Year: 2001
Type: article
Abstract: II Oddział Wewnętrzny o Profilu Kardiologicznym Szpitala św. Anny w Miechowie Estimation of QT dispersion and QT variability in patients treated with coronary angioplasty Introduction: QT interval (QT) is a non-invasive measure of ventricular repolarisation. On standard electrocardiogram (ECG) the QT interval shows interlead variability called QT dispersion (dQT). In addition the QT interval is known to show circadian variation. We tested the hypothesis that successful percutaneous transluminal coronary angioplasty (PTCA) may affect rate-corrected dQT (dQT c ) and rate-corrected QT variability (QT c variability).Material and methods: We examined 30 patients (27 men and 3 women) mean age 51 ± 7, who underwent successful PTCA.Standard 12-lead ECG and 24-hour Holter ECG recordings, (both at 25 mm/s speed), were obtained from each subject before and 14 days after PTCA.The QT interval was manually measured and corrected for heart rate using Bazett's formula (QT c ). QT c dispersion (dQT c ) was defined as the difference between maximal and minimal QT c in standard ECG leads.Circadian QT c variability was defined by the difference between maximal and minimal QT c measured every hour in modified V5 lead in Holter recordings (QT c variability, zmQT c ) and by the QT c variability index (IxQT c ). IxQT c was taken as the QT c variability divided by the mean QT c value.Circadian QT c variability was assessed for the whole 24-hour period (zmQT c , IxQT c ), for the day-time, 8.00 AM-8.00 PM (zmQT c d, IxQT c d) and for the night-time, 0.00 PM-6:00 AM (zmQT c n, IxQT c n). Student t-test was used for statistical analysis.Results: There was a significant decrease of dQTc after coronary angioplasty, from 48.7 ± 16.3 ms to 35.3 ± 17.3 ms (p < 0.001).There was also a decrease in the parameters of QTc variability, but it did not reach statistical significance.In particular, the 24-hour QTc variability decreased from 66.3 ± 19.5ms to 58.9 ± 20 ms (p = 0.06) and 24-hour QTc variability index was reduced from 0.157 ± 0.049 to 0.138 ± 0.047 (p > 0.1).In addition, zmQTcd decreased from 51 ± 20 ms to 48.5 ± 14 ms (p = 0.06) and IxQTcd decreased from 0. 124 ± 0.057 to 0.114 ± 0.035 (p > 0.1).Similarly, zmQTcn was reduced not significantly from 41 ± 21 ms to 39 ± 25 ms (p > 0.1) and IxQTcn from 0.095 ± 0.046 to 0.091 ± 0.089 (p > 0.1).Conclusions: In patients with coronary artery disease successful PTCA leads to a significant decrease of QTc dispersion; however, the temporal QTc variability is not influenced significantly by PTCA.
Language: Polish
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2318116411