High-Sensitivity Troponin I and Coronary Computed Tomography in Symptomatic Outpatients With Suspected CAD: Insights From the PROMISE Trial

Objectives: The goal of this study was to examine associations between concentrations of high-sensitivity troponin I (hsTnI)(measured by using a single-molecule counting method)and obstructive coronary artery disease (CAD)in 1,844 stable, symptomatic outpatients with suspected CAD randomized to undergo coronary computed tomography angiography (CTA)in the PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain)trial. Background: Elevated concentrations of hsTnI are associated with CAD in patients with myocardial infarction. The meaning of hsTnI concentrations in stable symptomatic outpatients is not well understood. Methods: Clinical characteristics and CTA results (including coronary artery calcium [CAC]scores)were expressed across hsTnI quartiles. Determinants of hsTnI concentration were identified. Multivariable logistic regression identified independent predictors of obstructive CAD₅₀ (≥50% stenosis in any vessel)and CAD₇₀ (≥70% stenosis or ≥50% left main). Results: The median hsTnI concentration was 1.5 ng/l; nearly all (98.5%)subjects had measurable hsTnI, and 6.1% had concentrations ≥99th percentile concentration for this assay (6 ng/l). Higher CAC scores, as well as more prevalent and diffuse CAD, was seen in upper hsTnI quartiles (all p < 0.001). Independent predictors of hsTnI concentrations included age, sex, and CAC score (all p < 0.05). After adjusting for demographic and clinical characteristics, log-transformed hsTnI concentrations were associated with obstructive CAD₅₀ (odds ratio: 1.15 per interquartile range; p = 0.02)and CAD₇₀ (odds ratio: 1.25 per interquartile range; p = 0.001). Conclusions: In stable symptomatic outpatients undergoing nonemergent coronary CTA for the diagnosis of suspected CAD, higher concentrations of hsTnI were associated with increasing presence and severity of coronary atherosclerosis.