Patients upgraded to cardiac resynchronization therapy due to pacing-induced cardiomyopathy are at low risk of life-threatening ventricular arrhythmias: a long-term cause-of-death analysis

Abstract

Aims: Upgrade to cardiac resynchronization therapy (CRT) should be offered to patients who have developed pacing-induced cardiomyopathy with conventional right ventricular pacing. The extent to which those patients would also benefit from defibrillator back-up at the time of CRT upgrade is, however, unknown. Methods:Retrospective observational cohort study of 199 patients with pacing-induced cardiomyopathy (without history of sustained ventricular arrhythmia), including 104 upgraded to CRT-Pacemaker (CRT-P) and 95 upgraded to CRT-Defibrillator (CRT-D). The incidence of ventricular arrhythmias and, through a cause-of-death analysis based on clinical data and necropsy results, the risk of sudden arrhythmic death were assessed and compared between the two groups.Results: During a mean follow-up of 66±24 months, 40 (38.5%) CRT-P patients died: three from primary arrhythmic death, while the remaining died of different causes (especially progressive heart failure), giving an incidence of 6.2 sudden arrhythmic deaths per 1000 patient-years. No episode of sustained VT was observed in the study group. There were no sudden arrhythmic deaths in the CRT-D group during a shorter follow-up, but the small and non-significant difference in all-cause mortality between CRT-P and CRT-D groups was mostly accounted for by an increase in non-sudden death. Women upgraded to CRT were at particularly low risk of all-cause mortality compared with men (HR 0.232, p=0.048). Conclusion:Our findings suggest that patients who develop pacing-induced cardiomyopathy and are upgraded to CRT may not derive any significant benefit from the addition of the defibrillator in the absence of a history of ventricular arrhythmias. 3 KEYWORDSCardiac resynchronization therapy; pacemaker; implantable cardioverter-defibrillator; ventricular arrhythmias; cause-of-death; sudden arrhythmic death. 4 CONDENSED ABSTRACTIn our retrospective cohort study of 199 patients with pacing induced cardiomyopathy submitted to CRT upgrade, we have found that the risk of sustained ventricular tachycardia or sudden arrhythmic death is very low, and any increased mortality risk in those receiving CRT-P compared with CRT-D is mostly accounted for by an increase in non-sudden death. 5 WHAT'S NEW? Our study provides the largest and longest-term cause-of-death analysis in patients with pacing-induced cardiomyopathy based on post-mortem examinations and death certificates. We have found that the annual risk of sudden arrhythmic death or sustained ventricular arrhythmias in these patients is very low, and similar to a control group implanted with CRT with a defibrillator.  The small difference in all-cause mortality between CRT-Pacemaker and CRTDefibrillator in patients with pacing-induced cardiomyopathy is mostly accounted for by an increase in non-sudden death. Our results suggest that an upgrade to CRT-Defibrillator in patients with pacinginduced cardiomyopathy may convey no additional benefit when compared with upgrade to CRT-Pacemaker, and the cost-effectiveness ratio of...

Clinical outcomes after upgrading from pacemakers to cardiac resynchronization therapy

“…Over a mean follow‐up of 5.5 years, three of 104 (2.9%) patients in the CRT‐P arm had a primary arrhythmic death (6.2 sudden arrhythmic deaths per 1,000 patient‐years). The authors concluded that patients with pacing‐induced cardiomyopathy and no prior ventricular arrhythmias who are upgraded to CRT may not derive any significant benefit from the addition of a defibrillator . In contrast, we found that CRT‐D upgrade was consistently superior to CRT‐P upgrades with respect to the three main endpoints, even after inverse probability weighting.…”

Survival of patients with pacing‐induced cardiomyopathy upgraded to CRT does not depend on defibrillation therapy

“…The narrowing of QRS complexes, as well as the resolution of electromechanical dyssynchrony, for example, apical rocking and septal flash in echocardiography after CRT, is a well‐described predictor of reverse LV remodeling, LVEF improvement, and a reduction in the number of ventricular arrhythmia episodes and mortality 11,16,21,24 . Correction of severe dyssynchrony seems to be crucial in the PICM population in the absence of a history of ventricular arrhythmias influencing survival despite the use of HV therapy 2,7,8,9 . Our findings, by directly comparing the PM/CRT‐P versus the PM/CRT‐D group, seems to confirm these observations in the patients at high risk of PICM, without severe, irreversible LV dysfunction.…”

“…The current European Society of Cardiology guidelines give II B recommendations for an upgrade from right ventricular to biventricular (BiV) pacing in patients who develop worsening Heart Failure (HF) due to a high percentage of RVP, despite Optimal Medical Therapy (OMT) 6 . However, there are only a few data on whether the addition of implantable cardioverter defibrillator (ICD) to CRT in the PICM population affects survival 7,8,9 …”

Effect of right ventricular pacing on left ventricular systolic function in patients with Tetralogy of Fallot

“…The prevalence of PICM ranges from 12% to 20%, and the risk factors for PICM include frequent RV pacing, QRS duration, preexisting left bundle branch block, and LV systolic dysfunction prior to pacemaker implantation [1], [2], [4], [5]. Biventricular pacing is effective for preventing and reversing PICM, and is endorsed by the practice guidelines for selected cases [1], [2], [3], [4], [6].…”