Factors influencing graft patency
Patency rates of coronary artery grafts depend on many factors: some, to be sure, relate to operative technique and surgical experience, but more influential perhaps are the quality of runoff, the graft flow rate, the type of bypass conduit, etc. On the other hand, while factors responsible for early graft closure (Vg thrombosis) may differ in some respect from those associated with late graft failure (Vg intimal hyperplasia, atherosclerosis), some conditions such as quality of arterial bed and, to a certain extent, surgical technique appear to influence both early and late results.
In comparing our early experience to our more recent one at the Montreal Heart Institute, it became evident that graft patency improved considerably over the years. Thus, cumulative patency rates at 2 weeks and 1 year were 65% in the first 300 patients and 80% in the next 300 patients. This was believed due to improvement in the surgical technique and not to the selection of patients who differed, for instance, in the quality of runoff, left ventricular function, or symptoms.
Factors which were found to intervene both early and late after operation, irrespective of surgical experience, were the following:
arterial runoff (600 cases); good runoff, cumulative patency rate at 1 year: 80%; poor runoff, 38.1% (p < 0.001);
size of artery >2 mm, 79.5%; <1.5, 47.2% (p < 0.001);
graft flow >50 ml/min, 89.1%; <50, 50.2% (p < 0.001);
site of anastomosis mid LAD, 78.7%; distal LAD, 46.4% (p < 0.01).
Conversely, degree . . .