Effectiveness of the electrical risk score in predicting in-hospital and post-hospital mortality in acute coronary syndrome patients without ST elevation

Introduction: Acute coronary syndrome (ACS) is the definition of clinical events that occur as a result of partial reduction or complete disruption of myocardial circulation. Electrical risk score (ERS); is a new risk scoring system consisting of heart rate, left ventricular hypertrophy (Sokolow- Lyon criteria), QRS transition zone, frontal QRS-T angle, corrected QT interval (QTc) and T peak to T end (Tp-e) interval. In previous studies, these parameters were studied separately in patients with non-ST segment elevation myocardial infarction (NSTEMI). However, to our knowledge, there is no study evaluating ERS in patients with NSTEMI. The aim of the study is to examine the effect of ERS on in-hospital and post-hospital complications in patients with NSTEMI. Methods and materials: In the study, 427 consecutive patients with NSTEMI who were hospitalized in the coronary intensive care unit of our hospital between January 2020 - November 2021 were included retrospectively. Demographic, echocardiographic and laboratory data of the patients were obtained from the hospital archive records. Electrocardiography (ECG) of all patients were evaluated in detail. ERS parameters were scored as follows: heart rate >75, presence of left ventricular hypertrophy according to Sokolow-Lyon criteria, QRS transition zone ≥ V4, frontal QRS-T angle >90o, QTc interval > 450 msec in men, > 460 msec in women and Tp-e interval > 89 msec. The ERS of all patients was calculated according to the number of abnormal findings in the ECG. The patients were divided into two groups as ERS < 3 and ERS ≥ 3 and comparisons were made. Results: No significant difference was found between ERS ≥3 and <3 groups in terms of demographic characteristics. However, when compared with patients with ERS <3; patients with ERS ≥ 3 had significantly higher glucose (p = 0.001), urea (p = 0.006), creatine (p = 0.008), leukocytes (p = 0.011), maximum troponin (p < 0.001) and TIMI (p = 0.002) and GRACE (p < 0.001) risk scores, whereas lower left ventricular ejection fraction (LVEF) (p < 0.001). When evaluated in terms of angiographic findings; the frequency of 3-vessel disease (p = 0.001) and the SYNTAX score (p < 0.001) were found to be significantly higher in patients with ERS ≥ 3. Considering in-hospital and post hospital adverse events; inotrope need (p < 0.001), mechanical ventilation support (p < 0.001), ventricular arrhythmia frequency (p < 0.001), acute renal failure (p < 0.001), in-hospital mortality (p < 0.001) and 6.th months mortality rate (p = 0.002) were found to be significantly higher in patients with ERS ≥ 3. It was found that as the number of abnormal findings on the ECG increased, the frequency of these poor outcomes gradually increased. In the correlation analysis, positive correlation was detected between ERS and maximum CK-MB (r=0.285; p < 0.001 ), maximum troponin(r=0.410; p < 0.001 ), TIMI(r=0.002; p = 0.002 ), GRACE(r = 0.243; p < 0.001 ) and SYNTAX scores (r = 0.427; p < 0.001); whereas negative correlation was detected between ERS and LVEF (r = -0.363, p < 0.001). In ROC curve analysis, ERS ≥2.5 was found to predict in-hospital mortality with a sensitivity of 69.2% and specificity of 77.1% (Area under the curve: 0.798, 95% confidence interval: 0.675-0.921, p < 0.001). In logistic regression analysis, ERS (odds ratio [OR]: 1.790, 95% confidence interval [CI]: 1.036-3.095, p = 0.037), ventricular arrhythmia (OR: 7.057, 95% CI: 1.755-28.378, p = 0.006) and the GRACE (OR: 1.030, 95% CI: 1.010-1.051, p = 0.004) risk score were determined as independent predictors of in-hospital mortality. Conclusion: In the study, we found that the frequency of in-hospital and post-hospital adverse events were significantly higher in NSTEMI patients with an ERS ≥ 3 at admission. This simple electrocardiographic risk marker can help identify patients at higher cardiac risk in patients presenting with NSTEMI and identify patients who may need early intervention. Keywords: Electrocardiography, Electrical risk score, Myocardial infarction without ST elevation