IntroductionPostoperative myocardial injury after noncardiac surgery is common and is associated with short- and long-term morbidity and mortality. However, the incidence and risk factors for postoperative acute myocardial injury (POAMI) are currently unknown due to inconsistent definitions.MethodsWe systematically searched PubMed and Web of Science to identify studies that applied the change value of preoperative and postoperative cardiac troponins to define cardiac injury. We estimated the pooled incidence, risk factors, and 30-day and long-term mortality of POAMI in noncardiac patients. The study protocol was registered with PROSPERO, CRD42023401607.ResultsTen cohorts containing 11,494 patients were included for analysis. The pooled incidence of POAMI was 20% (95% CI: 16% to 23%). Preoperative hypertension (OR: 1.47; 95% CI: 1.30 to 1.66), cardiac failure (OR: 2.63; 95% CI: 2.01 to 3.44), renal impairment (OR: 1.66; 95% CI: 1.48 to 1.86), diabetes (OR: 1.43; 95% CI: 1.27 to 1.61), and preoperative beta-blocker intake (OR: 1.65; 95% CI: 1.10 to 2.49) were the risk factors for POAMI. Age (mean difference: 2.08 years; 95% CI: -0.47 to 4.62), sex (male, OR: 1.16; 95% CI: 0.77 to 1.76), body mass index (mean difference: 0.35; 95% CI: -0.86 to 1.57), preoperative coronary artery disease (OR: 2.10; 95% CI: 0.85 to 5.21), stroke (OR: 0.90; 95% CI: 0.50 to 1.59) and preoperative statins intake (OR: 0.65; 95% CI: 0.21 to 2.02) were not associated with POAMI. Patients with POAMI had higher preoperative hsTnT levels (mean difference: 5.92 ng/L; 95% CI: 4.17 to 7.67) and lower preoperative hemoglobin levels (mean difference: -1.29 g/dL; 95% CI: -1.43 to -1.15) than patients without.ConclusionBased on this meta-analysis, approximately 1 in 5 of noncardiac patients develop POAMI. However, the lack of a universally recognized definition for POAMI, which incorporates diverse cardiac biomarkers and patient groups, poses a challenge in accurately characterizing its incidence, risk factors, and clinical outcomes.