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.