Comparison of sotalol and metoprolol in the prevention of atrial fibrillation after coronary artery bypass surgery

New-onset atrial fibrillation (AF) is frequent after coronary artery bypass grafting (CABG), and beta-blockers decrease its incidence. To examine whether a beta-blocker with class III Properties is superior to a pure one, 191 consecutive patients undergoing CABG were randomized to receive oral sotalol, 120 mg daily (n=93), or metoprolol, 75 mg daily (n=98), postoperatively. The doses were adjusted if beta-blockade was inadequate or excessive. AF occurred in 16 (16%) of 98 sotalol patients and in 30 (32%) of 93 metoprolol patients (p<0.01). Symptoms related to beta-blockade or proarrhythmia did not appear. After CABG, sinus heart rate increased in both groups (p < 0.001) but less in the sotalol patients (p < 0.001) throughout the postoperative period. Corrected QT duration (by the Eaten equation) was prolonged after the operation in both groups (p < 0.001), whereas uncorrected QT duration at similar heart-rate levels were prolonged only in sotalol patients (mean increase, 31 ms; 95% confidence interval, 20-42 ms; p < 0.01). Uncorrected QT durations at similar heart-rate levels were longer during sotalol (compared with metoprolol) treatment (p < 0.05). Heart rates or QT durations did not differ between the patients with or without AF. In conclusion, sotalol significantly reduces the incidence of AF after CABG. Although a marked class Ill effect is demonstrated with relatively law doses (as prolonged ventricular repolarization) in direct comparison unbiased by any rate correction, its contribution as an enhanced antifibrillatory mechanism in the postoperative state remains unconfirmed.