Background: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with advanced symptoms of heart failure.
Purpose: To assess the benefits and harms of CRT in patients with advanced heart failure and those with less symptomatic disease.
Data Sources: A search of electronic databases (1950 to December 2010), hand-searching of reference lists, and unpublished data from principal investigators. Searches were not limited to the English language.
Study Selection: Randomized, controlled trials of CRT compared with usual care and right or left ventricular pacing in adults with heart failure and a left ventricular ejection fraction of 0.40 or less.
Data Extraction: Two reviewers performed independent study selection, data abstraction, and quality assessment by using the Cochrane tool for assessing risk for bias.
Data Synthesis: There were 9082 patients in 25 trials. In patients with New York Heart Association (NYHA) class I and II symptoms, CRT reduced all-cause mortality (6 trials, 4572 participants; risk ratio [RR], 0.83 [95% CI, 0.72 to 0.96]) and heart failure hospitalizations (4 trials, 4349 participants; RR, 0.71 [CI, 0.57 to 0.87]) without improving functional outcomes or quality of life. In patients with NYHA class III or IV symptoms, CRT improved functional outcomes and reduced both all-cause mortality (19 trials, 4510 participants; RR, 0.78 [CI, 0.67 to 0.91]) and heart failure hospitalizations (11 trials, 2663 participants; RR, 0.65 [CI, 0.50 to 0.86]). The implant success rate was 94.4%; peri-implantation deaths occurred in 0.3% of trial participants, mechanical complications in 3.2%, lead problems in 6.2%, and infections in 1.4%.
Limitation: Subgroup analyses were underpowered and lack data for persons with NYHA class I symptoms, atrial fibrillation, chronic kidney disease, or right bundle branch block.
Conclusion: Cardiac resynchronization therapy is beneficial for patients with reduced left ventricular ejection fraction, symptoms of heart failure, and prolonged QRS, regardless of NYHA class.
Primary Funding Source: None.