Corrected Interval Dispersion Research Articles

Obstructive sleep apnea is associated with increased QT corrected interval dispersion: the effects of continuous positive airway pressure.

IntroductionSevere obstructive sleep apnea is associated with increased QT corrected interval dispersion and continuous positive airway pressure is thought to improve this arrhythmogenic marker.ObjectiveThe aim of the study was to determine the decrease of ratio of cardiovascular risk in patients with obstructive sleep apnea.MethodsThe study included 65 patients with severe obstructive sleep apnea who had an apnea-hypopnea index score of >30. Each patient underwent 12-channel electrocardiogram monitoring and polysomnography. Patients with an apnea-hypopnea index score of <5 were used as the control group. The control group also underwent electrocardiogram monitoring and polysomnography testing. The QT corrected interval dispersion levels of both groups were calculated. Three months after continuous positive airway pressure treatment, electrocardiogram recordings were obtained from the 65 patients with severe obstructive sleep apnea again, and their QT corrected interval dispersion values were calculated.ResultsThere were 44 male and 21 female patients with severe obstructive sleep apnea syndrome. The age, gender, body mass index, initial saturation, minimum saturation, average saturation, and desaturation index were determined in both groups. The QT corrected intervals of the obstructive sleep apnea patients (62.48 ± 16.29 ms) were significantly higher (p = 0.001) than those of the control group (29.72 ± 6.30 ms). There were statistically significant differences between the QT corrected values before and after the continuous positive airway pressure treatment, with pretreatment QT corrected intervals of 62.48 ± 16.29 ms and 3-month post-treatment values of 41.42 ± 16.96 ms (p = 0.001). There was a positive and significant correlation between QT corrected interval dispersion periods and the apnea-hypopnea index and hypopnea index in obstructive sleep apnea patients (p = 0.001; r = 0.71; p = 0.001; r = 0.679, respectively).ConclusionContinuous positive airway pressure treatment reduced the QT corrected interval dispersion in patients with severe obstructive sleep apnea. In addition, shortening the QT corrected interval dispersion periods in patients with severe obstructive sleep apnea may reduce their risk of arrhythmias and cardiovascular disease.

Effect of CPAP on QT interval dispersion in obstructive sleep apnea patients without hypertension

Objectives Delayed cardiac repolarization leading to prolongation of the QT interval is a well-characterised precursor of arrhythmias. Obstructive sleep apnea (OSA) might cause arryhthmias, since QT corrected interval dispersion (QTcd) is increased in these patients. We aimed to determine the effect of nasal continuous positive airway pressure (CPAP) therapy on QTcd in OSA patients without hypertension. Methods An overnight polysomnography (PSG) and a standard 12-lead electrocardiogram (ECG) were performed on 49 subjects without hypertension, diabetes mellitus, cardiac or pulmonary disease or any hormonal, hepatic, renal or electrolyte disorders. In 29 moderate-severe OSA (apnea–hypopnea index: AHI ⩾ 15) patients, QTd (defined as the difference between the maximum and minimum QT interval) and QTcd were calculated using the Bazzet formula at baseline and after six months of CPAP therapy. Results Eighteen patients were compliant with nasal CPAP, and mean age was 46.5 ± 4.9 years. Patients had high body mass index (BMI: 30.6 ± 4.0 kg/m 2), but there was no change in either BMI or blood pressure after six months. A strong positive correlation was shown between QTcd and AHI ( p < 0.001, r = 0.913). The QTcd at baseline (54.5 ± 8.7 ms) significantly decreased after CPAP therapy (35.5 ± 4.2 ms, p < 0.001), although it did not significantly change in 11 non-compliant patients. Conclusion In OSA patients without hypertension, CPAP therapy improves the inhomogeneity of repolarization via a significant decrease in QTcd.