Evaluation of overnight O2 therapy on QT dispersion in patients with chronic heart failure

Nocturnal hypoxia is an important factor increasing the risk of mortality in patients with chronic heart failure and is associated with atrial and ventricular arrhythmias. QT dispersion، an index of myocardial electrical activity، is used as a prognostic tool in determining future malignant arrhythmias and sudden cardiac death. In the current study we investigated the effect of nocturnal oxygen therapy (NOT) on QTd in patients with CHF. In this clinical study 54 patients with CHF (EF≤40%) were enrolled. Patients were administered NOT; electrocardiography was taken before and after NOT and QTd measured each time. Paired t-test was used to compare pre- and post-NOT QTd. QTd significantly decreased from 56. 3±18. 2 msec before NOT to 46. 3±17 msec after NOT (p=0. 001). In this study NOT decreased QTd in patients with CHF which could consequently decrease risk of malignant arrhythmias and sudden cardiac death. However، the mechanisms by which NOT decreases QTd is not clear and requires further investigation.