[Efficacy of metoprolol in prevention of supraventricular arrhythmias after coronary artery bypass grafting].

Atrial fibrillation is in 20-50% the most frequent dysrhythmia after coronary artery bypass grafting (CABG) and a possible cause for hemodynamical complications and prolongation off the medical treatment in patients. Therefore, the effect of beta-blocking with metoprolol for prevention of supraventricular arrhythmias (SVA) was investigated in a prospective and randomized trial. 200 patients after CABG were randomized in a drug and control group (average age 63.2 years, 154 male, 46 female). Patients of the drug group (n=100) were treated with metoprolol (1mg/kg/BW) beginning on day one after operation, whereas patients of the control group (n=100) received therapy only in case of occurrence of atrial fibrillation. ECG, blood pressure, and electrolyte concentrations were measured regularly until the tenth day after surgery. Reasons for exclusion were an ejection fraction (< 30%, SA- and AV-block or simultaneous application of epinephrine and metoprolol. There were no significant differences between the patients of drug and control group with respect to age, sex ejection fraction, previous medication, number and type of bypass grafts, cardiopulmonary bypass time, and perioperative ischemic events. However, a statistically significant difference was seen in the occurrence of supraventricular arrhythmias in both groups, 4 patients of the therapy group (4%) in contrast to 37 patients of the control (37%) developed supraventricular arrhythmias during the postoperative observation period (p<0.0001). Both groups differed in total time of hospital stay by 1.5 days (control group: 9.83+/-2.88 days; drug group: 8.42+/-2.81 days), which was statistically significant (p<0.05). All patients of the drug group could be discharged with a stable sinus rhythm, whereas 7 patients of the control group were discharged with persistent atrial fibrillation. The difference was statistically significant as well (p<0.01). Neither typical side effects of metoprolol, nor AV-blocks, bradycardia (f<60/min) or symptoms of low blood pressure could be observed. The conclusion of this trial is a recommendation for a preventive application of 50mg metoprolol/day after coronary artery bypass surgery, which can reduce the incidence of SVA as well as the hospital stay statistically significant.