Presence and development of atrial fibrillation in chronic heart failure

Abstract

Background: Atrial fibrillation is common in heart failure, but data regarding beta-blockade in these patients and its ability to prevent new occurrence of atrial fibrillation are scarce. Methods: Baseline ECGs in MERIT-HF were coded regarding baseline rhythm, and outcome was analyzed in relation to rhythm. Occurrence of atrial fibrillation during follow-up was also analyzed. Results: At baseline atrial fibrillation was diagnosed in 556patients (13.9%). Mean metoprolol CR/XL dose in patients in atrial fibrillation (154 mg) and sinus rhythm (158 mg) was similar, as well as decrease in heart rate (14.8 and 13.7 bpm, respectively). Only 61 (total of 362) deaths occurred in those in atrial fibrillation at baseline, 31 on placebo and 30 on metoprolol (RR 1.0; 95% CI 0.61 -1.65). During follow-up, new atrial fibrillation was observed in 85 patients on placebo and 47 patients on metoprolol (RR 0.53; 95% CI 0.37 -0.76; p = 0.0005). Conclusion: First, given the wide confidence interval, it was impossible to detect an interaction between metoprolol and mortality in patients with atrial fibrillation and heart failure. Second, in patients with sinus rhythm at baseline, metoprolol reduced the incidence of atrial fibrillation during follow-up. However, we must be extremely cautious in over-interpreting effects in these subgroups.

Rate control in atrial fibrillation, insight into the RACE II study

“…Apparently, a resting heart rate below 110 beats per minute was low enough to prevent an increased number of hospitalisations for heart failure. This is in line with the notion that beta-blockers do not improve the prognosis of patients with heart failure who have atrial fibrillation [41,42].…”

Carvedilol Compared With Metoprolol Succinate in the Treatment and Prognosis of Patients With Stable Chronic Heart Failure

“…8 Then again, a retrospective analysis of the MERIT-HF study did not detect an effect of treatment with metoprolol succinate on mortality in the subset of CHF patients with atrial fibrillation. 49 Finally, it has been reported that carvedilol may be preferable to metoprolol tartrate to prevent the development of renal failure in patients with CHF. 50 These studies, however, included few patients, and in some studies follow-up was short.…”

A frequent Gene Polymorphism Affecting the Heart-rate Response to Carvedilol

“…In fact, beneficial effects of b-blockers on outcome in patients with heart failure and AF have never been prospectively studied. Retrospective analyses of large-outcome studies suggested significant benefits of treatment with carvedilol [13] and formally not with bisoprolol [19] or metoprolol [20]. On the other hand, a retrospective study in patients with heart failure observed an association of the Arg389Arg (plus Gln27/X for the b2-adrenoceptor) genotype with a twofold higher mortality risk in patients treated with carvedilol, but not with metoprolol [21].…”