Improved myocardial perfusion and thickening after off-pump revascularization: 5-year follow-up

Late improvements in myocardial perfusion and thickening after off-pump revascularization were evaluated during a 5-year follow-up by myocardial single photon emission computed tomography.

Between 2001 and 2003, 68 patients who underwent off-pump coronary artery bypass grafting using bilateral internal thoracic artery Y-composite (group Y, n = 41) or in situ (group I, n = 27) grafts for revascularization of the left coronary artery territory were enrolled. Myocardial single photon emission computed tomography was performed preoperatively and at 3 months, 1 year, and 5 years postoperatively. A 20-segment model was adopted. As an indicator of ischemic myocardium, the reversibility score was defined as a measure of rest minus stress perfusion values. A total of 374 segments that showed a reversibility score of > or = 7 preoperatively were included. Z values for thickening were calculated as observed values minus reference values divided by the reference standard deviation. Mixed-model analysis was used to compare the two groups with respect to the time sequences of myocardial reversibility scores and Z values.

Postoperative reversibility scores improved significantly at 3 months (p < 0.001) and further at 5 years (p = 0.030). Postoperative Z values improved significantly at 3 months (p < 0.001), between 1 year and 5 years (p = 0.006), and further at 5 years (p = 0.004). In the mixed models, there were no significant differences in reversibility scores and Z values between groups Y and I at any point.

Reversibility scores and thickening gradually improved during 5 years after off-pump revascularization using bilateral internal thoracic arteries. No significant differences were observed between Y-composite and bilateral in situ grafts in terms of reversibility score and thickening improvement at 5 years postoperatively.