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 angiopiasty (PTCA). AH patients had single-vessel coronary artery disease (only one ≥ 85% stenosis in a major coronary artery) and normal left ventricular function. AH were in sinus rhythm with normal atrioventricular and intraventricular conduction on the surface ECG. No patient was 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 evaluated. 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.