Association Between Preoperative Aspirin-dosing Strategy and Mortality After Coronary Artery Bypass Graft Surgery

To determine whether preoperative aspirin-acetylsalicylic acid (ASA)-timing or dose independently affects 30-day all-cause mortality.

Preoperative ASA administration is associated with reduced morbidity and mortality after coronary artery bypass graft (CABG). However, data are lacking regarding optimal timing and dosing of ASA.

We retrospectively reviewed data from 3018 consecutive patients who underwent CABG surgery between July 2005 and May 2011. Patients were assigned to 3 groups according to the time of the last preoperative ASA dose: (1) 24 hours or less preoperatively (n = 1173), (2) between 24 and 72 hours (n = 876), and (3) more than 72 hours or none (n = 969). In a separate analysis, patients were grouped according to ASA dose: 81 mg (n = 1285), 325 mg (n = 1004), and none (n = 543). The primary outcome was 30-day all-cause mortality.

The 30-day mortality rate was significantly lower in patients who took ASA 24 hours or less preoperatively (1.5%) than in those who took it between 24 and 72 hours (3.2%) or more than 72 hours or none (2.9%). Multivariate analysis showed that ASA within 24 hours preoperatively was associated with reduced mortality (odds ratio [OR], 0.41; 95% confidence interval [CI], 0.20-0.82; P = 0.01). Moreover, mortality was significantly reduced for patients taking 81 mg of ASA (1.4%) compared with 325 mg (2.9%) or none (3.9%). Multivariate analysis demonstrated that 81 mg of ASA decreased mortality risk by 66% (OR, 0.34; 95% CI, 0.18-0.66; P < 0.01), whereas 325 mg of ASA had no mortality benefit (OR, 0.74; 95% CI, 0.41-1.35; P = 0.33) compared with no ASA.

Low-dose ASA use within 24 hours of CABG is independently associated with decreased early postoperative mortality.