QT Interval Dispersion as a New Marker of Restenosis after Percutaneous Transluminal Coronary Angioplasty of Isolated Single-Vessel Coronary Artery Stenosis

Abstract

Background: There are no reliable non-invasive markers of restenosis after percutaneous transluminal coronary angioplasty (PTCA). The aim of our study was to measure changes in QT interval dispersion after PTCA and to determine whether restenosis subsequently affects QT interval dispersion. Methods and Results: Fifty-six consecutive patients – 41 men and 15 women (mean age: 56.2 ±8.3 years) – with isolated stenosis of the left anterior descending artery who underwent successful PTCA were studied. A symptom-limited treadmill exercise test was performed within 7 days after PTCA and then again before repeated angiography. Repeated coronary angiography revealed restenosis in 15 patients (26.8%) and no signs of significant stenosis in 41 patients (73.2%). QT interval dispersion in the group of patients with restenosis measured before exercise increased from baseline 34 ± 7 to 49 ± 15 ms after 6 months (p < 0.01) and QT interval dispersion measured immediately after exercise increased from baseline 38 ± 4 to 68 ± 21 ms after 6 months (p < 0.001). In contrast, patients without restenosis showed no significant changes in QT interval dispersion measured before (baseline: 34 ± 9 ms; after 6 months 33 ± 12 ms; p = NS) and immediately after exercise (baseline: 34 ± 12 ms; after 6 months: 33 ± 10; p = NS). When QT interval dispersion ≧60 ms (measured 6 months after PTCA procedure) was considered as a potential marker of restenosis, this indicator had very high sensitivity and specificity when measured immediately after exercise (80 and 95% respectively). Conclusions: QT interval dispersion significantly increases in the group of patients with documented restenosis and may be a simple, non-invasive marker of restenosis. However, further studies are needed to confirm this observation.