ABSTRACT
We compared the effects of continuous intravenous infusions of nicorandil and diltiazem on left ventricular function, haemodynamics and as anti-ischaemic and anti-arrhythmic agents in 50 patients undergoing off pump coronary artery bypass surgery using arterial conduits. The patients were randomized into two equal groups to receive diltiazem or nicorandil. Both the drugs were given as a continuous infusion in the dose of 1microg/kg/min starting at induction and continued for 24 hours postoperatively. Haemodynamic parameters, cardiac enzyme levels and use of vasoactive agents were studied and compared using ANOVA, unpaired "t" and Fisher's exact tests. The two groups did not differ with respect to preoperative and operative data. Diltiazem group showed lower cardiac index (2.66+/-0.8 and 2.27+/-0.89 L/min/m2) as compared with nicorandil group (3.16+/-0.79 and 2.97+/-1.01 L/min/m2) during revascularisation of anterior (P=0.03) and inferior (P=0.01) circulation respectively. The systemic vascular resistance index was higher (2290+/-699 and 2545+/-911 dync.sec.cm-5.m2) in diltiazem group as compared with nicorandil group (1822+/-532 and 1877+/-548 dyne. sec.cm-5.m2) during revascularization of anterior (P=0.01) and inferior (P=0.002) circulation respectively. The mean pulmonary artery pressure was significantly higher in nicorandil group as compared with diltiazem group during revascularisation of anterior circulation (22.5+/-4.9 and 18.1+/-6.8 mmHg, P=0.01). The patients in the diltiazem group maintained a lower heart rate throughout the study period, but the difference was not statistically significant. None of the patients exhibited any arrhythmia except one in nicorandil group, who developed supraventricular arrhythmia 24 hours postoperatively. Cardiac enzyme levels were found to be similar in the two groups. The present study demonstrates that the anti-ischemic and antiarrythmic effects of diltiazem and nicorandil are comparable, but diltiazem causes a decrease in cardiac index and increase in systemic vascular resistance index during revascularization of anterior and inferior circulation.