Background: QT dispersion (defined as maximal QT interval minus minimal QT interval), as assessed using the surface ECG, has been shown to reflect regional inhomogeneities in ventricular repolarization. The aim of this study was to show the effect of coronary revascularization, by successful coronary angioplasty or stent implantation, on QT dispersion.
Methods: QT dispersion was defined on each ECG as the difference between the maximal and minimal measurements of QT interval. Of 135 patients studied, 52 patients underwent coronary angioplasty and 84 patients underwent stent implantation. Maximum and minimal QT interval and QT dispersion were measured using 12-lead electrocardiography before and 24 h after each successful procedure.
Results: QT dispersion decreased from 51 +/- 12 ms at baseline to 37 +/- 10 ms 24 after the procedure (P < 0.001). Before the procedure, the QT dispersion of patients undergoing angioplasty and stent implantation was 50 +/- 13 and 52 +/- 10 ms, respectively. After the procedure, the QT dispersions were 34 +/- 9 and 38 +/- 10 ms, respectively (P < 0.001). QT dispersion was significantly lower in both groups after the procedure. No differences were observed between the QT dispersions of patients undergoing angioplasty and of those undergoing stent implantation.
Conclusions: Successful coronary angioplasty and stent implantation significantly reduced QT dispersion. The decreased QT dispersion may have been caused by improvements in myocardial perfusion and may be beneficial in reducing the likelihood of arrhythmias occurring.