher in the AF group with <98% CRT than in the SR group (weighted‐HR, 1.99 [1.21–3.26], P = 0.006) and was similar in the AF group with ≥98% CRT versus the SR group (1.29 [0.66–2.53], P = 0.45). During follow‐up, sinus rhythm was recovered in 23 patients in the AF group (10%) after a median time of 106 (42–256) days. The rate of sinus rhythm recovery in the AF group was 4.5 (95% CI, 2.8–6.7) per 100 patient‐years; the rate of permanent AF occurrence in the SR group was 2.5 (95% CI, 1.9–3.3) per 100 patient‐years.

Conclusions

Although mortality was similar across patient groups, patients with permanent AF and suboptimal CRT had twofold higher risk of appropriate shocks than SR patients or AF patients with CRT ≥ 98%.

Nonpharmacological Treatment of Atrial Fibrillation: What Is the Role of Device Therapy?

Atrial fibrillation is the most common arrhythmia in the adult population, and its incidence and prevalence are still rising. Cardiac devices are widely used in clinical practice in the management of various rhythm disturbances and heart failure treatment. Many patients who receive a pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy also experience atrial fibrillation in the course of their life. Therefore, this review aims to describe the role of these devices in the treatment and prevention of atrial fibrillation in the device recipients. In addition, all these implantable devices also serve as permanent ECG (electrocardiogram) monitors, thus providing important information about the presence and characteristics of atrial fibrillation that may or may not be detected by the patient but can modify our therapeutical approach with regard to the stroke prevention.

Internal Versus External Electrical Cardioversion of Atrial Arrhythmia in Patients With Implantable Cardioverter-Defibrillator: A Randomized Clinical Trial

BACKGROUND

Atrial arrhythmias are common in patients with implantable cardioverter-defibrillator (ICD). External shocks and internal cardioversion through commanded ICD shock for electrical cardioversion are used for rhythm-control. However, there is a paucity of data on efficacy of external versus internal cardioversion and on the risk of lead and device malfunction. We hypothesized that external cardioversion is noninferior to internal cardioversion for safety, and superior for successful restoration of sinus rhythm.

METHODS

Consecutive patients with ICD undergoing elective cardioversion for atrial arrhythmias at 13 centers were randomized in 1:1 fashion to either internal or external cardioversion. The primary safety end point was a composite of surrogate events of lead or device malfunction. Conversion of atrial arrhythmia to sinus rhythm was the primary efficacy end point. Myocardial damage was studied by measuring troponin release in both groups.

RESULTS

N=230 patients were randomized. Shock efficacy was 93% in the external cardioversion group and 65% in the internal cardioversion group (P<0.001). Clinically relevant adverse events caused by external or internal cardioversion were not observed. Three cases of pre-existing silent lead malfunction were unmasked by internal shock, resulting in lead failure. Troponin release did not differ between groups.

CONCLUSIONS

This is the first randomized trial on external vs internal cardioversion in patients with ICDs. External cardioversion was superior for the restoration of sinus rhythm. The unmasking of silent lead malfunction in the internal cardioversion group suggests that an internal shock attempt may be reasonable in selected ICD patients presenting for electrical cardioversion.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT03247738.

Electrical cardioversion of patients with implanted pacemaker or cardioverter-defibrillator: results of a survey of german centers and systematic review of the literature

AIMS

A relevant number of patients presenting for electrical cardioversion carry a pacemaker (PM) or ICD. Case reports suggest a potential hazard of external cardioversion/defibrillation. The incidence of shock related device complications is unknown. No guidelines or recommendations by international medical societies for a cardioversion protocol of cardiovascular implantable electronic device (CIED) patients exist. We conducted a nationwide survey to gather real-world clinical data on the current clinical approach towards these patients during electrical cardioversion and to estimate the incidence of shock-related complications.

METHODS AND RESULTS

Ninety hospitals with > 380 ECV in 2014 were identified from mandatory hospital quality reports and 60 were randomly selected. All centers were provided with a standardized questionnaire on the general proceedings and complications during electrical cardioversion of pacemaker, ICD and CRT patients (CIED patients). Thirty-two centers (53%) participated in the survey. In total, 16,554 ECV were reported (534 ± 314 per center). Biphasic cardioversion with a first shock energy of ≥ 150 J via adhesive patches in antero-posterior orientation was preferred by most centers (78%). Eleven percent (n = 1809) of pts were reported to carry a PM/ICD. The ECV protocol was heterogeneous among centers. Complications associated with electrical cardioversion were reported in 11/1809 patients (0.6%), all were transitory elevations of pacing thresholds.

CONCLUSIONS

In this nationwide snapshot survey of cardioversion procedures in Germany, approximately 11% of patients presenting for elective electrical cardioversion were pacemaker or ICD carriers. Cardioversion protocols in these patients are heterogeneous throughout centers and mostly not in accordance with recommendation of the German Cardiac Society. Complications associated with external electrical cardioversion are rare. Controlled trials and large registries are necessary to provide evidence for future recommendations.

