Epidemiology, clinical outcomes and risk factors for mortality and severe postoperative complications in cardiac surgery patients admitted to intensive care units in Brazil: a multicentre observational study

Abstract Background Cardiac surgery carries substantial risks of perioperative complications and mortality; however, outcome data from low- and middle-income countries are scarce. This prospective observational cohort study conducted across 11 Brazilian hospitals aimed to determine the incidence of early mortality and major postoperative complications in patients undergoing cardiac surgery in Brazil. Methods Adults (≥18 yr) undergoing coronary, valvular, or percutaneous cardiac surgery requiring postoperative ICU admission, excluding patients under exclusive palliative care, device implantation only, or moribund before surgery. Risk factors and incidence of mortality or severe postoperative complications within the first 3 postoperative days or until ICU discharge (whichever occurs first). Risk factors were assessed using generalised linear mixed-effects models, reported as odds ratios with 95% confidence intervals. Results Between September 2023 and March 2025, 528 patients were enrolled. Among 528 patients (91% open-heart, mainly coronary artery bypass grafting and valve replacements), 170 (32%) experienced early mortality or severe postoperative complications, most within the first 24 h. The most frequent complications were severe haemodynamic instability (126, 24%), and acute respiratory distress syndrome (71, 13%). Most events occurred on the day of ICU admission (132 of 170, 78%). Risk factors of the primary outcome were prior stroke (3.22 [1.02–10.17], P=0.046), preoperative thrombocytopenia (2.83 [1.46–5.48], P=0.002), open-heart surgery (6.34 [1.66–24.21], P=0.007), biological valves (3.94 [1.18–11.31] P=0.026). Early postoperative markers of clinical deterioration were higher Sequential Organ Failure Assessment score on day 0 (1.35 [1.19–1.53], P<0.001), lower arterial pH on day 0 (0.53 [0.34–0.83], P=0.006), and vasoplegia (15.35 [6.05–38.94], P<0.001). Conclusions In this multicentre cohort of cardiac surgery patients in Brazil, one in three experienced early mortality or severe postoperative complications, mostly within the first 24 h. Identified predictors of early postoperative deterioration may help guide perioperative strategies and underscore the need for developing prognostic models adapted to local contexts. Clinical trial registration NCT06154473.