Preoperative Troponin Levels and Outcomes of Coronary Surgery Following Myocardial Infarction

Background: This study evaluates the impact of peak preoperative troponin level on outcomes of coronary artery bypass grafting (CABG) for non-ST-elevation myocardial infarction (NSTEMI). Methods: This was a retrospective review of patients undergoing isolated CABG from 2011-2018 with presentation of NSTEMI. Patients were stratified into low- and high-risk groups based on median preoperative peak troponin (1.95ng/dL). Major cardiac and cerebrovascular events (MACCE) and mortality were compared. Multivariable analysis was performed to model risk factors for MACCE and mortality. Results: This study included 1,211 patients, 607 low- (≤1.95ng/dL) and 604 high-risk (>1.95ng/dL). Patients were well-matched with respect to age and comorbidity. High-risk patients had lower median preoperative ejection fraction (46.5% [IQR 35.0%-55.0%] vs 53.0% [IQR 40.0%-58.0%]) and higher incidence of preoperative intra-aortic balloon pump (15.9% vs 8.73%). Intensive care unit (47 hours [IQR 26-82] vs 43 hours [IQR 25-69]) and hospital lengths of stay (10 days [IQR 8-13] vs 9 days [IQR 8-12]) were longer in the high-risk group (each P<0.05). Postoperative complications and thirty-day, one- and five-year rates of both MACCE and survival were similar between groups. Peak troponin >1.95ng/dL was not associated with increased hazards for MACCE, mortality, or readmission in multivariable modeling. In sub-analyses, neither increasing troponin as a continuous variable nor peak troponin >10.00ng/mL were associated with increased hazards for these outcomes. Conclusions: Higher preoperative troponin levels are associated with longer lengths of stay but not MACCE or mortality following CABG. Dictating timing of CABG for NSTEMI based on peak troponin does not appear to be warranted.