Correlation of Standard ECG with 2D-Echo and Serum Troponin I in Locating the Site of Myocardial Infarction and its Extent- An Observational Study

Abstract

Introduction: Cardiovascular diseases are the leading causes of death in developed countries, and its incidence is on the rise in developing countries. Electrocardiogram (ECG), 2 Dimensional Echocardiography (2D-Echo) and myocardial injury biomarkers help in the diagnosis, prognostification of Myocardial Infarction (MI). Aim: To correlate the findings of ECG, 2D-Echo and Troponin I levels in locating the site and extent of MI. Materials and Methods: This observational study was conducted in the Cardiology Intensive Care Unit (ICU)/ward, PES Hospital, Kuppam, Andhra Pradesh, India, from January 2019 to June 2020. A total of 99 patients of acute MI were studied at baseline, and repeat 12 lead ECG, 2D-Echo and serum troponin I levels were recorded. Ejection Fraction (EF) was estimated from the QRS score by means of a formula, and Echocardiographic correlation was obtained on the same day with ECG-QRS scoring by direct estimation of EF in ‘Q’ wave infarction. High sensitivity cardiac Troponin – I was measured at the time of hospitalisation and repeated at six hours if required, and its levels were correlated to the extent of MI i.e., Left Ventricular Ejection Fraction (LVEF). The categorical data were analysed using Chi-square test and p<0.05 was considered as statistically significant. Regression analysis was done for associated factors. Results: There was better correlation between EF calculated from ECG-QRS scoring system and 2D-Echo (r=0.78, p-value <0.001). There was poor correlation between serum Troponin I levels at admission, and extent of MI i.e., LVEF as estimated by ECG and 2D-Echo (r=-237.13, p=0.334 and r=-120.78, p=0.585). There was a significant correlation between serum Troponin I levels at 72 hours of chest pain or peak values and extent of MI i.e., LVEF as estimated by ECG and 2D-Echo (r=-1446.14, p<0.001 and r=-1354.42, p<0.001). Conclusion: The location of MI, seen on ECG, correlated broadly with those seen on 2D-Echo. 2D-Echo was able to elaborate regional wall motion abnormalities in detail when compared to the ECG. LVEF can be calculated from ECG at bedside in Q wave infarction, which correlated fairly with 2D-Echo findings.

Keywords

• electrocardiogram qrs scoring system
• left ventricular ejection fraction
• q wave infarction
• regional wall motion abnormalities