Low Level of First Morning Urine Cardiac Troponin I: A Specific Hallmark of Aortic Stenosis Severity

Background: It has recently been shown that cardiac-specific troponin I concentrations in first morning urine samples can be measured with commercially available tests. Due to their accumulation in the first morning urine, scientific papers indicate a potential predictive value for cardiovascular diseases. Therefore, the aim of this study was to compare the concentration of cardiac troponin I in the first morning urine in patients with severe aortic stenosis and the healthy population. Patients and Methods: Blood and first morning urine samples were collected from 34 healthy individuals (17 female) at University Hospital Merkur and 25 patients with severe aortic stenosis (14 female) before surgical treatment at University Hospital Dubrava. Cardiac troponin I and T values were determined using high-sensitivity assays using commercially available Abbott and Roche tests. Results: Patients with severe aortic stenosis had significantly lower troponin I concentrations in the first morning urine samples (0.3 ng/L (0.1-0.6)) as compared to the healthy population (15.2 ng/L (8.4-19.9)) (p < 0.001). There was no statistically significant difference in troponin T concentrations between healthy individuals and patients with severe aortic stenosis. In parallel, both I and T plasma troponin concentrations were significantly higher in patients with severe aortic stenosis. Conclusions: In patients with severe aortic stenosis, cardiac troponin I values in the first morning urine are significantly lower than in healthy subjects.