AIM: Gastrointestinal (GI) complications following cardiac surgery are infrequent, but associated with high rates of postoperative mortality. The aim of our study was to identify risk factors predisposing patients to GI complications following cardiac surgery and describe the outcomes of patients suffering a GI complication. METHODS: This was a retrospective cohort study of 6769 consecutive patients undergoing cardiac surgeries (at least one of coronary artery bypass grafting (CABG), aortic valve replacement, mitral valve replacement, or surgery on thoracic aorta) at a single Scottish centre between 1 January 2015 and 27 September 2023. Cohort demographics, intra-operative details and postoperative outcomes were compared between patients who did and who did not experience a gastrointestinal GI complication. RESULTS: Patients who experienced a GI complication had greater rates of thirty-day mortality (14.4% vs 2.4%, p <
0.001) and in-hospital mortality (6.8% vs 1.1%, p <
0.001) compared with those who did not. We identified previous percutaneous coronary intervention (PCI) (Odds ratio (OR) 2.27 [1.24-4.17], p = 0.007) and combined cardiac surgery (OR 1.67 [1.02-2.74], p = 0.043) as two risk factors for developing a GI complication, in addition to several previously identified risk factors (postoperative atrial fibrillation, postoperative vascular complication, use of pre-operative inotropes and increased age). CONCLUSIONS: GI complications frequently occur in elderly, co-morbid patients and in conjunction with other complications. Particularly lethal are mesenteric ischemia, GI bleeding, and small bowel obstruction. Extra caution should be observed in the patient group undergoing more than one cardiac procedure or those with a prior history of coronary artery disease. Prompt emergency laparotomy is a potentially life-saving intervention in promptly diagnosed patients, but confers a high risk of intra-operative and thirty-day mortality.