Summary

The objective of the study was to determine the effects of nasal continuous positive airway pressure (nCPAP) therapy on left ventricular (LV) function and electrocardiographic parameters in newly diagnosed moderate/severe obstructive sleep apnea (OSA) patients without cardiovascular comorbidities and medical treatments. We examined 44 patients who underwent overnight polysomnography together with 24-hour Holter electrocardiography, cardiopulmonary exercise testing including heart rate recovery at 1 minute (HRR-1), echocardiography, surface electrocardiography, and those who were diagnosed with moderate/severe OSA apnea—hypopnea index ≥ 15. After 3 months of nCPAP treatment, the above-mentioned examinations were repeated. Forty-four patients completed the treatment period. Twelve weeks on effective nCPAP induced a significant increase in the mitral E/A ratio (P = 0.001), as well as reductions in isovolumic relaxation time (P = 0.001) and mitral deceleration time (DT) (P = 0.002). There were no significant differences in LV ejection fraction, LV mass index, and pulsed wave Doppler parameters. Mean heart rate was 79.2 ± 12.5 pulses/minute, maximum P-wave duration 117.5 ± 8.6 msec, P-wave dispersion (PWd) 54.6 ± 10.2 msec, corrected QT interval (QTc) 436.5 ± 40.5 msec, and QT dispersion (QTd) 46.3 ± 7.1 msec, which significantly decreased to 70.4 ± 9.6 pulses/minute (P < 0.001), 111.5 ± 8.7 msec (P < 0.001), 51.6 ± 8.9 msec (P < 0.001), 418.4 ± 31.2 msec (P < 0.001), and 33.8 ± 3.4 msec (P < 0.001), respectively. Exercise capacity at baseline determined as 10.5 ± 2.2 metabolic equivalents (METS) and HRR-1 (20.6 ± 11.7 bpm) significantly increased (12.1 ±1.5 METS and 27.4 ± 8.6 bpm). There was no significant difference in aortic root parameters. Three-month nCPAP therapy significantly increased LV shortening fraction, with no effect on systolic function or aortic root diameters and a positive effect on heart rate, PWd, HRR-1, QTc and QTd time following nCPAP therapy. (Int Heart J 2015; 56: 94-99) Key words: Apnea-hypopnea index, Heart rate recovery time, Left ventricular function, P-wave dispersion, QT corrected interval