Effect of mechanical coronary reperfusion on QT dispersion in acute coronary syndrome

The time for cardiac repolarization and homogeneity of repolarization on surface electrocardiogram is denoted by QT interval and QT dispersion, respectively. Numerous studies suggest an association between an increased dispersion of the QT interval obtained from the 12-lead electrocardiogram and increased risk for serious cardiac events.

We evaluated the effect of thrombolysis and percutaneous transluminal coronary angioplasty on QT dispersion in acute coronary syndrome in 45 patients (age: 55 +/- 6 years). QT dispersion was calculated on admission and immediately after the procedure (thrombolysis and percutaneous transluminal coronary angioplasty). There was a significant decrease in QT dispersion after percutaneous transluminal coronary angioplasty (75 +/- 21 ms to 38 +/- 20 ms, p < 0.0001). In a subset of these patients with acute myocardial infarction (n = 29) who underwent thrombolysis, QT dispersion decreased only marginally (78 +/- 19 ms to 67 +/- 22 ms, p < 0.05). Even in this subgroup, there was a significant decrease in QT dispersion after percutaneous transluminal coronary angioplasty (to 37 +/- 22 ms, p < 0.0001). In patients with unstable angina (n = 16), there were similar significant changes after percutaneous transluminal coronary angioplasty (p < 0.0001).

These results suggest a highly significant decrease in QT dispersion after percutaneous transluminal coronary angioplasty compared to a less significant decrease after thrombolysis, which may have clinical implications.