Usefulness of postoperative high‐sensitive troponin T measurement and implications for defining type 5 infarction

BACKGROUND AND AIM OF THE STUDY: Guidelines indicate for type 5 myocardial infarction (MI) that postoperative troponin need not be exclusively ischemic but may also be caused by epicardial injury. Complexity arises from the introduction of high‐sensitive troponin. This study attempts to contribute to the understanding of postoperative high‐sensitive cardiac troponin T (hs‐cTnT) increase. METHODS: The median enzyme increase of different cardiac operations was compared. Linear regression analyses were used to determine correlations between enzyme rise and independent parameters. Receiver‐operating characteristics (ROC) served to evaluate the discriminatory power of enzyme rise in detecting ischemia and to determine possible thresholds. RESULTS: Among 400 patients, 2.8% had intervention‐related ischemia analogous to type 5 MI definition. The median postoperative hs‐cTnT/creatine kinase myocardial band (CK‐MB) increase varied according to types of surgery, with highest increase after mitral valve and lowest after off‐pump coronary surgery. After ruling out patients with preoperatively elevated hs‐cTnT, regression analysis confirmed Maze procedure (p < .001), intra‐pericardial defibrillation (p = .002), emergency intervention (p = .01), blood transfusions (p = .02), and cardiopulmonary bypass time (p = .03) as significant factors associated with hs‐cTnT increase. In addition, CK‐MB increase was associated with mortality (p = .002). ROC confirmed good discriminatory power for hs‐cTnT and CK‐MB with ischemia‐indicating thresholds of 1705.5 ng/L (hs‐cTnT) and 113 U/L (CK‐MB) considering different types of operations. CONCLUSIONS: The Influence of the type of surgery and intervention‐related parameters on hs‐cTnT increase was confirmed. Potential thresholds indicating perioperative ischemia appear to be significantly elevated for high sensitive markers.