Effects of ischemia and reperfusion on QT dispersion during coronary angioplasty

The effects of ischemia and reperfusion on QT interval dispersion (QTD: QT(max)-QT(min) in the 12-lead ECG) were analyzed in 15 patients (12 males, 57 +/- 13 years) undergoing coronary angioplasty (PTCA). All patients had single-vessel coronary artery disease (only one greater than or equal to 85% stenosis in a major coronary artery) and normal left ventricular function. All were in sinus rhythm with normal atrioventricular and intraventricular conduction on the surface EGG. No patient wets on therapy that could affect the QT interval. The ECG was recorded (all 12 leads simultaneously) at 50 mm/s speed before the first balloon inflation, at the end of the first inflation during PTCA, and at 30'' and 60'' during reperfusion following the first inflation. In order to avoid ischemic preconditioning, only recordings of the first inflation were used. In each tracing QT(max) and QT(min) were valuated. All values were rate corrected using a simple linear equation (QT linear corrected = QT + 0.154 [1-RR]). QTD increased significantly during both ischemia and reperfusion. QT(max) was not changed by ischemia and was increased by reperfusion. QT(min) was reduced by ischemia and increased by reperfusion. These results indicate that both ischemia and reperfusion alter ventricular repolarization, inducing a less homogeneous ventricular recovery pattern.