ROLE OF CARDIAC BIOMARKERS IN ACUTE MYOCARDIAL INFARCTION

Abstract

Acute myocardial infarction (AMI) remains one of the leading causes of morbidity and mortality worldwide, affecting both developed and developing countries. Despite significant advances in diagnostic modalities and therapeutic strategies over recent decades, AMI continues to pose a major public health challenge, particularly in low- and middle-income nations undergoing rapid epidemiological transition. The diagnosis of AMI traditionally relies on a combination of clinical features, electrocardiographic (ECG) changes, and biochemical markers of myocardial injury such as creatine kinase (CK), creatine kinase-MB (CK-MB), lactate dehydrogenase, and cardiac troponins. However, conventional enzymes like CK and CK-MB lack absolute myocardial specificity and may be elevated in several non-cardiac conditions, thereby limiting their diagnostic accuracy. Cardiac troponin I (cTnI), owing to its high myocardial tissue specificity and sensitivity, has emerged as the gold standard biomarker for the early diagnosis of myocardial injury.

Materials and Methods: This hospital-based case–control study was conducted in the Department of Biochemistry, Subbaiah Institute of Medical Sciences and Research Centre, Shivamogga, Karnataka over a period of 1 year. Thirty apparently healthy individuals without risk factors for coronary artery disease served as controls, while 30 patients admitted to Hospital, with acute chest pain and ECG changes suggestive of AMI constituted the study group. Venous blood samples were collected, and serum was analyzed for cardiac biomarkers including troponin I, CK-MB, and total CK, along with lipid profile parameters—total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and triglycerides (TG). Statistical analysis was performed to compare mean values between controls and cases, and sensitivity and specificity of biomarkers were calculated.

Results: The mean serum troponin I levels were significantly elevated in AMI patients compared to controls (4.439 ± 3.229 µg/ml vs 0.012 ± 0.006 µg/ml; p < 0.001). CK-MB and CK levels were also markedly increased in cases (97.067 ± 80.439 U/L and 233.767 ± 92.565 U/L, respectively) compared to controls (8.794 ± 6.041 U/L and 59.207 ± 18.831 U/L; p < 0.001). Troponin I demonstrated 100% sensitivity and 100% specificity for the diagnosis of AMI, outperforming CK-MB and CK. Lipid profile analysis revealed significantly higher levels of TC, LDL, VLDL, and triglycerides and significantly lower HDL levels in AMI patients compared to healthy controls (p < 0.001).

Conclusion: The study highlights that cardiac troponin I is a superior, highly sensitive, and specific biomarker for the early diagnosis of acute myocardial infarction compared to CK and CK-MB. Additionally, significant dyslipidemia observed in AMI patients underscores the critical role of lipid abnormalities as major risk factors for ischemic heart disease. Early detection of myocardial injury using troponin I, along with aggressive management of lipid disorders, may contribute to improved clinical outcomes in patients with AMI.