CORRELATION OF PROLONGED QTC DISPERSION WITH THE SEVERITY OF CORONARY ARTERY DISEASE DETECTED BY SYNTAX SCORE IN PATIENTS WITH NON-ST SEGMENT ELEVATION MYOCARDIAL INFARCTION

Tapan Chandra Shil*, Amal Kumar Choudury, Md. Mozammel Haque, Humayan Kabir, Pijous Biswas, Jamil Taufiq Imam, Abdul Hamid, Debabrata Halder, Abdullah -Al- Mamun and Bishojit Mondal

ABSTRACT

Determination of the QT interval dispersion by means of a standard ECGat rest has been widely used for cardiovascular risk assessment during the last 15 years as one of the recent explanations for the development of life threatening ventricular arrhythmias. However, littleis known about the relation between QT dispersion and the severity of coronary artery atherosclerosis as defined by SYNTAX score. The present study was done to assess the correlation between QTc dispersion and these verities of coronary artery disease in acute Non-ST elevation myocardial infarction detected by SYNTAX score. This cross sectional observational study conducted in the NICVD, Dhaka It included 100 patients of Non-STEMI underwent coronary angiography in NICVD. QT dispersion was calculated as the difference between the longest(QT max) and the shortest QT (QTmin) interval recorded by standard 12 lead ECG. The QT interval was corrected by using Bazett’s formula (QTc = QT/square root of R-R interval in seconds).Corrected QT dispersion (QTcd) was defined as the difference between the maximum and minimum QTc for a given heart rate. Normal QTcd was 45+_15 ms(chugh,2014),and prolong QTcd was 60ms. The SYNTAX score is calculated by syntax calculator, a new tool to grade the complexity of coronary artery disease.100 participating patients, there were divided into two groups. In Group 1 mean age 48.9 ± 5.8 years and in group-ll mean age was 47.6 ± 8.5years.The mean QTc dispersion was 45 ± 15 ms, while mean SYNTAX score was 19.3 ± 9.3. in group-1 and 11.9 ± 8.6 years There is a strong positive correlation between QTc dispersion and SYNTAX score.QTc dispersion has emerged as a noninvasive measurement for quantifying the degree of myocardial repolarization inhomogeneity. QTc dispersion>60 ms had independent predictive value for the severity of coronary artery disease. The greater the QTc dispersion the higher the number of coronary artery involvement. We observed that there is a positive correlation between prolonged QT dispersion and coronary artery disease severity in terms of syntax score.

Keywords: QTc dispersion; SYNTAX score; Non-STEMI.