Cardiac resynchronization therapy in patients with left ventricular systolic dysfunction and right bundle branch block: a systematic review.

Background: Whether patients with right bundle branch block (RBBB) benefit from cardiac resynchronization therapy (CRT) is unclear.

Objective: The purpose of this study was to systematically review the published data from randomized clinical trials of CRT on the outcomes in patients with baseline RBBB.

Methods: Randomized controlled trials of CRT in heart failure and left ventricular systolic dysfunction were identified from MEDLINE (1950-2010), EMBASE (1980-2010, week 45), Cochrane Controlled Trials Register (2009), Cochrane Database of Systematic Reviews, National Institutes of Health Clinical Trials.gov database.

Results: A total of 112 references were retrieved. Four publications from five studies reported data on patients with RBBB and were included in this investigation, with 259 patients randomized to CRT and 226 randomized to non-CRT. None of the available data showed more favorable outcomes (soft or hard) in patients with CRT.

Conclusion: None of the available data showed more favorable outcomes with CRT in patients with RBBB. A meta-analysis of RBBB patients from the major CRT trials is urgently needed. Results of the meta-analysis can direct further research, perhaps indicating a need for randomized trials in RBBB. Physicians and patients should be aware of the likely reduced benefit form CRT in patients with RBBB, and this should be factored into decision making. However, until more data are available it is too early to change guidelines.