Are complications of implantable defibrillators under-estimated and benefits over-estimated?

Abstract

> It is ethically imperative that we are aware of the data, so that we can be honest with our patients . In a systematic review1 of 12 randomized controlled trials (RCTs) accounting for a total of 8516 patients with left ventricular (LV) systolic dysfunction (regardless of whether the patients had heart failure symptoms), 86% of whom had New York Heart Association (NYHA) class II or III symptoms, implantable cardioverter defibrillators (ICDs) reduced all-cause mortality by 20% (95% CI, 10–29); the reduction in total mortality was largely due to a 54% relative reduction of sudden death. In the same review, ICDs reduced all-cause mortality by 46% (95% CI, 32–57) in 11 observational cohort studies with contemporaneous control groups for a total of 9450 patients. In the observational studies, the mean left ventricular ejection fraction (LVEF) ranged from 0.19 to 0.46. The observational studies demonstrated a reduced frequency of non-cardiac death in ICD recipients (RR, 0.74). The fact that the controlled observational studies demonstrated a reduced frequency of non-cardiac death in ICD recipients suggests that clinicians select healthier patients for ICD insertion, and this probably accounts for the larger apparent benefit from ICDs on all-cause mortality in observational studies than in RCTs. This beneficial effect exists regardless of whether a patient has a history of haemodynamically apparent ventricular arrhythmias (primary or secondary prevention) or an ischaemic cause. However, in RCTs, LVEF ranged from 0.21 to 0.28 in the primary prevention trials and from 0.32 to 0.46 in the secondary prevention trials. While there was a definite survival benefit in patients with a history of ventricular tachyarrhythmias (HR = 0.77 [95% CI 0.65–0.91)] and in those in NYHA class II or III (HR = 0.81 [95% CI 0.69–0.95]), a post hoc meta-regression using aggregate trial data from 12 RCTs showed no significant … *Corresponding author. Tel: +39 0185 329 567, Fax: +39 0185 306 506, Email: mbrignole{at}ASL4.liguria.it