A comparison of esmolol and diltiazem for heart rate control during coronary revascularisation on beating heart

This prospective study compared control of heart rate and haemodynamics during coronary artery revascularization without cardiopulmonary bypass using either esmolol or diltiazem. Sixty adult patients with one or two vessel coronary artery disease, were randomly divided into 2 groups. Group A (n=30) received a 50 microg/kg/ loading dose of esmolol followed by a 100 microg/kg/hr infusion, for control of heart rate during surgical anastomosis of the coronary vessel. Group-B (n=30) received 0.15 mg/kg of diltiazem as a loading dose followed by a 5 mg/hr infusion for heart rate control, during the anastomosis. It was seen that heart rate control was better in group A, 51.4 +/- 1.3 beats/min, (p <0.01) than in group B, 69.6 +/- 3.0 beats/min (p <0.05), as compared to baseline values of 80.6 +/- 12.1 beats/min in group A and 82.4 +/- 10.6 beats/min in group B respectively. Systemic vascular resistance and pulmonary artery wedge pressure were unchanged in group A but mean pulmonary artery pressure and pulmonary vascular resistance were significantly raised. Group B patients had decreased systemic vascular resistance, mean pulmonary artery pressure and pulmonary artery wedge pressure, and reduced right ventricular stroke work index at the time of distal coronary anastomosis. We concluded that although esmolol provided dramatically slower heart rates, during surgery, the resulting elevations in mean pulmonary artery pressure and pulmonary vascular resistance would require caution if used in patients with underlying right ventricular dysfunction from ischaemia or infarction. Diltiazem by virtue of its effects on systemic vascular resistance, cardiac output, and lowering of mean arterial pressure may be a better choice in hypertensive patients.