The Role of 12-Lead Electrocardiogram in the Risk Stratification of Non-St Elevation Acute Coronary Syndrome and the Correlation with Coronary Angiography - The CINCHONA Study - A Prospective Cohort Study in Northern India

BACKGROUND: Clinical guidelines recommend risk stratification of non-ST elevation acute coronary syndrome (NST-ACS) using the GRACE risk score. However, the GRACE risk score is not followed widely in clinical practice due to various reasons. Our primary objectives of this study were to correlate the presenting electrocardiogram (ECG) of NST-ACS with coronary angiography (CAG) findings and to identify specific ECG changes that are suggestive of severe coronary artery disease (CAD) thus helping to triage all patients with NST-ACS. MATERIALS AND METHODS: This prospective observational study was undertaken on patients diagnosed with NST-ACS in a medical college hospital, in Northern India over one and a ½ years. The admission ECG of the patients was compared with CAG findings to find out the correlation between the two with respect to severity of CAD. Categorical and quantitative variables were compared using the Chi-square test and independent t-test, respectively. Odds ratio (OR) were calculated using the univariate logistic regression analysis. RESULTS: On comparing the two groups with normal and abnormal ECG, we found that smokers had significantly higher odds of having an abnormal ECG (OR 3.31; 95% confidence interval [CI] [1.29–8.50]). Patients with an abnormal ECG had significantly lower left ventricular ejection fraction compared to those with normal ECG (52.01 ± 10.56 vs. 55.96 ± 6.13%, P = 0.045). The patients with severe CAD on CAG had significantly higher odds of abnormal ECG (OR 3.68, 95% CI [1.2311.04]). Of the specific ECG abnormalities, ST depression and T-wave inversion in same or different leads were significantly associated with severity of CAD (OR 0.13, 95% CI [0.04–0.43], P = 0.001 and OR 0.13, 95% CI [0.03–0.46], P = 0.002, respectively). CONCLUSION: The identification of ECG changes suggestive of high-risk CAD can dictate to transfer such patients without delay to a percutaneous coronary intervention capable hospital for urgent CAG with intent to revascularization, thus helping in risk stratification of NST-ACS at the community level.