Prognostic significance of initial electrocardiogram in patients with ST elevation acute myocardial infarction (STEMI)- A study of 52 cases

摘要

Background: In Acute myocardial infarction patient's surface electrocardiogram allows risk management in individual patients by estimating the size of area at risk. This can be assessed fro m different waveforms of ECG. Settings and Design: In this prospective observational study we studied 52 consecutive patients of ST elevation acute myocardial infarction admitted into a teaching hospital. Methods and Material: The electrocardiogram of acute myocardial infarction patients which showed ST segment elevation of 1mm in two or more limb leads or 2mm in two or more chest leads with positive T waves in leads with ST segment elevation was analyzed in relation to ECG heart rate, number of leads showing ST segment deviatio n, ST segment deviation score, grades of ischemia as assessed by terminal portion o f QRS complex. Out of 52 patients studied, mortality occurred in eight patients within seven days o f hospital stay. Thus we had two groups of patients, one who survived seven days of hospital stay(n=44) and other who did not survive seven days of hospital stay(n=8).These ECG parameters between these two groups were compared to determine value of ECG in predicting short term mortality. Mean values with standard deviation were calculated for continuous variables. Chi square tests were used to determine the significance of difference between proportions for discrete variables and p value of less than 0.05 was considered statistically significant. Results: Mean heart rate on admission was 84 beats per minute ranging from 32 to 136 beats per min. Tachycardia on admission was present in 17 patients who had high mortality than that in patients with normal heart rate( 17.3 and 14.2%respectively.) The mean ST segment deviation score was 22.69 ranging from 6 to 45.The high ST segment deviation score was associated with increased mortality at 7 days.(p=0.0209).Similarly in patients with ECG showing more number of leads showing ST segment deviation mortality was high(p=0.009).Mortality in patients (n=27) with grade III ischemia (terminal QRS distortion) was significantly more than that in patients (n=25) with grade II ischemia(without distortion of terminal QRS complex)(p=0.0385). Conclusions: Tachycardia, high ST segment deviation score, more number of leads with ST segment deviation, distortion of terminal portion of QRS comp lexes on admission ECG denoted poor short term prognosis.