Objectives To examine, using cardiac magnetic resonance (CMR), the utility of cardiac biomarkers for the determination of myocyte necrosis and function after coronary artery bypass grafting (CABG), and to test the recently updated guidelines for the diagnosis of postoperative myocardial infarction (type V MI).
Methods and results Forty patients included in a single-centre randomised trial of two surgical techniques for performing CABG underwent serial assessment with CMR biochemical markers. Cine and delayed enhancement CMR (DE-CMR) for assessment of left ventricular (LV) function and irreversible myocyte necrosis was performed and levels of troponin I (TnI) and creatine kinase-MB isoform (CK-MB) were determined. The area under the curve for TnI strongly correlated with the mass of new myocyte necrosis as assessed by DE-CMR (r=0.83, p<0.001), compared with CK-MB (r=0.39, p=0.06). Furthermore, routine assessment of TnI alone at 24 h (>6.6 μg/l) predicted type V MI on DE-CMR with a sensitivity of 88% and specificity of 97%, whereas CK-MB predicted type V MI with a sensitivity of 75% and specificity of 87%.
Conclusions Biomarkers alone (TnI), at an appropriate threshold appear robust for the detection of type V MI, independently of supplementary evidence, as suggested by the ESC/ACCF/AHA/WHF criteria.
- Cardiopulmonary bypass
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Funding This work was supported by a project grant from the British Heart Foundation (grant number PG/05/037), by the Oxfordshire Health Services Research Committee (OHSRC reference G) and by the Oxford Partnership Comprehensive Biomedical Research Centre with funding from the Department of Health's NIHR Biomedical Research Centers funding scheme.
Competing interests HW received research grants from Alexion, Sanofi-Aventis, Eli Lilly, Merck Sharpe & Dohme, The Medicines Company, NIH, Neuren, Glaxo Smith Kline, Pfizer, Roche, Fournier Janssen Cilag, Johnson & Johnson, Proctor & Gamble and Schering Plough. He also received honoraria from Sanofi Aventis and The Medicines Company and consultancy fees from the Medicines Company, Neuren Pharma, Glaxo Smith Kline, Commonwealth Serum Laboratories (CSL) Limited, Bayer and Sanofi Aventis. JBS received honoraria from Pfizer, Boehringer-ingelheim, Siemens and Toshiba Medical Systems. He received consultancy fees from Kai Pharmaceuticals.
Ethics approval This study was conducted with the approval of the local research ethics committee, NRES: 05/Q1603/42.
Provenance and peer review Not commissioned; externally peer reviewed.