Cardiac troponin T and I are differentially associated with myocardial fibrosis assessed by cardiac magnetic resonance imaging
Authors: Paus M , Wimalanathan T , Skranes J B , Berge T , Tveit A , Roesjoe H , Omland T , Heck S L , Lyngbakken M N 
Published: November 2023

Abstract

Background
Cardiac troponin T (cTnT) is more potently associated with non-cardiovascular (CV) mortality and cardiac troponin I (cTnI) is more specific for CV risk in the general population. Cardiovascular magnetic resonance imaging (CMR) measurement of extracellular volume (ECV) allows for assessment of diffuse myocardial fibrosis and is associated with adverse CV events. Focal myocardial scars are assessed by late gadolinium enhancement (LGE) and LGE scar presence is associated with unfavorable CV outcomes. The distinct clinical outcomes associated with cTnT and cTnI may be due to different subtypes and burden of myocardial fibrosis. Elevation of cTnT associates with increased ECV in a CMR referral base and with nonischemic myocardial scars in the general population. There is limited data comparing the associations of cTnT and cTnI with CMR indices of fibrosis in the general population.

Purpose
Perform head-to-head comparison of the associations of cTnT (Roche Elecsys) and cTnI (Abbott Alinity) with diffuse and focal myocardial fibrosis assessed by CMR.

Methods
Two hundred community-dwellers born in 1950 with approximately similar sex distribution were recruited. All participants were without contraindications to contrast-enhanced CMR, had normal kidney function and no known coronary artery disease. For the study a 1.5-T Philips MRI clinical scanner was used. Diffuse fibrosis was estimated by septal ECV and focal scars were quantified by LGE and classified as either ischemic or nonischemic. Complete MOLLI-sequence for assessment of ECV was present in 192 participants and 198 participants had complete LGE sequence. Logistic regression analysis was used to examine relationships between log transformed cardiac troponins and CMR indices of myocardial fibrosis, adjusting for a priori selected established cardiovascular risk factors. We analyzed ECV according to cut-off values based on the upper sex-specific quartile.

Results
The median age was 69 (68.6-69.3) and 52% were male (Table 1). The upper sex-specific quartile of ECV was 27% for men and 28% for women. cTnT was associated with ECV in the fully adjusted model (odds ratio [OR] 1.98, 95% CI 1.08-3.64), in contrast to cTnI which was not associated with ECV in any of the models (Table 2). cTnT (OR 3.71 95% CI 1.83-7.50) and cTnI (OR 1.69 95% CI 1.24-2.30) were associated with the presence of any LGE scar in the fully adjusted model, but the association was stronger for cTnT (p for comparison = 0.024). cTnT and cTnI were significantly associated with nonischemic scars in all models (Table 2), but stronger for cTnT (p for comparison = 0.018). In the fully adjusted model only cTnI was associated with the presence of ischemic scars (OR 1.66 95% CI 1.05-2.61).

Conclusion(s)
In our cohort of community-dwellers, cTnT is the stronger marker of diffuse and nonischemic myocardial fibrosis, while cTnI seems to more strongly reflect the presence of ischemic scar as assessed by CMR.Participant characteristicsAssociations of cTnT and cTnI