False-positive cardiac troponin I values in healthy athletes post COVID-19 Infection: concerning insights from a prospective cohort study

Abstract Background Cardiac troponin I and T (cTnI, cTnT) are cardiac-specific biomarkers that detect and quantify cardiomyocyte injury. In patients with symptoms possibly indicating acute myocardial infarction (AMI), detection of elevated cTnT or cTnI concentrations usually mandates invasive coronary angiography. Accordingly, false-positive cTnT or cTnI concentrations could have detrimental consequences. Unfortunately, little is known about the prevalence and triggers of false-positive cTnI concentrations. Based on two index cases seen by one of us, we hypothesized that false-positive cTnI values may be common after COVID-19 infection and that macrotroponin, a complex formed between endogenous cTn autoantibodies and circulating cTn, may be the underlying cause. Purpose We aimed to test these hypotheses in a prospective cohort study. Methods We prospectively investigated professional athletes coming to the mandatory return to sports investigation at least 10 days after COVID-19 infection between 2022 and 2023 in an observational study. The presence of false-positive cTnI was centrally adjudicated in individuals that had elevated cTnI concentrations with one (or two) high-sensitivity cTnI assays, but normal high-sensitivity cardiac troponin T concentrations and normal electrocardiography (ECG), normal echocardiography, and normal cardiac magnetic resonance imaging (CMR). Divergences in hs-cTn concentrations were investigated using sex-specific upper limits of normal (ULN) of 4 different assays (hs-cTnI: Alinity/Abbott Diagnostic, hs-cTnI: Atellica/Siemens Healthineers, hs-cTnI: Access Beckman Coulter; hs-cTnT: Cobas/Roche Diagnostics). Athletes were instructed to cease training 48 hours before blood testing. Athletes with divergent hs-cTn assay results underwent further analysis for macrotroponin using sucrose gradient ultracentrifugation. Results Among 35 enrolled athletes (median age 24 years, 19 women and 16 men), 18 athletes had normal hs-cTn concentrations with all four hs-cTnT/I assays. In 17 athletes (48.6%), hs-cTn concentration was increased in at least one assay above the ULN, mostly one hs-cTnI method (hs-cTnI, Alinity) with normal concentrations of the other assays and normal cardiac imaging results. In contrast, two athletes had elevations in all hs-cTnI/T assays. Sucrose gradient ultracentrifugation provided evidence of macrotroponin in 15 of the 17 athletes (88%). Conclusions False-positive cTnI values are common after COVID-19 infection and should be considered in the differential diagnosis. Assay interference by macrotroponin seems to be the underlying mechanisms in most individuals. Documentation of normal hs-cTnT concentrations helps in the early detection of false-positive cTnI values.