The prevention of perioperative atrial fibrillation has the potential to reduce mortality, stroke, and hospital stays in patients undergoing thoracic surgery. Data from cardiac surgery patients suggest that prevention of perioperative atrial fibrillation using an anti-inflammatory agent, such as colchicine, is feasible. The COP-AF trial will assess whether the administration of oral colchicine will reduce the incidence of perioperative atrial fibrillation in patients undergoing major thoracic surgery.