DIFFERENTIATING TROPONIN I AND CK-MB IN MYOCARDIAL INFARCTION DIAGNOSIS: A NOVEL APPROACH TO BIOMARKER COMPARISON

Background: Myocardial infarction (MI) is a life-threatening condition characterized by reduced blood supply to cardiac tissue, often leading to irreversible myocardial damage. Early and accurate diagnosis is essential to reduce complications and mortality. Biomarkers such as cardiac Troponin I (cTnI) and Creatine Kinase-MB (CK-MB) are central to MI detection. While cTnI is highly specific to cardiac tissue, CK-MB plays a supplementary role, especially in identifying reinfarction due to its shorter half-life and rapid kinetics. Objective: To compare the diagnostic sensitivity and specificity of Troponin I and CK-MB in patients with acute myocardial infarction (AMI) and to determine the broader diagnostic window and reliability of Troponin I in both early and late phases of MI. Methods: This cross-sectional, retrospective study included 65 MI patients (69.23% females, 30.77% males) with a mean age of 53 years, conducted over four months at two tertiary hospitals in Lahore. Blood samples were collected within six hours of symptom onset and analyzed using Beckman Coulter AU480 and Microlab 300 analyzers. Descriptive statistics, Pearson correlation, independent t-tests, and ROC curve analysis were used. Troponin I and CK-MB levels were compared for diagnostic accuracy, gender-based differences, and inter-marker correlation using SPSS version 25, with significance set at p < 0.05. Results: Troponin I demonstrated a sensitivity of 95% and specificity of 97.4%, compared to CK-MB’s sensitivity of 96.4% and specificity of 85.8%. Mean Troponin I was 25.41 ng/mL (SD = 15.86) and CK-MB was 118.87 ng/mL (SD = 57.43). Pearson correlation showed a weak, non-significant relationship (r = 0.023, p = 0.859). ROC analysis revealed higher diagnostic accuracy for Troponin I (AUC = 0.92) versus CK-MB (AUC = 0.78). No significant gender-based differences were noted. Conclusion: Troponin I outperforms CK-MB in terms of diagnostic accuracy, specificity, and clinical reliability for myocardial infarction. CK-MB may retain value in early detection, but Troponin I should remain the primary biomarker for precise diagnosis. Future research should focus on integrating additional biomarkers to further enhance diagnostic strategies.