A Study of QT Dispersion in Acute Myocardial Infarction

Abstract

Background and Objectives: Despite tremendous advancements in the detection and management of Acute Myocardial Infarction over the last three decades, coronary artery disease remains the major cause of cardiovascular mortality worldwide. Arrhythmias are the leading cause of abrupt cardiac mortality in patients with Acute MI. With the awareness that patients with long QT intervals are at a higher risk of sudden cardiac death, this report concentrated on QT interval analysis and goes a step further by investigating QT dispersion in Acute Myocardial Infarction and its association with arrhythmias. Methods: This prospective study was done in 100 patients of AMI, satisfying inclusion and exclusion criteria. Along with basic evaluation and investigations, ECG was done at admission, at 24 hours and at discharge. QT dispersion was calculated using formula: QTd= QT max- QT min. Results: The study consisted of 80 AMI patients with mean age of 55.8 years including both male and female patients. It included both thrombolysed and not thrombolysed patients and anterior and inferior wall patients. Among 80 patients, 24 developed ventricular arrhythmias – VPCs, VT, VF. The QTd in AMI patients was 80.71 ± 18.4ms. The QTd in patients with arrhythmias was 93.8 ±17.1ms and in those without is 70.1±9.7ms Interpretation and conclusion: Mean QT dispersion is significantly increased after Acute Myocardial Infarction. QT dispersion shows a dynamic decrease with time. Mean QT dispersion levels are higher in patients with ventricular tachycardia and ventricular fibrillation compared to patients with Acute Myocardial Infarction without these arrhythmias. The change in QT dispersion are dynamic, and it may serve as a non-invasive marker of susceptibility to malignant ventricular arrhythmias.