Background: Atrial fibrillation (AF) is frequent in patients with chronic heart failure (CHF). Experimental and small patient studies have demonstrated that blocking the renin-angiotensin-aldosterone system may prevent AF. In the CHARM program, the effects of the angiotensin receptor blocker candesartan on cardiovascular mortality and morbidity were evaluated in a broad spectrum of patients with symptomatic CHF. CHARM provided the opportunity to prospectively determine the effect of candesartan on the incidence of new AF in this CHF population.
Methods: 7601 patients with symptomatic CHF and reduced or preserved left ventricular systolic function were randomized to candesartan (target dose 32 mg once daily, mean dose 24 mg) or placebo in the 3 component trials of CHARM. The major outcomes were cardiovascular death or CHF hospitalization and all-cause mortality. The incidence of new AF was a prespecified secondary outcome. Median follow-up was 37.7 months. A conditional logistic regression model for stratified data was used.
Results: 6379 patients (83.9%) did not have AF on their baseline electrocardiogram. Of these, 392 (6.15%) developed AF during follow-up, 177 (5.55%) in the candesartan group and 215 (6.74%) in the placebo group (odds ratio 0.812, 95% CI 0.662-0.998, P = .048). After adjustment for baseline covariates, the odds ratio was 0.802 (95% CI 0.650-0.990, P = .039). There was no heterogeneity of the effects of candesartan in preventing AF between the 3 component trials (P = .57).
Conclusions: Treatment with the angiotensin receptor blocker candesartan reduced the incidence of AF in a large, broadly-based, population of patients with symptomatic CHF.