Electrocardiographic parameters of myocardial electrical instability in patien with obstructive sleep apnea-hypopnea syndrome and newly diagnosed arterial hypertension
Objective. To study the rate of long QTc and JTc intervals in sleep-wakefulness cycle, and also their relationship with severity of obstructive sleep apnea-hypopnea syndrome (OSA) in patients with newly diagnosed hypertension (HTN). Design and methods. 24-hour multifunctional monitoring was conducted in 59 male patients (age 38,0 ± 7,7 years old; body mass index 33,8 ± 5,4 kg/m <sup>2</sup>) with elevated office blood pressure, who did not receive any medications. All patients had two or more risk factors of HTN. Organ damage was identified in 12 (20 %) patients. The long QTc interval was defined as 450 msec or more, automatic analysis was performed using 8-lead dynamic ECG. Results. OSA was diagnosed in 40 (68 %) patients: 17 patients had mild sleep apnea (apnea-hypopnea index, AHI, from 5 to 14 episodes per hour), the rest of the patients had moderate and severe OSA (AHI from 18 to 97 episodes per hour). Nineteen (32 %) patients without OSA were included in the comparison group (AHI less than 5 episodes per hour). There was no differences in average heart rate during assessed time periods between the groups. There was a direct positive correlation between duration of QTc and JTc calculated separately for periods of wakefulness, sleep and AHI and hypoxemia index. Conclusions. More than 50 % of patients with newly diagnosed AH and OSA without associated cardiovascular diseases demonstrate changes in myocardial repolarization throughout sleep-wakefulness cycle. These changes are associated with the number of apneas/hypopneas and the severity of hypoxemia during sleep.