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 diltiazem reduces the occurrence and extent of postoperative myocardial ischemia. However, recent reports also mention nitroglycerin as the drug of choice to prevent conduit spasm after coronary bypass grafting. The diagnosis of myocardial ischemia in the perioperative setting is still problematic. Dobutamine stress echocardiography (DSE) is an established technique that combines inotropic stimulation with real-time myocardial imaging and delineates normal and abnormal regional contraction patterns. We assessed the perioperative 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 circulation until 24 h postoperatively. Dobutamine stress echocardiography was performed in a stepwise fashion 2 to 3 h after elective coronary artery bypass grafting.

RESULTS

In 42 of 49 patients, dobutamine stress echocardiography either reached a level of 40 micrograms/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 electrocardiographic 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 postoperatively. Heart rate was significantly lower in the diltiazem group (p = 0.0003).

CONCLUSIONS

Under conditions of hemodynamic stress, DSE revealed no significant difference between diltiazem and nitroglycerin with regard to renewed ischemia.