Diagnostic accuracy of baseline troponin and troponin change for the diagnosis of myocardial infarction complicated with heart failure.

Background: The diagnosis of myocardial infarction (MI) in the presence of heart failure (HF) presents a clinical problem. While diagnostic algorithms using high-sensitivity cardiac troponin have been established for suspected MI, their accuracy in patients with HF remains uncertain. This study aims to assess the diagnostic accuracy of high-sensitivity troponin I (TnI) levels in identifying acute MI among patients with HF, focusing on baseline, absolute and relative TnI changes.

Methods: Data from 562 individuals admitted to the emergency department with suspected MI were retrospectively analysed. Two-point TnI and baseline brain natriuretic peptide (BNP) test results were available. HF status was determined based on clinical, laboratory and instrumental criteria.

Results: Among the 562 patients, 299 (53.2%) were confirmed having MI. Baseline TnI demonstrated predictive capability for MI in the overall population (area under the curve (AUC) 0.63), while TnI relative change exhibited superior performance (AUC 0.83). Baseline TnI accuracy varied significantly by group, notably decreasing in the third group (severe HF) (AUC 0.54) compared with the first and second groups (AUC 0.67 and AUC 0.71, respectively). TnI relative change demonstrated consistent accuracy across all groups, with AUCs of 0.79, 0.79 and 0.89 for the first, second and third groups, respectively, even after adjustment for age, sex and glomerular filtration rate.

Discussion: Troponin relative change is a reliable predictor of MI, even in patients with acute HF. Baseline TnI accuracy is influenced by HF severity. It is essential to consider HF status and BNP levels when employing high-sensitivity cardiac troponin testing to rule out suspected MIs.