Markers of myocardial ischemia in the evaluation of the effect of left anterior descending coronary artery lesion and collateral circulation on myocardial injury in 1-vessel off-pump coronary bypass surgery

Abstract

Background: The purpose of this study was to use serum markers for myocardial tissue damage to evaluate the effect of the severity of left anterior descending artery (LAD) lesions after 1-vessel off-pump coronary artery bypass grafting.

Methods: A consecutive series of 20 patients with a totally occluded LAD and only retrograde filling (group T; n = 10) or critical stenosis (70%-99%) and only antegrade filling (group C; n = 10) were included in this study. One patient in group C who displayed no increases in the levels of markers for myocardial ischemia was excluded from the study because of the intraoperative repetition of the anastomosis. Creatine kinase activity (CK), CK-MB activity, and CK-MB mass, myoglobin, lactate, and cardiac troponin I (cTnI) concentrations were determined in venous blood samples taken immediately before and after the anastomosis and at 4, 8, 12, 24, and 48 hours postoperatively.

Results: There were no perioperative myocardial infarctions. One patient in group T developed low cardiac output syndrome 48 hours after the operation and died after 1 month. His enzyme levels did not increase in the first 2 days postoperatively. Anastomosis times were similar for the T and C groups (6.85 +/- 0.9 minutes versus 8.4 +/- 2.2 minutes, respectively; P =.069). The levels of all cardiac markers except cTnI increased significantly in the first 24 postoperative hours. CK-MB activity, CK-MB mass concentration, and cTnI concentration were not different between the 2 groups. Four patients in each group were evaluated for the patency of the anastomosis, and all control angiography and myocardial scanning tests showed patent anastomoses and no ischemia.

Conclusions: One-vessel off-pump coronary artery bypass grafting can be performed safely in patients with serious LAD stenosis and borderline antegrade blood flow without the need for any coronary collateral circulation support. A short anastomosis time prevents myocardial injury during off-pump coronary surgery.