Rebound vasospasm after coronary revascularization in association with calcium antagonist withdrawal.

Four patients experienced life-threatening coronary vasospasm following discontinuation of calcium channel blocking medication at the time of coronary revascularization. The last dose of the calcium blocker in each instance was administered between 8 and 18 hours before operation. Two of the patients were receiving diltiazem (60 mg four times a day) and 2, nifedipine (20 mg four times a day). During this same period, 16 patients had received diltiazem (12.5% incidence of vasospasm) and more than 100 patients, nifedipine (less than 2% incidence). In 3 of the 4 patients, coronary spasm was identified by electrocardiogram and documented as the cause of ischemia in the distribution of a nondiseased right coronary artery. In the fourth patient, spasm had occurred in the distribution of a bypassed left anterior descending coronary artery. In 2 patients in whom the problem was recognized retrospectively, an infarct developed; 1 patient died. In the 2 patients in whom the problem was apparent prior to infarction, nitroglycerin (1 to 3 micrograms/kg/min, intravenously) and nifedipine (10 mg, sublingually every 4 to 6 hours) successfully reversed the ischemic process. The routine administration of calcium at the completion of coronary revascularization may be ill-advised in patients in whom calcium channel blockers have been utilized. Postoperative therapy of this condition with intravenous administration of nitroglycerin and sublingual administration of nifedipine seems to be effective when instituted early.