Relation of Myocardial Perfusion Abnormalities to Increased QT Dispersion and Value of QT Dispersion in Identification of High-risk Patients With Coronary Artery Disease

This study sought to evaluate the relation of myocardial perfusion abnormalities to increased QT dispersion (QTd) and the relationship between QTd and scintigraphic high-risk parameters providing prognostic information in patients with coronary artery disease (CAD). 1ı2 consecutive patients (52±9 yrs) referred to exercise Tl-20 ı scintigraphy were studied, using reinjection protocol. SPECT images were divided into 20 segments; each segment was classified as normal, reversible defect, viable or nonviable fixed defect. Accordingly, cases were divided into 4 groups as normal subjects (n=45), patients with only reversible defects (n=28), patients with only nonviable fixed defects (n=22) and patients w ith reversible, viable and nonviable defects (n= ı7). Involvement of 5 or more segments, increased lung Tl-201 uptake and transient left ventricular dilatation were considered as scintigraphic high-risk parameters. QTd was defined as the difference between maximal and minimal QT intervals in at least 8 leads of the surface ECG. Mean QTd was 39±9 msec in normal subjects, 62±20 msec in patients with only reversible defects, 65±22 msec in patients with only nonviable fixed defects and 67± ı9 m see in the remaining patients. There was a significant difference between normal subjects and patient groups (pKeywords: QT dispersion, exercise Tl-201 scintigraphy