Is Snoring a Risk Factor for Death?
Abstract & Commentary
Synopsis: About 18% (8/45) of patients with obstructive sleep apnea have pathologically significant cardiac rhythm disturbances. In all but one instance, these arrhythias were reversible with continuous positive airway pressure.
Source: Harbison J, et al. Chest 2000;118:591-595.
In this prospective study, harbison and colleagues applied 18-hour holter monitors to 45 consecutive patients (41 men) with fairly severe (mean apnea + hypopnea index [AHI] 50 events/h) before and after institution of continuous positive airway pressure (CPAP). Thirty-five of these patients had some nocturnal rhythm disturbance. Eight of these patients had cardiac arrhythmias that were considered to be pathologically significant. These included sinus pauses of 2 to 10 seconds in six patients, frequent premature ventricular contractions (PVCs) in two patients (1 had bigeminy, 1 had 2 salvos of 3 PVCs), and second-degree atrioventricular block (AV block) in one patient. (Some patients have more than 1 rhythm disturbance). All of these rhythm disturbances occurred between 11 pm and 7 am. After institution of CPAP, holter monitoring was repeated. Only one of these eight patients had persistent cardiac arrhythmias. This patient has ischemic cardiomyopathy and aortic stenosis, and required aortic valve replacement. Harbison et al found a significant relationship between the severity of sleep-disordered breathing and the presence of significant arrhythmia.
Comment by Barbara A. Phillips, MD, MSPH
For most of us, sleep is a time during which cardiac risk and all-cause mortality is low. Cardiac arrhythmias, blood pressure, and mortality rate tend to decline from midnight to 6 am, only to rise again coincidentally with waking from sleep.1 For healthy people, sleep reduces arrythmogenicity and cardiac risk.2 However, some individuals do not experience the relative respite from risk that sleep affords the healthy. We have known for a long time that people with sleep-disordered breathing have shorter life expectancies and that CPAP reverses that risk.3 Studies in this area have been sullied by failure to control for obesity, which also shortens life expectancy.4 In the last year, sleep apnea has clearly been shown to cause hypertension in a dose-dependent way,5-8 controlling for obesity, age, gender, and other significant risk factors. The current article adds to the body of literature9,10 that suggests that people with sleep-disordered breathing are acutely at risk to die during sleep from cardiac arryhthmias. Further, it demonstrates that CPAP apparently reverses the risk of cardiac arrhythmia during sleep in patients with sleep apnea.
For the practicing internist, the bottom line may be to consider the possibility of obstructive sleep apnea in patients with otherwise unexplained nocturnal cardiac arrythmias or symptoms of arrhythmias. v
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