Postoperative follow-up of coronary artery bypass patients receiving calcium antagonist diltiazem

Abstract

We performed a prospective, randomized clinical study on 211 elective coronary artery bypass patients to assess the antiischemic and antiarrhythmic effects of the calcium channel blocker diltiazem. Patients received perioperatively continuous 24-hour infusions of either diltiazem (0.1 mg/kg/hour; n = 104) or nitroglycerin (1 μg/kg/minute; n = 107). Patients randomized to the diltiazem group were kept on continuous oral diltiazem medication postoperatively (3×50 mg/day). After a postoperative follow-up period of 2 years, 119 of the 211 patients were available for a clinical evaluation: 56 patients randomized to the diltiazem group and 63 patients randomized to the control group. Twenty patients from the diltiazem and 14 control patients did not follow their medicamentation and were excluded from further study. The two groups did not differ with respect to preoperative and surgical data. Postoperatively, the incidence of atrial fibrillation (4.8% vs 18.6%, p < 0.05) and the frequency of ventricular premature couplets (VPC)/hour (22 ± 6 vs 37 ± 11, p < 0.05), Lown II arrhythmias (VPC >30/hour) (99 ± 19 vs 254 ± 58, p < 0.05), and ventricular runs/hour (7 ± 15 vs 38 ± 25, p < 0.05) were significantly lower in the diltiazem group. Furthermore, patients of the diltiazem group had significantly lower peak values of ischemia-sensitive laboratory parameters: creatine kinase-MB (17.6 ± 14.3 vs 25.3 ± 16.3 U/L, p < 0.05), CK-MB-mass concentration (35.2 ± 38.4 vs 51.5 ± 33.9 μg/L, p < 0.05), and troponin-T (0.98 ± 0.7 vs 1.7 ± 0.8 μg/L, p < 0.05). Two years after coronary artery bypass surgery, fewer patients randomized to the diltiazem group showed signs of cardiac failure (0 vs 6.1%), ST-segment alterations during exercise (5.5% vs 13.2%, p < 0.05), symptoms of angina during exercise (18.5% vs 22.4%, n.s.), atrial fibrillation (0 vs 2.0%), and new left bundle branch block (0 vs 8.2%), compared with controls. It is concluded that the calcium antagonist diltiazem is effective in reducing incidence and extent of arrhythmias and myocardial ischemia perioperatively and provides potent postoperative antiischemic and antiarrhythmic protection in patients after coronary artery bypass surgery.