Postoperative myocardial infarction remains a serious complication in cardiac surgery. The incidence and impact of this condition in acute type A aortic dissection are poorly understood.A total of 1445 patients with acute type A aortic dissection who underwent surgery were enrolled in the International Registry of Acute Aortic Dissection from 1996 to 2013. Individuals with preoperative myocardial infarction at hospital presentation and a history of myocardial infarction were excluded. Patients with postoperative myocardial infarction (n = 38, 2.6%) were compared with those without postoperative myocardial infarction (n = 1407, 97.4%).The postoperative myocardial infarction group was more often of white race (100% vs 90%, P = .043) with bicuspid aortic valve (15.6% vs 4.5%, P = .015). Imaging demonstrated more aortic root involvement (75.8% vs 49.5%, P = .003), pericardial effusion (65.5% vs 44.1%, P = .022), and coronary artery compromise (27.3% vs 10.2%, P = .022). Patients with postoperative myocardial infarction were more frequently hypotensive or in shock during surgery (42.9% vs 25.5%, P = .021). Patients with postoperative myocardial infarction were more likely to have undergone root replacement (54.5% vs 33.3%, P = .011), coronary artery bypass grafting (28.6% vs 7.4%, P < .001), or aortic valve replacement (40.0% vs 23.8%, P = .027), and less likely to have had complete arch replacement (2.8% vs 14.0%, P = .050). Median circulatory arrest time was higher in postoperative myocardial infarction (60 vs 38 minutes, P = .024). In-hospital mortality (57.9% vs 16.3%, P < .001) and Kaplan–Meier estimates of 5-year mortality (P = .007) were distinctly higher in postoperative myocardial infarction.Postoperative myocardial infarction is a devastating complication of type A aortic dissection repair. It is associated with bicuspid aortic valve, root involvement, pericardial effusion, and extent of surgical repair. Patients with postoperative myocardial infarction have higher serious postoperative complications, in-hospital mortality, and 5-year mortality rates than those without postoperative myocardial infarction.