Clinical Chemistry - Journal Club
The Clinical Chemistry Journal Club allows readers to discuss key articles by using focused slides as teaching tools. Each month Clinical Chemistry posts the original article and slides online, and they are then distributed to individuals and university Journal Clubs.
Original Article: https://doi.org/10.1093/clinchem/hvag012
Slides: Download ppt
The definition of periprocedural myocardial infarction (PMI) after coronary artery bypass grafting (CABG) remains debated, particularly regarding the use of cardiac troponins vs creatine kinase MB isoform (CK-MB), and biomarker thresholds seem outdated [10×, 35×, or 70× multiples of upper reference limits (URL)]. We studied high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI), and CK-MB, following CABG patients with an emphasis on those with an uncomplicated course.
Patients undergoing isolated on-pump CABG and minimally invasive direct CABG (MIDCAB) were prospectively included. Blood was collected preoperatively and then postoperatively at intensive care unit (ICU) arrival, 5 h and 8 h subsequently, and postoperative days 1 and 3. hs-cTnT (Roche), hs-cTnI (Abbott), and CK-MB (Roche) were measured and normalized using URLs according to package inserts or the Universal Sample Bank.
Sixty-one on-pump CABG and 22 MIDCAB patients were included. On-pump CABG patients showed a median (interquartile range) hs-cTnT peak of 610 (466–879) ng/L, hs-cTnI 3918 (2154–6713) ng/L, and CK-MB 22.0 (14.9–34.8) µg/L 5 h after ICU arrival. When normalized according to package inserts, this corresponds to 44× (33×–63×) URL, 150× (82×–256×) URL, 4.5 × (3.0×–7.1×) URL, respectively. These values slightly differ when sex-specific or other URL definitions are used (P > 0.05). In subgroup analyses, MIDCAB patients had reduced biomarker concentrations, and significant differences were observed between cardioplegia regimens (P < 0.001).
The postoperative kinetics of hs-cTnT, hs-cTnI, and CK-MB in CABG patients with an uncomplicated course illustrate that hs-cTn, in particular, surpasses current diagnostic cutoffs for PMI. This varies in time, across hs-cTn assays, surgical approaches, and cardioplegia regimens.