High-Sensitivity cardiac troponin I in the diagnosis of acute myocardial infarction: A study in patients with renal insufficiency.

Background: Patients with chronic kidney disease (CKD) exhibit a heightened risk of myocardial infarction. Chronic elevation of cardiac troponin levels frequently occurs in CKD patients, thereby diminishing their diagnostic utility in the evaluation of suspected non-ST-segment elevation acute myocardial infarction (NSTE-AMI). This study aimed to assess the diagnostic performance of initial high-sensitivity cardiac troponin I (hs-cTnI) for AMI in populations with and without chronic kidney disease. Methods: A total of 142 consecutive CKD patients attending the nephrology outpatient clinic were enrolled to investigate the association between baseline hs-cTnI concentrations and estimated glomerular filtration rate (eGFR). In parallel, A total of 237 CKD patients presenting to the emergency department with suspected NSTE-AMI were consecutively recruited, alongside a control group of 261 individuals with normal renal function. Receiver operating characteristic (ROC) curves assessed hs-cTnI diagnostic performance, with subgroup comparisons. Results: CKD patients exhibited significantly higher median hs-cTnI levels which correlated inversely with eGFR (p < 0.001). The incidence of adjudicated NSTE-AMI was higher in the CKD cohort (18.1 % vs. 6.9 % in controls, p < 0.001). Diagnostic accuracy of initial hs-cTnI did not differ significantly between groups, as reflected by comparable AUC values (0.949 in CKD vs. 0.937 in controls, P = 0.783). However, specificity for NSTE-AMI was lower in CKD (60.1 % vs. 90.6 %, p < 0.001), which can be restored by applying a higher cutoff. Conclusions: Despite of reduced specificity in patients with CKD, hs-cTnI continues to be a valuable diagnostic marker. Adopting higher diagnostic thresholds and prospectively validating them may lead to improved diagnostic performance.