Cardiac Myosin‐Binding Protein C for Diagnosis of Myocardial Infarction in Patients With Prior Coronary Artery Bypass Grafting

Background Diagnosing myocardial infarction in patients with prior coronary artery bypass grafting (CABG) remains challenging, primarily because of lower diagnostic accuracy of high‐sensitivity cardiac troponin (hs‐cTn). cMyC (cardiac myosin‐binding protein C), because of its faster release kinetics and greater abundance, may offer improved diagnostic performance in this population. Methods The diagnostic accuracy of cMyC was directly compared with that of hs‐cTnT and hs‐cTnI in a prospective, international, multicenter, diagnostic study enrolling adult patients presenting to the emergency department with acute chest discomfort. Final diagnoses were centrally adjudicated by 2 independent cardiologists using all available clinical and study‐specific data, including imaging and serial hs‐cTnT measurements. Patients were stratified according to the presence or absence of prior CABG. Results Among 4752 patients, 387 (8%) had prior CABG (median age, 75 years; 86% men). The incidence of myocardial infarction was significantly higher in patients with prior CABG (38% versus 16%; P <0.001). In the CABG group, the diagnostic accuracy of cMyC as quantified by the area under the curve was 0.88 (95% CI, 0.85–0.92), which was comparable but not superior to that of hs‐cTnT (0.89 [95% CI, 0.86–0.92]) and hs‐cTnI (0.88 [95% CI, 0.84–0.91]). These findings were consistent across alternative high‐sensitivity cMyC assays. Conclusions In patients with prior CABG, cMyC demonstrated high diagnostic accuracy for myocardial infarction, but not superior to established hs‐cTnT and hs‐cTnI assays. Registration URL: clinicaltrials.gov ; Unique Identifier: NCT00470587.