COMPARISON OF PERIOPERATIVE MYOCARDIAL PROTECTION WITH NIFEDIPINE VERSUS NIFEDIPINE AND METOPROLOL IN PATIENTS UNDERGOING ELECTIVE CORONARY-ARTERY BYPASS-GRAFTING

A randomized study was performed on 70 patients undergoing elective co ronary bypass grafting to examine whether the combined infusion of the calcium channel blocker nifedipine (10 mu g/kg per hour) and the beta (1)-blocker metopropol (12 mu g/kg per hour, n = 34) reduces the preva lence of perioperative myocardial ischemia and arrhythmia, The control group received nifedipine alone (n = 36), In both groups the infusion was started from the onset of extracorporal circulation and maintaine d over a period of 24 hours, Repeated 12-lead electrocardiographic and 3-channel Holter monitor recordings for 48 hours were used to define perioperative myocardial ischemia (transient ischemic event, myocardia l infarction) and arrhythmias (sinus tachycardia, supraventricular tac hycardia, atrial flutter/fibrillation, ventricular tachycardia), Hemod ynamic parameters were repeatedly assessed for 24 hours and serum enzy me levels (creatine kinase, MB isoenzyme of creatine kinase) for up to 36 hours after the operation, The two groups did not differ significa ntly,vith respect to preoperative anamnestic and surgical data, No sig ns of perioperative myocardial infarction were detected in either grou p. However, a significantly lower incidence of transient ischemic epis odes was observed in the nifedipine-metoprolol group than in the nifed ipine group (3% vs 11%; p < 0.05), In addition, there was a tendency t oward lower creatine kinase MB levels and peak values of creatine kina se and creatine kinase MB in the nifedipine-metoprolol group. With reg ard to perioperative arrhythmias, there was a significantly lower inci dence of sinus tachycardia and atrial flutter/fibrillation in the nife dipine-metoprolol group (9% and 6%) than in the nifedipine group (33% and 27%, p < 0.05), In addition, postoperative heart rate was lower in the nifedipine-metoprolol group starting from the sixth hour after re lease of the aortic crossclamp (p < 0.05 and p < 0.01, respectively). No other hemodynamic parameters showed significant differences between the two groups and all returned to preoperative levels within 24 hour s, In conclusion, perioperative application of nifedipine and metoprol ol in patients undergoing elective coronary bypass grafting reduces th e prevalence of perioperative myocardial ischemia and arrhythmias with out significant negative inotropic effects. The combined infusion of t he two drugs appears superior to nifedipine alone in preventing periop erative myocardial ischemia and reducing reperfusion-induced arrhythmi as.