心血管疾病与诊断

Cardiac Troponin I Level in STEMI and Clinical Correlation with Left Ventricular Dysfunction in Indian Population

Abstract

Brijesh Kumar Yadaw, Neera Sharma, A.K Varshney, Lokesh Sharma, Rajnish Singh and Ranjit Kumar Nath

Objective: To determine the relationship of serum troponin I after first acute myocardial infarction with left ventricular ejection fraction as assessed by echocardiography.

Methods: A total of 40 patients of acute myocardial infarction were included in the study. Troponin I concentration was measured by ELISA method and echocardiographic ejection fraction was calculated by modified Simpson’s rule. Echocardiographic ejection fraction was compared with serum troponin I concentration. Patients with previous myocardial infarction were excluded.

Result: There was strong negative correlation between troponin I concentration and left ventricular ejection fraction, i.e., with an increasing troponin level, there was a fall in ejection fraction. The Pearson’s correlation coefficient was –0.69, which was statistically significant (p<0.0001). In our study, we observed that patients with ejection fraction >50%, though small in number were having cTnI levels at 24 hrs ≤ 8 ng/ml. Patients with ejection fraction <50% (left ventricular systolic dysfunction) were having cTnI levels at 24 hrs ≥ 17 ng/ml. Therefore a presumptive cut off level of cTnI ≤ 8 ng/ml may be taken to consider normal left ventricular systolic function in STEMI. The normal range of Troponin I in apparently health individual without STEMI was observed to be <1.0 ng/ml. The mild increase in Troponin I at 24 hrs of STEMI with preserved EF >50% may be due to peak value of biomarker achieved at 24-36 hrs after myocardial injury as most of troponin I are attached to myofibrils.

Conclusion: Serum troponin I concentration has a strong negative correlation with left ventricular ejection fraction after first acute myocardial infarction, and hence can be used to assess the LVEF in patients with first myocardial infarction. An observation was made that a cut off level of cTnI ≤ 8 ng/ml was associated with normal left ventricular systolic function.