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.

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.