Background: Determinants of cardiomyocyte injury as quantified by high-sensitivity cardiac troponin I (cTnI) in young and healthy individuals, and sex-specific 99th percentiles are largely unknown.
Methods: Our study included 2077 adults from the general population aged 25-41 years without cardiovascular disease. cTnI was measured using a high-sensitivity assay. We performed stepwise backward linear regression analyses to identify variables independently associated with hs-cTnI levels, and calculated narrow-sense heritability from 1638-genotyped participants.
Results: Median age was 37 years. cTnI was quantifiable in all but 11 participants (99.5 %). Median (interquartile range) cTnI was significantly higher in men than in women [0.99 (0.71; 1.65) versus 0.47 (0.33; 0.71) ng/L, p < 0.0001]. The 99th percentile of cTnI was 15.79 ng/L in men and 5.11 ng/L in women. Out of 46 variables, 22 independent determinants for cTnI were identified. The strongest associations were observed with sex, age, systolic blood pressure, heart rate, left ventricular mass, N-terminal pro B-type natriuretic peptide, and creatine kinase (all p < 0.0001). The final model explained 36 % of the overall cTnI variability. Heritability of cTnI was estimated to be 29 % (p = 0.005), but became non-significant when the residuals of the multivariable model were used for analysis (5 %, p = 0.36).
Conclusions: Sex, age, and systolic blood pressure belong to the strongest determinants of hs-cTnI in healthy adults. The 99th percentile was three times higher in men compared to women. Hence, sex-specific cut-off values may be preferable when applying hs-cTnI for screening purposes. Our results may also improve the interpretation of cTn levels in daily clinical practice.
Keywords: Age; B-type natriuretic peptide; Blood pressure; Epidemiology; Heritability; Hypertrophy; Sex; Troponin.