Progressive improvement of myocardial perfusion after off-pump revascularization with bilateral internal thoracic arteries: Comparison of early versus 1-year postoperative myocardial single photon emission computed tomography

Objective We evaluated the time course of myocardial perfusion improvement after off-pump revascularization. Methods Seventy-six patients who underwent off-pump coronary bypass with bilateral internal thoracic arteries for revascularization of the left coronary territory were studied. Myocardial single photon emission computed tomography was performed preoperatively and at 3 months and 1 year postoperatively. Myocardial perfusion was quantified with automatic software, and the left coronary territory was divided into 16 segments. As an indicator of the ischemic myocardium, the reversibility score was defined as a measure of rest minus stress perfusion values. A total of 403 segments that showed a reversibility score of 7 or greater preoperatively were included. Results The reversibility score was improved significantly at 3 months postoperatively ( P < .001) and further improved 1 year after the operation ( P < .001). When the patients were divided into 2 groups based on the type of bilateral internal thoracic arteries used (group Y: Y-composite graft, n = 39; group I: bilateral in situ grafts, n = 37), the reversibility score was improved significantly 3 months after the operation ( P < .001) and further improved 1 year after the operation ( P < .001) in both groups. There were no significant differences in the reversibility scores between groups Y and I at postoperative month 3 ( P = .463). The scores approached zero in both groups at 1 year postoperatively (group Y, −1.7% ± 7.9%; group I, 1.3% ± 7.2%). Conclusions The myocardial reversibility score improved greatly during the first 3 months after the operation and further improved until 1 year postoperatively. Perfusion improvement was similar between the Y-composite and bilateral in situ internal thoracic artery grafts in terms of the reversibility score.