High-Sensitivity Cardiac Troponin T Assessment to Improve Cardiovascular Risk Prognostication in Patients with Chronic Kidney Disease: Ready for Prime Time?

Cardiac troponin, an established biomarker of myocardial injury, plays a key role in the management of patients with suspected acute coronary syndromes. Apart from the potential advantage of high-sensitivity cardiac troponin-T (hscTn-T) in the early detection of acute myocardial infraction, recent evidence suggests that the serum levels of this biomarker reflect underlying sub-clinical myocardial damage. For example, cross-sectional studies conducted in asymptomatic patients with chronic kidney disease (CKD) showed that hs-cTn-T is associated with both electrocardiographic and echocardiographic indicators of sub-clinical myocardial dysfunction. Prospective observational studies also provided evidence that among patients with CKD, elevations in hs-cTn-T are independently associated with greater likelihood for incident atrial fibrillation (AF) and heart failure (HF), progression of kidney injury to end-stage kidney disease (ESKD), and increased long-term risk for all-cause and cardiovascular (CV) death. Most importantly, comparative studies showed that the prognostic association of hs-cTn-T with CV morbidity and mortality is at least similar in the CKD population with that in patients with normal kidney function. In this issue of Angiology, Hajjari et al. report the results of a post-hoc analysis of the Chronic Renal Insufficiency Cohort (CRIC) study that explored the association of hs-cTn-T with the risk of incident stroke in patients with mild-tomoderate CKD. This analysis incorporated 3477 participants without a history of stroke prior to enrollment. Over a median follow-up of 7.3 years, a total of 107 strokes (84 ischemic and 23 hemorrhagic) occurred. Patients stratified within the highest quartile of baseline hs-cTn-T tended to be older, belonged more commonly to the black race, had lower estimated-glomerular-filtration-rate (eGFR) and higher urinary albumin-to-creatinine ratio, and exhibited a higher burden of CV co-morbidities, such as hypertension, diabetes mellitus, AF, HF and peripheral arterial disease. In fullyadjusted Cox-regression models, compared with the hs-cTn-T referent quartile 1, the hazard ratio (HR) for the outcome of incident stroke was 1.41 (95% confidence interval (CI): 0.662. 98) in quartile 2, 1.55 (95% CI: 0.71-3.77) in quartile 3 and 2.55 (95% CI: 1.10-5.57) in quartile 4; the trend across quartiles was statistically significant (HR: 1.34; 95% CI: 1.051.73). Sensitivity analysis showed that the association of hscTn-Twith the risk of incident stroke persisted irrespective of the presence or absence of AF at baseline. The results of this post-hoc analysis of the CRIC study suggest that hs-cTn-T also reflects sub-clinical atherosclerosis, which is associated with excess risk for cerebrovascular disease and stroke. With this background in mind and also taking into consideration the accumulated evidence from prospective observational studies showing that hs-cTn-T is a powerful predictor of adverse CV events and mortality, the clinical utility of hs-cTn-T as a prognostic biomarker in patients with CKD requires further evaluation. High-sensitivity cardiac troponin-T would be useful in daily clinical practice for CV risk prognostication, if it added information over and above that provided by risk prediction scores that are based on easily available clinical parameters. This aspect was explored for 2 other prognostic biomarkers, aortic pulse wave velocity (PWV) and left ventricle (LV) mass index, in the ESKD population. In Cox-regression hazard models, both aortic PWV and LV mass index were significantly and independently associated with greater risk of allcause and CVmortality. However, when the statistical analysis was based on state-of-the-art prognostic tests (i.e. calibration analysis, discrimination analysis and risk re-classification tests), the overall prognostic and discriminatory power of aortic PWVand LVmass index for all-cause and CV death was inferior to that provided by 2 simple clinical risk scores specific to the ESKD population (the Annualized Rate of Occurrence scores). On this basis, although aortic stiffness and LV hypertrophy are important mediators of the