Postoperative Treadmill Performance and Graft Patency after Myocardial Revascularization

In a prospective study, a random selection of 122 patients who had coronary artery bypass grafting were studied angiographically and given treadmill tests preoperatively and one year after operation, regardless of their symptoms. A total of 397 grafts were performed (average, 3.3 grafts per patient) on all primary and secondary coronary vessels deemed graftable. Complete coronary revascularization (grafts to vessels 1.5 mm or more in diameter with 50% or greater stenosis) was achieved in 104 patients (85%); 18 patients (15%) were considered incompletely revascularized. One hundred sixteen of the 397 grafts (29%) were to the left anterior descending (LAD) coronary artery, 99 (25%) to the right coronary artery, 126 (32%) to the obtuse marginal branch, 52 (13%) to the diagonal branch of the LAD coronary artery, and 4 (1%) to the septal coronary arteries. Overall results showed that patients with positive postoperative treadmill tests had a graft patency of 64%, compared with 86% for patients with negative treadmill tests ( p < 0.001). Completely revascularized patients with all grafts patent had a 4.8% (3/62) incidence of positive treadmill performance, compared with 60% (6/10) for incompletely revascularized patients with all grafts patent ( p < 0.001). Completely revascularized patients with positive treadmill tests had a graft patency of 58% (45/78), while those with negative treadmill evaluations had a graft patency of 86% (227/264) ( p < 0.001). The patency rate for incompletely revascularized patients with positive treadmill performance was 78% (25/32) and 87% (20/23) for those with negative treadmill performance. This difference was not statistically significant. This study shows that postoperative treadmill performance is highly dependent on completeness of revascularization and graft patency. It therefore supports the prognostic importance of regular treadmill exercise testing to monitor continued graft patency.