Cardiac resynchronization therapy effective for NYHA class 3 and 4 heart failure

Clinical Question

In addition to optimal pharmacotherapy, is cardiac resynchronization therapy incrementally safe and effective for adults with advanced heart failure due to left ventricular systolic dysfunction?

Bottom Line

Cardiac resynchronization therapy (CRT) with or without implantable cardioverter-defibrillator devices (ICDs) reduces overall morbidity and mortality in adults with advanced left ventricular systolic dysfunction (New York Heart Association [NYHA] class 3 or 4) and prolonged QRS duration. It remains uncertain whether there is any incremental benefit to combined CRT-ICD over CRT alone. (LOE = 1a)


McAlister FA, Ezekowitz J, Hooton N, et al. Cardiac resynchronization therapy for patients with left ventricular systolic dysfunction. A systematic review. JAMA 2007;297:2502-2514.  [PMID:17565085]

Study Design

Meta-analysis (other)




Various (meta-analysis)


These investigators thoroughly searched multiple databases including MEDLINE, the Cochrane Registry, EMBASE, Science Citation Index, abstracts of annual meetings, reference lists of pertinent articles, and data from device manufacturers for studies evaluating the safety and effectiveness of CRT with or without ICDs in adults with advanced left ventricular systolic dysfunction. Study selection and quality assessment occurred independently by multiple investigators. From an initial 7110 citations, the authors identified 14 randomized controlled trials (including 4420 patients) evaluating CRT effectiveness. In addition, findings from other studies, including prospective and retrospective observational studies were pooled to assess success rates and safety outcomes. In all trials, eligible patients had significant left ventricular dysfunction (mean ejection volume = 21% - 30%), prolonged QRS duration (155-209 ms), and symptomatic heart failure (91%, NYHA class 3 or 4; 9%, class 2). All patients received optimal pharmacotherapy. After pooling data from the RCTs, patients receiving CRT and pharmacotherapy compared with those receiving pharmacotherapy alone significantly improved symptomatically by at least 1 NYHA class (59% vs 37%, respectively; number needed to treat [NNT] = 5). Other significantly improved outcomes for patients receiving CRT included reduced hospitalization rates (19% vs 27%; NNT = 12) and reduced all-cause mortality (13.2% vs 15.5%; NNT = 43). No significant heterogeneity in results among the various trials was detected. Implant success rate for eligible patients was 93%, and 0.3% of patients died during the procedure. Overall, evidence was insufficient to demonstrate any significant benefit to CRT alone versus CRT plus ICD devices.