Association of Postoperative Cardiac Troponin Elevation with Clinical Outcomes after Coronary Artery Bypass Grafting: A Systematic Review and Meta-Analysis

Introduction Postoperative cardiac troponin elevation is common after coronary artery bypass grafting (CABG), but interpretation is complicated by procedural myocardial injury, assay heterogeneity, variable sampling, and inconsistent thresholds. We evaluated its association with outcomes, kinetics, diagnostic thresholds, and applications. Methods MEDLINE, Embase, Web of Science, and CENTRAL were searched from inception to 1 August 2026, supplemented by citation searching. Adult CABG studies reporting postoperative cardiac troponin I or T were eligible. Duplicate reports and overlapping cohorts were mapped. Adjusted hazard ratios and odds ratios were pooled separately using restricted maximum-likelihood random-effects models with modified Hartung-Knapp confidence intervals. Composite outcomes were analysed exploratorily, with sensitivity analyses excluding extreme or less CABG-specific estimates. Results Sixty-four reports were included; 43 contained quantitative findings, although only 15 independent studies contributed to one or more meta-analyses, while 21 reports contributed primarily narrative evidence. Four independent cohorts comprising 23,282 participants showed an association between greater postoperative troponin elevation and long-term all-cause mortality (hazard ratio 2.00, 95% confidence interval 1.11–3.60; I 2 =53.9%; prediction interval 0.50–7.95). Eight cohorts comprising 8,438 participants contributed to an exploratory analysis of short-term adverse outcomes (odds ratio 8.21, 95% confidence interval 2.62–25.71; I 2 =80.6%). A stricter five-cohort sensitivity analysis remained positive (odds ratio 5.34, 95% confidence interval 1.90–15.05), although heterogeneity remained substantial. Evidence for cardiovascular events and postoperative atrial fibrillation was sparse and imprecise. The most informative measurement occurred within 24 h. Certainty was low for long-term mortality and very low for the other pooled outcomes. Conclusion Greater postoperative troponin elevation after CABG is associated with long-term mortality and short-term adverse outcomes, but heterogeneity prevents recommendation of a universal threshold. Interpretation should integrate troponin trajectory, assay, operative context, electrocardiography, imaging, and haemodynamic findings.