Emilie P Belley-Cote 1 , 2 , 3 , André Lamy 3 , 4 , P J Devereaux 1 , 2 , 3 , Peter Kavsak 5 , François Lamontagne 6 , Deborah J Cook 1 , 2 , Kevin Kennedy 1 , Jessica Vincent 3 , Yongning Ou 3 , George Tagarakis 7 , Richard P Whitlock 1 , 3 , 4
10 June 2019
Using data from the CORONARY trial ( n = 4752), we evaluated the incidence and prognostic significance of myocardial infarction (MI) applying different definitions based on peak postoperative creatine kinase-MB isoenzyme and cardiac troponin levels. We then aimed to identify the peak cardiac troponin during the first 3 postoperative days that was independently associated with a 2-fold increase in 30-day mortality.
To combine different assays, we analysed cardiac troponins in multiples of their respective upper limit of normal (ULN). We identified the lowest threshold with a hazard ratio (HR) >2 for 30-day mortality independent of EuroSCORE and on- versus off-pump surgery.
Depending on the definition used based on creatine kinase-MB, the incidence of MI after coronary artery bypass grafting (CABG) ranged from 0.6% to 19% and the associated HRs for 30-day mortality ranged from 2.7 to 6.9. Using cardiac troponin (1528 patients), the incidence of MI ranged from 1.7% to 13% depending on the definition used with HRs for 30-day mortality ranging from 5.1 to 7.2. The first cardiac troponin threshold we evaluated, 180xULN, was associated with an adjusted HR for 30-day mortality of 7.6 [95% confidence interval (CI) 3.4–17.1] when compared to <130xULN. The next independent threshold was 130xULN with an adjusted HR for 30-day mortality of 7.8 (95% CI 2.3–26.1). The next cardiac troponin tested threshold (70xULN) did not meet criteria for significance.