Effect of Balloon Inflation-Induced Acute Ischemia on Qt Dispersion During Percutaneous Transluminal Coronary Angioplasty

Abstract

Background: QT dispersion (QTd = QT(max) - QT(min)) measured as interlead variability of QT interval reflects the spatial inhomogeneity of ventricular repolarization times, and increased QTd may provide a substrate for malignant ventricular arrhythmias. Ischemia is associated with regional abnormalities of conduction and repolarization. Hypothesis: This study aimed to investigate the effect of acute ischemia on QTd during successful percutaneous transluminal coronary angioplasty (PTCA). Methods: Forty-three patients (10 women, 33 men, mean age 56 pears) were enrolled in the study. Electrocardiogram (ECG) recordings were taken before PTCA and during balloon inflation period. QT maximum (QT(max)), QT minimum (QT(min)), and QTd(QT(max) - QT(min)) values were calculated from the surface EGG. Results: There was no difference among QT(max) values (p = 0.6). Mean QT(min) during balloon inflation was lower than before PTCA (368 +/- 45 vs. 380 +/- 31 ms, p = 0.002). The difference between QTd values before and during balloon inflation was statistically important (65 +/- 9 vs. 76 +/- 10 ms, p = 0.001). This difference is caused by a decrease in QT(min), during balloon inflation. Conclusion: Acute reversible myocardial ischemia induced by balloon inflation causes an increase in QTd value, and this increment is the result of a decrease in QT(min), interval. Therefore, QTd may be a marker of reversible myocardial ischemia.