QT dispersion in single coronary artery disease: Is there a relation between QT dispersion and diseased coronary artery or lesion localization?

It has been shown that QT dispersion (QTD) increases during episodes of myo cardial ischemia or infarction. However, no extensive data on the relation between the diseased coronary artery or the localization of stenosis and th e QTD are available. The aim of the study was to examine the relation betwe en QTD and diseased coronary artery and lesion localization during exercise stress test in patients with single coronary artery disease without prior myocardial infarction. One hundred nineteen patients with single coronary artery disease and 53 pa tients with normal coronary arteries were enrolled in study. Aii patients u nderwent exercise stress test with modified Bruce protocol, and QT interval parameters were measured at rest and at minute 2 of the recovery (rec-2) p eriod. QT dispersion at rest was found higher in all single-vessel disease groups compared with that in the control group, and corrected QT dispersion at rec-2 period was also markedly higher in left anterior descending, circ umflex, and right coronary artery groups compared with that in the control group. No relation was found between QT dispersion and diseased coronary ar tery or the lesion localization. In conclusion, no qualitative difference was found between QT dispersion an d diseased coronary artery or proximal or distal lesion localization. Howev er, it was observed that patients with single-vessel disease had wider base line QT dispersion as compared with that in the control group, which furthe r increased significantly with exercise. This finding supports the idea tha t severity of localized ischemia rather than extent of coronary artery dise ase would be expected to have a greater effect on inducible QT dispersion.