Cardiac rhythm disorders in obstructive sleep apnea

Obstructive sleep apnea (OSA) and cardiovascular diseases (CVD) commonly co-exist because of bi-directional mechanisms (1). Observational studies have shown that OSA is independently associated with CVD (1-3) and untreated OSA is associated with increased risk of cardiac events (4-6). In addition, OSA and CVD share several risk factors, including increasing age, sedentary life, and obesity, which help to explain the co-existence of both conditions in the same individuals. OSA is frequent in the general population, but it is strikingly common among patients with established hypertension (>30%) (7-9), heart failure (HF) (~40%) (10-12), and arrhythmias (~30%) (13-15). More than three decades ago, Guilleminault and colleagues reported a case series of 400 patients with OSA who underwent 24-hour Holter EKG. The authors showed that 48% had arrhythmias and conduction disturbances during sleep (16). Non-sustained ventricular tachycardia (VT), sinus arrest, and second-degree atrioventricular conduction block were the most significant rhythm disorders (16). Furthermore, among 50 patients who were treated with tracheostomy, the arrhythmias were resolved (16). Despite this compelling early evidence, OSA still remains largely underdiagnosed among patients with CVD (17). This may be partially explained by the perceived lack of studies clearly showing a causal relationship between OSA and CVD