Effects of Obstructive Sleep Apnea and Its Treatment on Signal-Averaged P-Wave Duration in Men
This study explored two questions: 1) Is there a dose-response relationship between the severity of obstructive sleep apnea (OSA) and atrial conduction, and 2) does OSA treatment affect atrial conduction?
A total of 80 consecutive male patients in sinus rhythm were enrolled from a single sleep laboratory from January to October 2010. Excluded were men with a history of atrial fibrillation, heart failure, paced rhythm, need for dialysis, and significant valvular or ischemic heart disease. OSA was diagnosed by a laboratory-based polysomnogram. Severity of OSA was determined by the apnea-hypopnea index (AHI). The signal-averaged P-wave duration (SAPWD) was calculated on the same day as the sleep study. Subjects diagnosed with AHI >15 events/hour (moderate and severe OSA) were treated with continuous positive airway pressure (CPAP) and after 1 month of CPAP, SAPWD was repeated. Comparison of SAPWD was made to 18 controls with moderate to severe OSA without CPAP.
Subjects were generally middle-aged and only slightly overweight. Among the 80 participants, 18 (23%) had no or mild OSA, 22 (28%) had moderate OSA, and 40 (50%) had severe OSA. Of those, 53% had hypertension, 10% had diabetes mellitus, 44% had dyslipidemia, 20% were current smokers, and 31% had a habit of heavy alcohol drinking. No significant change in SAPWD was found among controls between baseline and 1-month measurements. However, SAPWD was significantly shortened after 1 month of CPAP therapy (from 137.5 ± 8.6 to 129.7 ± 8.5 ms, p < 0.001), and the SAPWD change was significantly different in patients with CPAP therapy compared with controls (p < 0.001). In addition, the SAPWD change in patients with CPAP therapy correlated inversely with nightly CPAP usage (r = -0.52, p < 0.001). The average hours of CPAP usage were 4.6 ± 1.3 hours/night during this study.
The authors concluded that OSA severity was significantly associated with prolonged SAPWD, and CPAP therapy significantly shortened SAPWD in patients with moderate-to-severe OSA.
These findings suggest that there is a cause-and-effect relationship between OSA and prolonged SAPWD. This was further supported by the observed correlation between nightly CPAP usage and SAPWD. Since SAPWD has been shown to be a predictor of the development of atrial fibrillation, this study provides insight into the possible relationship between atrial arrhythmias and OSA. It remains to be shown whether effects of long-term CPAP can prevent atrial arrhythmias in men with moderate-to-severe OSA.
Keywords: Myocardial Ischemia, Undecylenic Acids, Overweight, Ethanol, Renal Dialysis, Dyslipidemias, Middle Aged, Heart Failure, Continuous Positive Airway Pressure, Hypertension, Sleep Apnea, Obstructive, Diabetes Mellitus, Ethanolamines
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