Cardiac Troponin T and Troponin I in the General Population: Comparing and Contrasting their Genetic Determinants and Associations with Outcomes.
Welsh P., Preiss D., Hayward C., Shah ASV., McAllister D., Briggs A., Boachie C., McConnachie A., Padmanabhan S., Welsh C., Woodward M., Campbell A., Porteous D., Mills NL., Sattar N.
BACKGROUND: There is great interest in widening the use of high sensitivity cardiac troponins for population cardiovascular disease (CVD) and heart failure screening. However, it is not clear whether cardiac troponin T (cTnT) and troponin I (cTnI) are equivalent measures of risk in this setting. We aimed to compare and contrast i) the association of cTnT and cTnI with CVD and non-CVD outcomes, and ii) their determinants in a Genome wide association study (GWAS). METHODS: High-sensitivity cTnT and cTnI were measured in serum from 19,501 individuals in Generation Scotland Scottish Family Health Study. Median follow-up was 7.8 years (Q1-Q3 7.1-9.2). Associations of each troponin with a composite CVD outcome (1,177 events), CVD death (n=266), non-CVD death (n=374), and heart failure (n=216) were determined using Cox models. A genome-wide association study was conducted using a standard approach developed for the cohort. RESULTS: Both cTnI and cTnT were strongly associated with CVD risk in unadjusted models. After adjusting for classical risk factors, the hazard ratio for a one standard deviation increase in log transformed troponin was 1.24 (95%CI 1.17-1.32) and 1.11 (1.04-1.19) for cTnI and cTnT, respectively; ratio of HRs 1.12 (1.04-1.21). cTnI, but not cTnT, was associated with MI and CHD. Both cTnI and cTnT had strong associations with CVD death and heart failure. By contrast, cTnT, but not cTnI, was associated with non-CVD death; ratio of HRs 0.77 (0.67-0.88). We identified five loci (53 individual SNPs) that had GWAS significant associations with cTnI, and a different set of four loci (4 SNPs) for cTnT. CONCLUSIONS: The upstream genetic causes of low grade elevations in cTnI and cTnT appear distinct, and their associations with outcomes also differ. Elevations in cTnI are more strongly associated with some CVD outcomes, whereas cTnT is more strongly associated with the risk of non-CVD death. These findings help inform selection of an optimal troponin assay for future clinical care and research in this setting.