Long-Term Patency of Internal Mammary Artery Bypass Grafts Relationship With Preoperative Severity of the Native Coronary Artery Stenosis

Background— Internal mammary artery conduits (IMA) have an excellent long-term patency rate. Nevertheless, graft closure does occur and significantly limits future revascularization options. We sought to investigate the relationship between the long-term patency of IMA with clinical and angiographic parameters. Particularly, the preoperative degree of stenosis of the relevant bypassed coronary vessel was assessed to analyze the importance of chronic competitive flow on the arterial graft closure rate. Methods and Results— Consecutive patients in whom occlusion of at least 1 IMA had been documented at angiography (OCC group) were compared with a group of patients with patent IMA grafts (PAT group). The degree of stenosis in the native coronary artery on which the IMA was placed was analyzed by off-line quantitative coronary angiography. Multivariate stepwise logistic regression was used to identify independent clinical and angiographic predictors of occlusion. The OCC group comprised 96 patients (67±10 yea...