New Cutoff for High Sensitivity Troponin to Better Risk Stratify Patients with Non-ST Elevated Myocardial Infarction

Background: The diagnosis of Non-ST Elevated Myocardial Infarction (NSTEMI) is dependent on elevation of high sensitivity troponin (Hs-troponin). The current cutoff point for Hs-troponin is highly sensitive but not specific for obstructive coronary artery disease (CAD). This study aims to determine the best cutoff point for diagnosing CAD in patients presented with NSTEMI. Methods: Our study included all patients admitted as NSTEMI that underwent coronary angiography (CAG). They were grouped into two groups: A and B. Group A has obstructive CAD of 70% or more stenosis and group B with non-obstructive CAD. Patients were assessed for their demographics, clinical history, laboratory and imaging results. Using SPSS version 22, the pooled cohort of patients were analyzed at significant level < 0.05 and the data were tested for significant correlations between two predetermined groups. Results: Group A comprised 87.6% of the patients and both groups had a median age of 53 years. In Group A, 91% were males, 54% diabetics, 54% hypertensives, and median Hs-troponin was 145 ng/L. While in group B, 88% were males, 39% diabetics, 60% hypertensives, and median Hs-troponin was 54 ng/L. There was significant correlation between the two groups in the percentage of diabetes and median troponin level (p < 0.05). A ROC curve has identified a level of 127 ng/dL as the best cutoff of Hs-troponin in detecting obstructive CAD (p = 0.03). Interestingly, 60% of patients in group B had alternative diagnoses. Conclusion: Hs-troponin is sensitive but less specific for obstructive CAD. However, increasing its cutoff value will improve its specificity.