Relation between functional coronary artery stenosis and graft occlusion after coronary artery bypass grafting

This study was conducted to evaluate graft patency rates during the 5 years after coronary artery bypass grafting according to the functional significance of the coronary artery stenosis, as determined by myocardial single-photon-emission computed tomography.

Two hundred ninety-five patients who underwent coronary artery bypass grafting using Y-composite grafts based on the in situ left internal thoracic artery, and in whom preoperative stress/rest myocardial single-photon-emission computed tomography and 1-year angiographies were available were enrolled. Seven hundred sixty-nine and 262 distal anastomoses were constructed to ischemic and nonischemic areas, respectively. One-year and 5-year angiographic occlusion rates were evaluated in all and 80.3% of study patients, respectively. Factors associated with graft occlusion were evaluated using generalized linear mixed-effects models.

Overall 1- and 5-year graft occlusion rates were 4.3% (44 of 1031 distal anastomoses) and 5.5% (45 out of 820), respectively. The occlusion rates of grafts bypassed to vessels with functionally significant and insignificant stenosis were 2.7% (21 out of 769) and 8.8% (23 out of 262) at 1 year and were 4.0% (25 out of 618) and 9.9% (20 out of 202) at 5 years, respectively. Graft occlusion during the 5 years after coronary artery bypass grafting was associated with the functional significance of coronary artery stenosis (odds ratio, 0.50; 95% confidence interval, 0.28-0.92). The odds ratio of the graft occlusion according to functional ischemia was lower and significant in grafts to arteries with intermediate stenosis (stenosis ≥70% but <90%; odds ratio, 0.34; 95% confidence interval, 0.13-0.93) whereas it was higher and insignificant in grafts to arteries with severe stenosis (≥90% stenosis; odds ratio, 0.76; 95% confidence interval, 0.33-1.72).

Graft occlusion during the 5 years after coronary artery bypass grafting was associated with the functional significance of coronary artery stenosis, particularly when the stenosis degree was not severe.