Two-year assessment by exercise thallium scintigraphy of myocardial revascularization using bilateral internal mammary and gastroepiploic arteries.

OBJECTIVE

To assess the blood flow supply offered to the myocardium by surgical revascularization using bilateral internal mammary (IMAs) and gastroepiploic (GEA) arteries.

METHODS

Two-year assessment by exercise thallium myocardial scintigraphy without medical treatment was performed in 122 patients (mean age 61 +/- 9 years) who underwent coronary artery bypass grafting (CABG) with exclusive use of IMAs and GEA. Usually, the right IMA was used to bypass the left anterior descending coronary artery, and the left IMA to bypass the diagonal and the marginal arteries as a sequential graft if required. The GEA was used to bypass the right coronary artery (RCA) in 50 patients and its posterior branches in 72 patients.

RESULTS

During maximal or submaximal exercise stress testing, 119 patients (98%) were asymptomatic and 26 patients (21%) exhibited moderate ischemic ECG modifications which were correlated (P < 0.01) with incomplete revascularization and with the use of GEA to bypass the RCA. A third of patients had moderate ischemic thallium defects on exercise reversible after redistribution (anterior, 10; lateral, 2; inferior, 28). Silent residual myocardial ischemia detected by thallium scintigraphy was correlated (P < 0.001) with ECG modifications and incomplete revascularization; and inferior thallium defects were more frequent when GEA bypassed the RCA (P < 0.05). However, 26% of patients had residual ischemia despite a complete revascularization, and in at least 18% of cases for GEA and 8% for right IMA, arterial graft blood flow was insufficient at maximum exercise level and caused silent residual myocardial ischemia detected by thallium scintigraphy.

CONCLUSIONS

Myocardial revascularization using bilateral IMAs and GEA offers a satisfactory myocardial perfusion in the majority of cases; however silent residual myocardial ischemia was detected in a third of patients and was related to incomplete revascularization and to insufficient blood flow supply probably due to small diameter of the arterial grafts.