Prognostic significance of the distortion of terminal portion of QRS complex on admission electrocardiogram in ST segment elevation myocardial infarction.

BACKGROUND: ECG on admission has been used in predicting prognosis and risk stratification in ST segment elevation acute myocardial infarction (STEMI). OBJECTIVE: To analyze the admission ECG in STEMI based on abnormality observed in terminal portion of QRS and its correlation to hospital mortality. METHOD: 160 consecutive patients of STEMI were classified into subjects without (Group I) and with distortion of terminal QRS (Group II), Pattern A--Emergence of J point at ≥50% of the R wave amplitude in leads with qR configuration or Pattern B--Absence of the S waves, in leads with Rs configuration in two consecutive leads. RESULTS: Out of 160 patients of STEMI, 69 (43.1%) had distortion of QRS. There were 13 deaths (8.1%). Hospital mortality was found to be significantly more in subjects with distortion than those without (15.9% V/S 2.1%, p < 0.001). Patients with QRS distortion tended to have larger infarction as assessed by Killip class on admission (p < 0.05), anterior location of MI (p < 0.01) and presence of significant Q waves in leads with ST segment elevation (p < 0.0001). With multiple logistic regression analysis using hospital mortality as a dependent variable and all studied risk factors as independent variables, QRS distortion on admission ECG was the only variable found to be statistically significant (Adjusted OR = 7.161, p < 0.05). CONCLUSION: ECG on admission is a simple, cheap, universally available investigation that can predict the short term prognosis in STEMI and would help in deciding which patients should go for other myocardial revascularization procedures.

QT dispersion and early arrhythmic risk in acute myocardial infarction.

BACKGROUND: This study sought to find out QT dispersion in healthy individuals and patients of acute myocardial infarction and to find correlation, if any, between QT dispersion and the incidence of ventricular arrhythmias in acute myocardial infarction. METHODS AND RESULTS: QT dispersion was calculated from a 12-lead electrocardiogram in 100 patients of acute myocardial infarction admitted in intensive coronary care unit and 100 age- and sex-matched healthy individuals. In patients of acute myocardial infarction, QT dispersion was calculated on admission, 24 hours after admission and at the time of discharge from intensive coronary care unit. Average QT dispersion in acute myocardial infarction was found to be significantly higher on admission (76.4 +/- 18.3 ms), 24 hours after admission (62.88 +/- 17.52 ms) and at the time of discharge from intensive coronary care unit (51.79 +/- 16.79 ms) than in healthy individuals (29.76 +/- 6.06 ms; p<0.05). QT dispersion was found to be significantly increased in patients of acute myocardial infarction with ventricular arrhythmias (82.06 +/- 16.86 ms) than in those without (66.75 +/- 16.28 ms; p<0.01). Patients of acute myocardial infarction with ventricular tachycardia or ventricular fibrillation had significantly increased QT dispersion (96.25 +/- 15.97 ms) than those who had only ventricular premature beats (80 +/- 15.04 ms; p<0.01). QT dispersion was found to be significantly greater in patients with anterior wall acute myocardial infarction (79.80 +/- 18.19 ms) than in those with inferior wall acute myocardial infarction (71.9 +/- 17.48 ms; p<0.05). At the time of discharge from intensive coronary care unit no statistically significant difference was found in QT dispersion in those who received thrombolysis (51.58 +/- 16.05 ms) and those who did not (48.18 +/- 14.68 ms; p>0.05). QT dispersion was found to be significantly higher in those who died (88.66 +/- 15.97 ms) than in those who survived (74.23 +/- 17.91 ms; p<0.05). QT dispersion was significantly higher in ventricular arrhythmic deaths (97.14 +/- 17.04 ms) than those who had non-arrhythmiac deaths (81.25 +/- 11.25 ms; p<0.05). CONCLUSIONS: Interlead QT variation and its measure as QT dispersion challenges our current approach to the electrocardiographic assessment of arrhythmic risk. QT dispersion may provide a potentially simple, cheap, non-invasive method of measuring underlying dispersion of ventricular excitability.