Atrial fibrillation (AF) occurs frequently soon after coronary artery bypass grafting (CABG) and often results in increased mortality and morbidity, particularly in patients with heart failure. New-onset AF is also a common event in the early period after discharge from a cardiac surgery clinic. Current guidelines recommend β blockers as first-line medication for the prevention of AF after CABG. In this prospective study, we investigated the effectiveness of the highly selective β1 receptor antagonist bisoprolol compared to the less selective β blocker carvedilol in preventing postdischarge AF after CABG in patients with decreased left ventricular function. Three hundred twenty patients (231 men, 89 women, mean age 66 ± 10 years) with ejection fraction <40% who underwent CABG and were then referred to an in-hospital cardiac rehabilitation program were randomized to receive bisoprolol (n = 160) or carvedilol (n = 160) starting 4 to 5 days after surgery. Bisoprolol was started at 1.25 mg 1 time/day and carvedilol was started 3.125 mg 2 times/day. All patients underwent continuous telemetric electrocardiographic monitoring for 5 days after entry in the study and thereafter 2 times/day routinely up to hospital discharge. During follow-up, 23 patients (14.6%) in the bisoprolol group and 37 patients (23%) in the carvedilol group developed AF (relative risk 0.6, confidence interval 0.4 to 0.9, p = 0.032). Twenty-six percent of all AF episodes were asymptomatic. At the 4-week outpatient visit, those in the bisoprolol group showed a significantly greater decrease in heart rate, being in sinus rhythm or AF (-15.6 ± 3 vs -9.4 ± 3 beats/min, p = 0.021), whereas changes in systolic and diastolic blood pressures did not differ significantly. In conclusion, bisoprolol is more effective than carvedilol in decreasing the incidence of postdischarge AF after CABG in patients with decreased left ventricular function.
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