Diltiazem versus nitroglycerin for myocardial protection following coronary artery bypass grafting as assessed by dobutamine stress echocardiography

Background: Perioperative infusion of the calcium channel antagonist diltia zem reduces the occurrence and extent of postoperative myocardial ischemia. However, recent reports also mention nitroglycerin as the drug of choice t o prevent conduit spasm after coronary bypass grafting. The diagnosis of my ocardial ischemia in the perioperative setting is still problematic. Dobuta mine stress echocardiography (DSE) is an established technique that combine s inotropic stimulation with real-time myocardial imaging and delineates no rmal and abnormal regional contraction patterns. We assessed the perioperat ive anti-ischemic effects of diltiazem and nitroglycerin during hemodynamic stress using DSE. Methods: 50 adult patients were included in a prospective randomized study. Diltiazem or nitroglycerin was used from the onset of extracorporeal circu lation until 24 h postoperatively. Dobutamine stress echocardiography was p erformed in a stepwise fashion 2 to 3 h after elective coronary artery bypa ss grafting. Results: In 42 of 49 patients, dobutamine stress echocardiography either re ached a level of 40 mug/kg/min dobutamine or achieved the target heart rate . One patient improved in terms of segmental wall motion abnormalities and three patients developed new abnormalities without corresponding electrocar diographic changes. Analysis of ischemia-sensitive parameters showed lower creatine kinase MB ( p = 0.032) and troponin I levels (p = 0.1) in the diltiazem group 24 h post operatively. Heart rate was significantly lower in the diltiazem group (p=0 .0003). Conclusions: Under conditions of hemodynamic stress; DSE revealed no signif icant difference between diltiazem and nitroglycerin with regard to renewed ischemia.