Trajectory of macrotroponin in a community cohort.

BACKGROUND: Cardiac troponin I (cTnI) is a biomarker for myocardial injury. However, macrotroponin, a complex of cTnI and endogenous cardiac troponin autoantibodies, may artefactually elevate cTnI levels with potential to mislead clinicians, leading to inappropriate investigation and management. AIM: To examine the prevalence and trajectory of macrotroponin in participants of the prospective community-based SCreening Evaluation of the Evolution of New Heart Failure (SCREEN-HF) study cohort. METHODS: Inclusion criteria were age ≥ 60 years with one or more self-reported ischaemic or other heart diseases, irregular or rapid heart rhythm, cerebrovascular disease, renal impairment or treatment for hypertension or diabetes for ≥2 years. Exclusion criteria were known heart failure or cardiac abnormality on echocardiography or other imaging. A cutoff residual cTnI activity ≤20% after polyethylene glycol precipitation was used to detect macrotroponin in plasma samples with cTnI levels above the sex-specific 99th percentile reference limits. RESULTS: Of 3156 SCREEN-HF participants with one or more cTnI measurements, 64 (2%) had macrotroponin. Among 2243 participants with two or more cTnI measurements, cTnI levels with macrotroponin were dynamic, although most elevated cTnI levels with macrotroponin at baseline remained elevated (14 of 16 men, 9 of 11 women) for several years during follow-up. CONCLUSIONS: Elevated cTnI levels with macrotroponin remained elevated for several years in asymptomatic individuals in this community-based cohort. While interpreting elevated cTnI levels in the clinical context, recording macrotroponin as a diagnosis could alert clinicians to possible artefactual elevation of cTnI levels during subsequent clinical presentation and avoid inappropriate investigation and management.