Cardiac Troponin T and Troponin I in the General Population

Abstract

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 (1) the association of cTnT and cTnI with CVD and non-CVD outcomes, and (2) their determinants in a genome-wide association study.

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 (quartile 1 to quartile 3, 7.1-9.2). Associations of each troponin with a composite CVD outcome (1177 events), CVD death (n=266), non-CVD death (n=374), and heart failure (n=216) were determined by 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 1 SD 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 hazard ratios 1.12 (1.04-1.21). cTnI, but not cTnT, was associated with myocardial infarction and coronary heart disease. 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 hazard ratios 0.77 (0.67-0.88). We identified 5 loci (53 individual single-nucleotide polymorphisms) that had genome-wide significant associations with cTnI, and a different set of 4 loci (4 single-nucleotide polymorphisms) 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 the selection of an optimal troponin assay for future clinical care and research in this setting.

Keywords: cardiovascular diseases; genetics; risk factors; troponin; troponin T.

Figure 1.

Association of cTnI and cTnT unadjusted and adjusted (as per Table 2) with the composite CVD event. The referent (HR=1) is undetectable levels of cTnI and cTnT, respectively. Both splines on log scale. cTnI indicates high-sensitivity cardiac troponin I; cTnT, high-sensitivity cardiac troponin T; CVD, cardiovascular disease; and HR, hazard ratio.

Figure 2.

Rates of CVD per 1000 person-years (n=1177 events) by low/intermediate/high groupings of both cTnI and cTnT. For cTnI: low ≤1.8ng/L (n=9426), intermediate 1.9 to 3.0 ng/L (n=5052), and high ≥3.1 ng/L (n=5023). For cTnT: low ≤3.0 ng/L (n=9106), intermediate 3.0 to 5.7 ng/L (n=5200), and high ≥5.8 ng/L (n=5195). cTnI indicates high-sensitivity cardiac troponin I; cTnT, high-sensitivity cardiac troponin T; and CVD, cardiovascular disease.

Figure 3.

Manhattan plots for single-nucleotide polymorphisms associated with cTnI and cTnT after adjustment for age and sex (n=19 130). A, cTnI. B, cTnT. The horizontal black dotted line indicates genome-wide significance at P<5×10–8, and the horizontal gray dotted line suggests significance at P<1×10–5.