Rivero-Ayerza M et al. (2006) Effects of cardiac resynchronization therapy on overall mortality and mode of death: a meta-analysis of randomized controlled trials. Eur Heart J 27: 2682–2688

Cardiac resynchronization therapy (CRT) improves symptoms, quality of life and exercise capacity in patients with advanced heart failure; however, studies to date have been underpowered to assess the effects of CRT on mortality. This meta-analysis by Rivero-Ayerza et al. combines data from 2,371 patients taken from 5 studies that compared the effect on survival of CRT alone versus optimum pharmacologic therapy. The mean age of the study populations included in this meta-analysis ranged from 64 years to 68 years, and the majority of patients were male.

During the mean follow-up period of 18.4 months (range 3.0–29.4 months), patients who received CRT alone had a lower all-cause mortality than those receiving pharmacologic therapy (16.9% vs 20.7%; odds ratio [OR] 0.71, 95% CI 0.57–0.88; P = 0.002). The observed survival benefit of CRT alone was largely attributable to a reduction in death from progressive heart failure (6.7% vs 9.7%; OR 0.62, 95% CI 0.45–0.84; P = 0.003). This reduced progressive heart failure mortality is unsurprising as CRT directly moderates myocardial function and heart failure profile. Rates of sudden cardiac death were similar in the two groups (6.4% vs 5.9%; OR 1.04; P = 0.84).

Despite the observed benefits of CRT, mortality remained high for patients with advanced heart failure. The authors of this study suggest that adding a defibrillator function to a CRT device is likely to further increase survival, and that this warrants further investigation.