Graft patency after off-pump coronary artery bypass surgery is inferior even with identical heparinization protocols: Results from the Danish On-pump Versus Off-pump Randomization Study (DOORS)

Objective: To determine whether graft patency after on-pump and off-pump coronary artery bypass surgery is similar when performed using the same heparinization protocol. Methods: In a randomized, controlled, multicenter trial, 900 patients more than 70 years of age received either on-pump or off-pump coronary artery bypass surgery. Heparin was given to achieve an activated clotting time of 400 seconds before arteriotomy in both groups. After the procedure, protamine sulfate was given to revert the activated clotting time to less than 120 seconds. Coronary angiography was performed 6 months after the operation and graft patency was assessed by independent blinded observers. Results: A total of 481 patients underwent angiography. In the off-pump group, 561 (79%) of 710 grafts were open, 65 (9%) were stenotic, and 84 (12%) were occluded. In the on-pump group, 549 (86%) of 650 grafts were open, 38 (5%) were stenotic, and 63 (9%) were occluded. The difference between the proportion of open grafts was statistically significant in favor of on-pump surgery (P = .01). The proportion of open left internal thoracic artery grafts was 95% in both groups. Perioperative use of intracoronary shunts did not increase the risk of stenosis of the coronary artery distal to the anastomosis. Conclusions: Despite comparable heparinization, graft patency after off-pump surgery was inferior to that after on-pump surgery.