Effects of the postoperative administration of diltiazem on renal function after coronary artery bypass grafting

Radial artery grafts are used for coronary artery bypass grafting (CABG), and postoperative antispasm therapy with diltiazem is performed widely. Some investigators have warned that diltiazem administration after cardiac surgery is harmful to renal function. We designed a retrospective study to investigate the renal and hemodynamic effects of the postoperative administration of diltiazem in patients undergoing CABG.

Subjects were 90 consecutive CABG patients. All were treated with diltiazem during surgery (a 0.1 mg/kg bolus injection followed by continuous infusion at 2 microg x kg(-1) x min(-1)). In the 50 patients (diltiazem group) with a radial artery graft, intravenous diltiazem administration was continued until the oral intake of diltiazem (90 mg/d) was begun to avoid graft spasms. In the remaining 40 patients without a radial artery graft, diltiazem was not continued postoperatively (control group). Postoperative renal function, assessed by serum creatinine level and creatinine clearance, and hemodynamic variables (heart rate, arterial pressure, pulmonary wedge pressure, cardiac index, left ventricular stroke work index) was compared between the two groups.

Renal function: Serum creatinine concentrations on postoperative days 1 through 7 were lower, and the endogenous creatinine clearance in the early postoperative period was higher in diltiazem group than in control group, although the differences were not significant. Hemodynamics: Heart rate was lower in diltiazem group than in the control group, but blood pressure, pulmonary wedge pressure, cardiac index, left ventricular stroke work index, and urinary output were similar between the groups.

Our results confirmed that intravenous diltiazem treatment in patients undergoing CABG is not harmful to renal function.