Cardiac Resynchronization in Patients with Atrial Fibrillation

Atrial fibrillation (AF) occurs in one of four patients undergoing cardiac resynchronization therapy (CRT).-Without special therapy, the prognosis of AF patients with CRT has been generally worse than those in sinus rhythm. The importance of a high percentage of biventricular pacing (BIV%) was confirmed in a large study where the mortality was inversely associated with BIV% both in the presence of normal sinus and atrial paced rhythm and with AF. The greatest reduction in mortality was observed with BIV% >98%. Patients with BIV% >99.6% experienced a 24% reduction in mortality (p < 0.001) while those with BIV% <94.8% had a 19% increase in mortality. The optimal BIV% cut-point was 98.7%. This cutoff would appear mandatory but it would be best to approach 100%. Careful evaluation of device interrogation data upon which the BiV% is based is essential because the memorized data can vastly overestimate the percentage of truly resynchronized beats since it does not account for fusion and pseudofusion between intrinsic (not paced) and paced beats. The recently published randomized CERTIFY trial provides unequivocal proof of the value of AV junctional (AVJ) ablation in CRT patients with AF. This trial confirmed the favorable results of AVJ ablation by many other studies and two important meta-analyses and therefore established the firm recommendation that the procedure should be performed in most, if not all, patients with permanent AF as well as those with frequent and prolonged episodes of paroxysmal AF. Patients after AVJ have improved mortality with a mortality similar to those in sinus rhythm. The AVJ ablation procedure carries the theoretical risk of device failure and death in pacemaker dependent patients. An inappropriate first ICD shock for AF seems to increase mortality. Increased long-term mortality after an inappropriate shock may be due to the underlying atrial arrhythmia substrate as opposed to the effect of the shock itself.

Comparison of the rhythm control treatment strategy versus the rate control strategy in patients with permanent or long-standing persistent atrial fibrillation and heart failure treated with cardiac resynchronization therapy - a pilot study of Cardiac Resynchronization in Atrial Fibrillation Trial (Pilot-CRAfT): study protocol for a randomized controlled trial

BACKGROUND

The only subgroups of patients with heart failure and atrial fibrillation in which the efficacy of cardiac resynchronization therapy has been scientifically proven are patients with indications for right ventricular pacing and patients after atrioventricular junction ablation. However it is unlikely that atrioventricular junction ablation would be a standard procedure in the majority of the heart failure patients with cardiac resynchronization therapy and concomitant atrial fibrillation due to the irreversible character of the procedure and a spontaneous sinus rhythm resumption that occurs in about 10% of these patients.

METHODS/DESIGN

Pilot-CRAfT is the first randomized controlled trial evaluating the efficacy of a rhythm control strategy in atrial fibrillation patients with cardiac resynchronization therapy devices. The aim of this prospective, single center randomized controlled pilot study is to answer the question whether the patients with cardiac resynchronization therapy and permanent atrial fibrillation would benefit from a strategy to restore and maintain sinus rhythm (that is 'rhythm control' strategy) in comparison to rate control strategy. The study population consists of 60 patients with heart failure and concomitant long-standing persistent or permanent atrial fibrillation who underwent a cardiac resynchronization therapy device implantation at least 3 months before qualification. Study participants are randomly assigned to the rhythm control strategy (including electrical cardioversion and pharmacotherapy) or to the rate control group whose goal is to control ventricular rate. The follow-up time is 12 months. The primary endpoint is the ratio of effectively captured biventricular beats. The secondary endpoints include peak oxygen consumption, six-minute walk test distance, heart failure symptom escalation, reverse remodelling of the heart on echo and quality of life.

TRIAL REGISTRATION

NCT01850277 registered on 22 April 2013 (ClinicalTrials.gov).

Low efficacy of cardioversion of persistent atrial fibrillation with the implantable cardioverter-defibrillator

AIMS

Atrial fibrillation (AF) and heart failure are conditions that often coexist. Consequently, many patients with an implantable cardioverter-defibrillator (ICD) present with AF. We evaluated the effectiveness of internal cardioversion of AF in patients with an ICD.

METHODS

Retrospectively, we included 27 consecutive ICD patients with persistent AF who underwent internal cardioversion using the ICD. When ICD cardioversion failed, external cardioversion was performed.

RESULTS

Patients were predominantly male (89 %) with a mean (SD) age of 65 ± 9 years and left ventricular ejection fraction of 36 ± 17 %. Only nine (33 %) patients had successful internal cardioversion after one, two or three shocks. The remaining 18 patients underwent external cardioversion after they failed internal cardioversion, which resulted in sinus rhythm in all. A smaller left atrial volume (99 ± 36 ml vs. 146 ± 44 ml; p = 0.019), a longer right atrial cycle length (227 (186-255) vs. 169 (152-183) ms, p = 0.030), a shorter total AF history (2 (0-17) months vs. 40 (5-75) months, p = 0.025) and dual-coil ICD shock (75 % vs. 26 %, p = 0.093) were associated with successful ICD cardioversion.

CONCLUSION

Internal cardioversion of AF in ICD patients has a low success rate but may be attempted in those with small atria, a long right atrial fibrillatory cycle length and a short total AF history, especially when a dual-coil ICD is present. Otherwise, it seems reasonable to prefer external over internal cardioversion when it comes to termination of persistent AF.