Troponin I and T Show Distinct Kinetics After Coronary Bypass Surgery: Implications for Type 5 MI Diagnosis
This meta-analysis of 32 studies reveals that post-CABG high-sensitivity troponin I peaks nearly threefold higher than troponin T relative to their respective 99th percentiles, with further divergence in off-pump versus on-pump surgery. Current MI-5 diagnostic thresholds do not differentiate between isoforms, meaning assay choice directly impacts diagnosis. The findings mandate assay-specific and isoform-specific cutoffs for perioperative MI detection.
The original study
High-Sensitivity Cardiac Troponin I and T Kinetics Differ following Coronary Bypass Surgery: A Systematic Review and Meta-Analysis.
- Authors
- Denessen EJ, Heuts S, Daemen JH, van Doorn WP, Vroemen WH, Sels JW, et al.
- Journal
- Clinical chemistry
- Type
- Meta-Analysis, Systematic Review, Journal Article, Research Support, Non-U.S. Gov't
- PMID
- 36366960
Original abstract
BACKGROUND: Cardiac troponin I and T are both used for diagnosing myocardial infarction (MI) after coronary artery bypass grafting (CABG), also known as type 5 MI (MI-5). Different MI-5 definitions have been formulated, using multiples of the 99th percentile upper reference limit (10×, 35×, or 70× URL), with or without supporting evidence. These definitions are arbitrarily chosen based on conventional assays and do not differentiate between troponin I and T. We therefore investigated the kinetics of high-sensitivity cardiac troponin I (hs-cTnI) and T (hs-cTnT) following CABG. METHODS: A systematic search was applied to MEDLINE and EMBASE databases including the search terms "coronary artery bypass grafting" AND "high-sensitivity cardiac troponin." Studies reporting hs-cTnI or hs-cTnT on at least 2 different time points were included. Troponin concentrations were extracted and normalized to the assay-specific URL. RESULTS: For hs-cTnI and hs-cTnT, 17 (n = 1661 patients) and 15 studies (n = 2646 patients) were included, respectively. Preoperative hs-cTnI was 6.1× URL (95% confidence intervals: 4.9-7.2) and hs-cTnT 1.2× URL (0.9-1.4). Mean peak was reached 6-8 h postoperatively (126× URL, 99-153 and 45× URL, 29-61, respectively). Subanalysis of hs-cTnI illustrated assay-specific peak heights and kinetics, while subanalysis of surgical strategies revealed 3-fold higher hs-cTnI than hs-cTnT for on-pump CABG and 5-fold for off-pump CABG. CONCLUSION: Postoperative hs-cTnI and hs-cTnT following CABG surpass most current diagnostic cutoff values. hs-cTnI was almost 3-fold higher than hs-cTnT, and appeared to be highly dependent on the assay used and surgical strategy. There is a need for assay-specific hs-cTnI and hs-cTnT cutoff values for accurate, timely identification of MI-5.