High-Sensitivity Troponin in Patients With Coronary Artery Endothelial Dysfunction

BACKGROUND: Coronary endothelial dysfunction (CED) is associated with recurrent ischemia. The role of high-sensitivity cardiac troponin I (hscTnI) levels in patients with CED has not been established. METHODS: Patients with suspected ischemia, who underwent clinically indicated coronary angiography and were found to have non-obstructive coronary artery disease, were included in the study. CED was defined as ≤50% increase in coronary blood flow from baseline and/or a decrease in epicardial coronary artery diameter >20% in response to maximal dosages of acetylcholine. HscTnI was measured at the time of the procedure using the Architect hscTnI assay (Abbott). RESULTS: Of 299 patients, 60 had normal endothelial function and 239 patients had abnormal endothelial function. The median age of the population was 52 years (interquartile range [IQR], 45-60 years). Patients with abnormal endothelial function had significantly higher log hscTnI values when compared to patients with normal endothelial function (0.9 ng/L [IQR, 0.7-1.4 ng/L] vs 0.7 ng/L [IQR, 0.7-1.1 ng/L]; P=.04). An hscTnI value >12.5 ng/L was 100% specific for the presence of endothelial dysfunction (100% positive predictive value). There were 39 major adverse cardiovascular events during follow-up. In patients with normal endothelial function, hscTnI levels were significantly higher in patients who developed major adverse cardiac events when compared to patients who did not (1.35 ng/L [IQR, 1.1-2.1 ng/L] vs 0.7 ng/L [IQR, 0.7-1.1 ng/L]; P=.02). CONCLUSION: Our findings suggest that endothelial dysfunction may be associated with higher baseline hscTnI levels, suggesting increased myocardial injury in this population of patients. Additional studies are necessary to further define the role of hscTnI in risk stratification in this population.