Efficacy of metoprolol in prevention of supraventricular arrhythmias aftercorollary artery bypass grafting

Atrial fibrillation is in 20-50 % the most frequent dysrhythmia after coron ary artery bypass grafting (CABG) and a possible cause for hemodynamical co mplications and prolongation of the medical treatment in patients. Therefor e, the effect of beta-blocking with metoprolol for prevention of supraventr icular arrhythmias (SVA) was investigated in a prospective and randomized t rial. 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 (1 mg/kg/BW) beginning on day one afte r operation, whereas patients of the control group (n = 100) received thera py only in case of occurrence of atrial fibrillation. EGG, 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. The re were no significant differences between the patients of drug and control group with respect to age, sex, ejection fraction, previous medication, nu mber and type of bypass grafts, cardiopulmonary bypass time, and perioperat ive ischemic events. However, a statistically significant difference was se en in the occurrence of supraventricular arrhythmias in both groups, 4 pati ents of the therapy group (4 %) in contrast to 37 patients of the control ( 37 %) developed supraventricular arrhythmias during the postoperative obser vation 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 sinusrhythm, whereas 7 patient s of the control group were discharged with persistent atrial fibrillation. The difference was statistically significant as well (p < 0.01). Neither t ypical 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 50 mg metoprolol /day after coronary artery bypass surgery, which can reduce the incidence o f SVA as well as the hospital stay statistically significant.