MD; for the COPPS-2 Investigators IMPORTANCE Postpericardiotomy syndrome, postoperative atrial fibrillation (AF), and postoperative effusions may be responsible for increased morbidity and health care costs after cardiac surgery. Postoperative use of colchicine prevented these complications in a single trial.OBJECTIVE To determine the efficacy and safety of perioperative use of oral colchicine in reducing postpericardiotomy syndrome, postoperative AF, and postoperative pericardial or pleural effusions. DESIGN, SETTING, AND PARTICIPANTSInvestigator-initiated, double-blind, placebo-controlled, randomized clinical trial among 360 consecutive candidates for cardiac surgery enrolled in 11 Italian centers between March 2012 and March 2014. At enrollment, mean age of the trial participants was 67.5 years (SD, 10.6 years), 69% were men, and 36% had planned valvular surgery. Main exclusion criteria were absence of sinus rhythm at enrollment, cardiac transplantation, and contraindications to colchicine. INTERVENTIONSPatients were randomized to receive placebo (n=180) or colchicine (0.5 mg twice daily in patients Ն70 kg or 0.5 mg once daily in patients <70 kg; n=180) starting between 48 and 72 hours before surgery and continued for 1 month after surgery. MAIN OUTCOMES AND MEASURESOccurrence of postpericardiotomy syndrome within 3 months; main secondary study end points were postoperative AF and pericardial or pleural effusion. RESULTSThe primary end point of postpericardiotomy syndrome occurred in 35 patients (19.4%) assigned to colchicine and in 53 (29.4%) assigned to placebo (absolute difference, 10.0%; 95% CI, 1.1%-18.7%; number needed to treat = 10). There were no significant differences between the colchicine and placebo groups for the secondary end points of postoperative AF (colchicine, 61 patients [33.9%] CONCLUSIONS AND RELEVANCE Among patients undergoing cardiac surgery, perioperative use of colchicine compared with placebo reduced the incidence of postpericardiotomy syndrome but not of postoperative AF or postoperative pericardial/pleural effusion. The increased risk of gastrointestinal adverse effects reduced the potential benefits of colchicine in this setting.