Obstructive sleep apnea is a subtype of sleep disordered breathing. In obstructive sleep apnea, there is a physical obstruction to airflow despite an adequate respiratory drive. The most common symptomatic manifestation of obstructive sleep apnea is snoring. This sleep disorder is characterized by apneas which are abnormally long pauses in breathing during sleep. In addition, abnormally low breathing rates occur and they are termed hypopneas. Obstructive sleep apnea has been associated with the development of several medical diseases including hypertension, coronary artery disease, congestive heart failure, and diabetes. We have recently discussed the finding that sleep disordered breathing is associated with increased risk of developing mild cognitive impairment and dementia. Cardiac arrhythmias have also been shown to be associated with severe obstructive sleep apnea. Researchers led by Dr. Silje K. Namtvedt have shown that even mild obstructive sleep apnea in middle aged individuals is associated with increased occurrence of cardiac arrhythmia. The results of their study were published online in The American Journal of Cardiology. The researchers recruited 486 study participants from a population-based study in Norway. The study participants underwent polysomnography to assess for obstructive sleep apnea as well as Holter monitoring for arrhythmia evaluation. Obstructive sleep apnea was diagnosed in 271 study participants. The mean nadir oxygen saturation was found to be 82% for those with obstructive sleep apnea and 89% for those without obstructive sleep apnea. Cardiac arrhythmia, measured as ventricular premature complexes, occurred at a higher rate in the study participants with obstructive sleep apnea compared to the study participants without the disorder. Even study participants with mild obstructive sleep apnea had a higher rate of cardiac arrhythmia. The researchers found that the apnea-hypopnea index (AHI) was independently associated with an increased prevalence of ventricular premature complexes. The researchers wrote, “the prevalence of ventricular premature complexes is increased in middle-aged patients with mainly mild or moderate [obstructive sleep apnea], suggesting an association between [obstructive sleep apnea] and ventricular arrhythmias even in mild [obstructive sleep apnea]… The independent association between severity of [obstructive sleep apnea], as reflected by AHI, and ventricular arrhythmias in our study indicates a possible contribution by [obstructive sleep apnea] to ventricular arrhythmias and potential mechanisms for this effect are night-time hypoxemia, increased sympathetic tone, acidosis, and alterations in intrathoracic pressure during sleep”. Thus, the results of this study show that even mild forms of obstructive sleep apnea carry an increased risk for the development of cardiac arrhythmia, and suggest that the risk for other diseases such as diabetes, hypertension, atrial fibrillation, and coronary artery disease may also be increased.
Silje K. Namtvedt et al. “Cardiac Arrhythmias in Obstructive Sleep Apnea (from the Akershus Sleep Apnea Project)” The American Journal of Cardiology article in press doi:10.1016/j.amjcard.2011.06.016