Prevention of Atrial Fibrillation or Flutter by Acebutolol After Coronary Bypass Grafting PATRICK DAUDON, MD, THIERRY CORCOS, MD, IRADJ GANDJBAKHCH, MD, JEAN-PIERRE LEVASSEUR, MD, ANNIK CABROL, MD, and CHRISTIAN CABROL, MD Supraventricular tachyarrhythmias are common af- ter coronary artery bypass graft surgery (CABG) and may have deleterious hemodynamic conse- quences. To determine if acebutolol, a cardioselec- tive/~-blocking drug, prevents such tachyarrhyth- mias after CABG, 100 consecutive patients, aged 30 to 77 years (mean 4- standard deviation 53 :E 9), were entered into a randomized, controlled study; Exclusion criteria were: contraindications to /~-blocking drugs, left ventricular aneurysm, major renal failure, history of cardiac arrhythmia and car- diac arrhythmia during the immediate postoperative period. From 36 hours after surgery until discharge (usually on the seventh day), 50 patients were giv- en 200 mg of acebutolol (or 400 mg if weight was more than 80 kg) orally twice a day (dosage then modified to maintain a heart rate at rest between 60 and 90 beats/min). The 50 patients in the control group did not receive/~-blocking drugs after CABG. The 2 groups were comparable in angina functional class, ejection fraction, number of diseased vessels, antianginal therapy before CABG, number of by- passed vessels and duration of cardiopulmonary by- pass. All patients were clinically evaluated twice daily and had continuous electrocardiographic moni- toring and daily electrocardiograms. A 24-hour con- tinuous electrocardiogram was recorded in the last 20 patients. Atrial tachyarrhythmias developed in 20 patients (40%) in the control group (17 patients had atrial fibrillation and 3 patients atrial flutter), but in none in the acebutolol group (p <0.001). This study reveals the efficacy of acebutolol in pre- vention of supraventricular tachyarrhythmias after CABG. (Am J Cardiol 1986;58:933-936) S upraventricular tachyarrhythmias frequently com- plicate the postoperative course of patients undergoing coronary artery bypass grafting {CABG}; they can oc- cur in 1I% to 100% of such patients.H3 These tachyarrhythmias may have deleterious hemodynamic effects and may require urgent drug therapy or even electric cardioversion. Their higher frequency in pa- tients ~: wh~ have B-blockade therapy discontinued before CABG suggests that B-blockade withdrawal contributes to the high incidence of postoperative ar- rhythmias. 5,7,8,14 Acebutolol is a cardioselective fl- adrenoceptor blocking agent with membrane-stabiliz- ing activity and moderate intrinsic sympathomimetic activity. It has a relatively shoi~thalf-life {4 ± I hours}, but its acetylated metabolite, diacetolol, also has From the Department of Cardiovascular Surgery, H6pital de la Piti~, and the universit~ Pierre et Marie Curie, Paris, France. Manuscript received FebrUary 24, 1986; revised manuscript re- ceived June 23, 1986, accepted July 2, 1986. Address for reprints: Patrick Daudon, MD, Service de Chir- urgie Cardio-vasculaire, H6pital de la Piti~; 83, Boulevard de l'H6pitai, 75651 Paris C6dex 13, France. potent B-blocking properties. 15,1B We evaluated the efficacy and safety of acebutolol in the prophylactic treatment of supraventricular tachyarrhythmias after CABG. Methods Patients: One hundred patients undergoing elec- tive CABG without additional cardiac surgical proce- dures (such as valve replacement or ventricular aneu- rysmectomy} were included. Patients were excluded if they had any of the following: (1} contraindication to B" blocking drugs, such as second- or third-degree atrio- ventricular block, bronchial asthma, severe chronic Obstructive lung disease, diabetes mellitus requiring drug therapy or suspected variant angina; (2} left ven- tricular aneurysm; (3) maj Or renal failure; (4} history of cardiac arrhythmias; (5} cardiac arrhythmias during the immediate (36 hours) postoperative period; and {6} low cardiac output still requiring catecholamine sup- port at 36 hours after surgery. Study design: All patients received their antiangi- nal therapy at full dose until the operation, including the morning of surgery. Patients included in the study 933