Aims: Cardiac resynchronization therapy (CRT) has been shown to improve symptoms and exercise tolerance in patients with advanced heart failure (HF). However, studies were underpowered to address its effect on overall mortality. To evaluate whether CRT alone (without a combined defibrillator function) reduces overall mortality as compared with optimal pharmacological therapy, and how it affects the mode of death in patients with advanced HF.
Methods and results: Public domain databases were systematically searched. Randomized controlled studies that evaluated the effects of CRT alone in patients with advanced HF and a depressed left ventricular systolic performance were selected for this analysis. Trials, which did not independently report data on CRT alone or had a follow-up period of less than 3 months, were excluded. Five studies were identified and analyzed. They included a total of 2371 patients, 1028 controls and 1343 CRT-treated patients. Pooled analysis demonstrated that CRT alone, as compared with optimal medical therapy, significantly reduced all-cause mortality by 29% [16.9 vs. 20.7%; odds ratio (OR), 0.71; 95% confidence interval (CI), 0.57-0.88] and mortality due to progressive HF by 38% (6.7 vs. 9.7%; OR, 0.62; 95% CI, 0.45-0.84). No effect on sudden cardiac death (SCD) was observed with CRT (6.4 vs. 5.9%; OR, 1.04; 95% CI, 0.73-1.22).
Conclusions: CRT alone as compared with optimal medical therapy reduces all-cause mortality in patients with advanced HF. It predominantly reduces worsening HF mortality, not affecting SCD.