[QT dispersion in patients treated with repeated percutaneous transluminal coronary revascularization]

In this study the group of 30 patients with coronary artery disease (mean age 55 +/- 7 years) were examined. All patients underwent repeated percutaneous transluminal coronary revascularisation (rePTCR) due to coronary artery restenosis after primary coronary angioplasty. QT dispersion (dQT) and the corrected QT dispersion (dQTc), obtained applying Bazett's (dQTB) and Hodge's (dQTH) formulas, were measured before rePTCR and 7 days after rePTCR. Standard 12-lead electrocardiograms, 25 mm/s speed, were used. QT dispersion, defined as a difference between maximal and minimal QT intervals, was manually measured. The significant decrease of dQT after rePTCA was observed. Mean dQT before rePTCR was 88.67 +/- 29.09 ms and 64.00 +/- 28.96 ms after rePTCR (p < 0.0001). The changes of dQTc (dQTB, dQTH) were similar. Mean values of dQTB before and after rePTCR were 92.97 +/- 34.40 ms and 65.42 +/- 29.80 ms respectively, and mean values of dQTH were 94.90 ms +/- 37.31 ms and 70.98 ms +/- 32.85 ms. It was also noted that the frequency of appearance of dQT exceeding 80 ms significantly decreased after rePTCR (dQT exceeded 80 ms in 17 cases before rePTCR vs 5 cases after revascularisation). Increased QT dispersion can be a marker of the coronary artery restenosis.