ObjectiveTo evaluate immediate outcomes of 8-0 Prolene sutures for distal anastomosis during off-pump coronary artery bypass grafting (OPCAB). MethodsA total of 101 patients who underwent OPCAB in Department of Cardiac Surgery of Beijing Anzhen Hospital in 2010 and 2012 respectively were enrolled in this study. There were 87 male and 14 female patients with their age of 46-82 (61.35±8.24)years. All the 36 patients in 2010 received 7-0 Prolene sutures for distal anastomosis, and the 65 patients in 2012 received 8-0 Prolene sutures for distal anastomosis. After anastomosis, transit time flow measurement was used to measure blood flow indexes of graft vessels[left internal mammary artery (LIMA)and saphenous vein (SV)] including blood flow volume (BFV), pulsatility index (PI)and diastolic filling fraction (DF), which were compared between patients receiving 7-0 and 8-0 Prolene sutures. ResultsBFV of LIMA grafts with 8-0 Prolene sutures (n=44)was significantly larger than that with 7-0 Prolene sutures (n=30)[ (33.70±21.13)ml/min vs. (27.50±17.34)ml/min, P=0.032], while PI of LIMA grafts with 8-0 Prolene sutures was significantly smaller than that with 7-0 Prolene sutures (2.15±0.69 vs. 2.58±1.01, P=0.047). BFV and PI of SV grafts with 8-0 Prolene sutures (n=21) were not statistically different from those with 7-0 Prolene sutures (n=6)[ (34.19±16.00)ml/min vs. (29.00±15.48)ml/min, P > 0.05;2.07±0.53 vs. 1.95±0.55, P > 0.05]. DF of all the grafts was greater than 50%, and there was no statistical difference in DF between the 2 groups (P > 0.05). Conclusion8-0 Prolene sutures for LIMA-to-left anterior descending artery can improve BFV and decrease PI of LIMA grafts, which reflects better immediate graft patency of the distal anastomosis and helps improve surgical success rate and long-term prognosis.