QT interval dispersion as a prognostic indicator in patients of acute coronary syndromes

Abstract

Background: QT dispersion is a potential marker of arrhythmic risk, myocardial ischemia and myocardial viability. Measurement of QT interval dispersion has failed to establish its place in routine clinical practice. The study aims at predicting risk of life threatening ventricular arrhythmias in patients of acute coronary syndromes using rate adjusted QT interval dispersion (QTcd) as one of the cheapest modalities of investigation.Methods: Serial measurements (at admission, after 24 hours, 48 hours, and 7th day) of rate adjusted QT interval dispersion (QTcd) was done in 107 cases of acute coronary syndromes (ACS) namely ST-segment elevated Myocardial infarction (STEMI), non-ST-segment elevated myocardial infarction (NSTEMI) and unstable angina (UA). Patients who reported within 12 hrs of onset of chest pain and typical ECG changes were thrombolysed using streptokinase (15 lack IU).Results: Mean QTcd following acute coronary syndrome was maximum at admission and then gradually falls till day-7 as the patients clinical condition improves but it remains high in case of development of various complications (viz. hypotension, congestive heart failure (CHF), PSVT, VPC, CHB, ventricular fibrillation and death). Patients with STEMI who were thrombolysed at admission showed significantly lower mean QTcd on day-1, as well as complications and death during in-hospital stay as compared to patients who were not thrombolysed (p <0.001).Conclusions: QTcd interval could be helpful as an earliest in-hospital bedside predictor of life-threatening arrhythmias and death. Timely reperfusion by thrombolysis decreases mean Qtcd and thus reduces post-MI mortality and morbidity.