Effect of intracoronary balloon inflation at percutaneous transluminal coronary angioplasty on QT dispersion

Background QT dispersion (QTd) has recently been used as a marker for arrhythmic death caused by adverse drug effect. However, the effect of acute ischemia on QTd is not well described. Methods To determine the effect of acute ischemia on QTd, 12-lead electrocardiograms were obtained at baseline and 2 minutes after intracoronary balloon inflation in 34 patients. QTd was calculated as a range between shortest (QTmin) and longest (QTmax) QT intervals. Results In 18 patients balloon inflation provoked ST elevation, increased QTd (43 +/- 20 msec to 61 +/- 19 msec, p = 0.012), and decreased QTmin (390 +/- 43 msec to 361 +/- 43 msec, p < 0.001) without significant effect on QTmax (433 +/- 42 msec to 423 +/- 47 msec). No significant changes in QT measures were observed in eight patients who had ST depression and in eight without ST changes. Conclusion Acute transmural ischemia provoked by intracoronary balloon inflation increases QTd by reducing the QTmin interval, which may modify the electrophysiologic substrate.