Does Preoperative Troponin Level Impact Outcomes After Coronary Artery Bypass Grafting?

BACKGROUND: As a marker of myocardial injury, troponin level correlates with adverse outcomes after myocardial infarction (MI). We hypothesized that patients with a higher preoperative troponin level would have increased morbidity and mortality after coronary artery bypass grafting (CABG).
METHODS: Preoperative troponin measurements were available for 1,272 patients who underwent urgent or emergent isolated CABG at our institution from 2002 to 2016. Logistic regression assessed the risk-adjusted effect of peak troponin level on morbidity and mortality. Long-term survival analysis was performed with Kaplan-Meier and Cox proportional hazards models.
RESULTS: Preoperative troponin was positive in 835 patients (65.6%). The median peak troponin for this group was 3.2 ng/mL (interquartile range, 0.6 to 11.9 ng/mL), with a median time from peak troponin to the operation of 3 days (interquartile range, 1 to 4 days). Positive troponin was associated with more significant comorbid conditions and more extensive coronary artery disease. Operative mortality (3.7% versus 1.1%, p = 0.009), major morbidity (11.7% versus 3.9%, p < 0.001), and long-term mortality (median survival 12.5 years versus 13.6 years, p = 0.01) were increased in the positive troponin group. After risk adjustment, positive troponin was not independently associated with increased operative mortality (odds ratio, 2.61; p = 0.053). Adjusted and unadjusted analysis showed the peak preoperative troponin level did not independently predict death at any time point (all odds ratios, 1.0; p > 0.05).
CONCLUSIONS: A positive preoperative troponin correlates with worse outcomes after CABG, but risk adjustment eliminates much of the short-term predictive value of this biomarker. Peak troponin level does not influence outcomes after CABG and is a poor predictor of events when The Society of Thoracic Surgeons predictive models are used.