Ezekowitz JA et al. (2007) Systematic review: implantable cardioverter defibrillators for adults with left ventricular systolic dysfunction. Ann Intern Med 147: 251–262

Patients with left ventricular systolic dysfunction are at risk of ventricular arrhythmias and sudden cardiac death. Meta-analyses of randomized controlled trials (RCTs) have demonstrated that, in these patients, implantable cardioverter-defibrillators (ICDs) reduce mortality by 26% and sudden cardiac death by 57%. Some cardiologists, however, question whether the benefits of ICDs seen in clinical trials extend to clinical practice, where physicians who perform implantation procedures might not have the same level of experience.

Ezekowitz et al. analyzed data from observational studies that examined the use and safety of ICDs in clinical practice and from more-recent clinical trials that assessed the risks and benefits of ICDs tested under ideal circumstances. Data were extracted from 12 RCTs that reported on mortality and ICD use and 76 observational studies that examined safety or efficacy.

Overall, in adult patients with left ventricular systolic dysfunction, ICDs reduced mortality by 20% in RCTs and by 46% in observational studies, countering the concern that ICDs might be less beneficial in clinical practice than in the trial setting. The authors recommend that future studies develop risk-stratification tools to aid the identification of those patients who are most and least likely to benefit from an ICD. It is particularly important, they note, that patients unsuitable for the procedure are not exposed unnecessarily to the risks associated with implantation.