Tp-e Interval, Tp-e/QT Ratio, and Tp-e/QTc Ratio are Prolonged in Patients with Moderate and Severe Obstructive Sleep Apnea

Background: Prolongation of the peak and the end of T wave (Tp-e) has been reported to be associated with ventricular arrhythmias. Tp-e/QT ratio and Tp-e/QTc ratio are used as an index of ventricular arrhythmogenesis. An increased incidence of ventricular arrhythmias has been reported in patients with obstructive sleep apnea (OSA). The aim of this study was to assess ventricular repolarization in patients with OSA by using Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio. Methods: We have studied 72 patients who underwent overnight polysomnography (PSG) between the years 2010-2011 at our institution. Patients with moderate and severe OSA (23 patients; mean age: 45 +/- 10), according to the apnea-hypopnea index, constituted the study group. Patients with normal PSG (23 patients; mean age: 42 +/- 11) were used as the control group. In all patients, Tp-e interval, Tp-e/QT ratio, Tp-e/QTc ratio, as well as some other electrocardiogram intervals were measured. Independent samples t-tests were used for comparison of continuous and categorical variables and correlations were calculated by Spearman rank correlation. Results: Although QT and QTc intervals were not different between the groups, mean Tp-e interval (81.6 +/- 11.1 msn; 63.9 +/- 7.3 msn; respectively; P < 0.001), Tp-e/QT ratio (0.21 +/- 0.03; 0.17 +/- 0.02; respectively; P < 0.001), and Tp-e/QTc ratio (0.20 +/- 0.03; 0.16 +/- 0.02; respectively; P < 0.001) were prolonged in the study group compared to the control group. Correlation analysis showed a significant positive correlation between the presence of moderate and severe OSA and Tp-e interval (r = 0.72; P < 0.001), Tpe/QT ratio (r = 0.70; P < 0.001), and Tp-e/QTc ratio (r = 0.70; P < 0.001). Conclusions: Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio are prolonged in patients with moderate and severe OSA patients. There is a positive correlation between the presence of OSA and Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio. (PACE 2012; 35:966-972)