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

Background and aim of the study Guidelines on myocardial revascularization indicate for type V myocardial infarction (MI) that postoperative troponin elevations need not be exclusively ischemic but may also be caused by direct epicardial injury. Additional complexity arises from the introduction of high-sensitive troponin markers. The present study attempts to contribute to the understanding of postoperative high-sensitive cardiac troponin T (hs-cTnT) increase. Methods Type of surgery, potential factors affecting the postoperative hs-cTnT increase, and possible thresholds indicative of type V MI were analyzed. Results Among 400 included patients, 2.8% had intervention-related ischemia analogous to the type V MI definition. Receiver-operating characteristics confirmed good discriminatory power for hs-cTnT and creatine kinase myocardial band (CK-MB), with ischemia indicating thresholds for hs-cTnT (1705.5 ng/l) and for CK-MB (113 U/l). The median postoperative hs-cTnT/CK-MB increase differed significantly depending on the type of surgery, with the highest increase after mitral valve and the lowest after off-pump coronary surgery. Regression analysis confirmed Maze procedure (p<0.001), cardiopulmonary bypass time (p=0.03), emergency indications (p= 0.01) and blood transfusion (p=0.02) as significant factors associated with hs-cTnT increase. In contrast, CK-MB increase was also associated with mortality (p=0.002). Intra-pericardial defibrillation was the only ischemia-independent factor additionally associated with proposed thresholds (p<0.001). Conclusions The present results confirm the influence of the type of surgery and other intervention-related parameters on the postoperative hs-cTnT increase. Type V MI-indicating thresholds may require reassessment, especially using high-sensitive markers.