Perioperative Beta Blockade with Propranolol: Reduction in Myocardial Oxygen Demands and Incidence of Atrial and Ventricular Arrhythmias

Abstract

To determine the effect of beta blockade with propranolol on myocardial oxygen demands and postoperative arrhythmias in patients having coronary bypass operations, 50 patients with chronic stable angina undergoing operation were randomized in a double-blind fashion to receive either propranolol (60 mg every 6 hours) or a placebo. Drug administration began 24 to 48 hours prior to operation and continued through the operative period and for one month after operation. There were no deaths. Two perioperative myocardial infarctions occurred, both in patients receiving a placebo. Myocardial oxygen demand as measured by the rate-pressure product (heart rate × mean arterial pressure) was significantly reduced during induction of anesthesia (7,658 ± 451 versus 5,786 ± 340; p < 0.002) and during sternotomy (8,400 ± 550 versus 6,756 ± 384; p < 0.02) in propranolol-treated patients. In the first two postoperative days, nitroprusside was required for control of hypertension of 10 patients in the placebo group but in only 3 patients given propranolol ( p < 0.05). Postoperatively, 15 of the 26 patients who received a placebo had 45 episodes of arrhythmia. Seven of the 24 propranolol-treated patients had 17 episodes ( p < 0.04). We conclude that propranolol given perioperatively in doses large enough to induce beta blockade significantly reduces myocardial oxygen demands in the vulnerable period during induction of anesthesia and sternotomy, reduces the need for antihypertensive therapy in the immediate postoperative period, and causes a marked reduction in the incidence and frequency of both supraventricular and ventricular arrhythmias in the postoperative period.