How serious is a proximal occlusion of a posterolateral sequential bypass?

The sequential coronary bypass, despite having several demonstrated benefits, has been criticized for being solely dependent upon 1 proximal anastomosis. The aim of this study was to evaluate the danger of a proximal occlusion of a posterolateral sequential bypass graft. Between 1 January 1984 and 31 December 1994, 3,203 patients underwent primary coronary artery bypass grafting with at least 1 sequential vein bypass graft (780 patients received 1 sequential graft and 2,423 patients received 2). There were 5,626 sequential bypass grafts: 3,492 posterolateral (62%) and 2,134 antero-latero-septal (38%) grafts. There were 73 hospital deaths (2.3%). Follow-up was performed on 3,130 hospital survivors (5,504 grafts), for an average of 59 +/- 36 months (range, 1 to 11 years). During follow-up, a total of 250 symptomatic sequential graft occlusions occurred in 250 patients (8.0%). Only 23 (0.7%) of the surviving 3,431 posterolateral sequential bypass grafts had symptomatic proximal occlusion, 35.9 +/- 5.9 months postoperatively, with all the distal anastomoses remaining patent. Twenty-two of the patients so affected presented with angina and 1 with myocardial infarction. There was no mortality. In 12 patients (52%), medical treatment was sufficient, while 11 patients (48%) underwent successful repeat coronary revascularization. The operation consisted of a simple vein graft from the aorta to the distally patent sequential graft in all patients. Four patients had additional coronary artery bypass grafting due to progression of the disease. The 10-year survival rate was 86.7%. Symptomatic occlusion of only the proximal segment of posterolateral sequential bypass grafts occurs rarely and has a low risk of myocardial infarction and mortality, provided that the terminal anastomosis is with a high-flow vessel.