High Prevalence of Abnormal Nocturnal Oximetry in Patients With Hypertrophic Cardiomyopathy

Objectives We sought to determine the prevalence of nocturnal oxygen desaturation and obstructive sleep apnea (OSA) in a population of patients with hypertrophic cardiomyopathy (HCM). Background The coexistence of sleep apnea and HCM, 2 common cardiovascular conditions, has been largely unrecognized in the treatment of patients with HCM. The nocturnal hypoxia-induced hyperadrenergic state in OSA is expected to worsen hemodynamics and outcomes in HCM. Methods One hundred subjects with HCM between June 1, 2006, and July 14, 2008, were screened with nocturnal oximetry. Clinical variables were collected for statistical analysis. Oximetry was classified abnormal (suspicion of sleep-disordered breathing) in the presence of repetitive desaturation (>= 5 events/h) followed by a rapid return to baseline oxygen saturation (SaO(2)) level with a decrease of >= 4% and threshold of 90%. Results Seventy-one (71%) patients with HCM had abnormal nocturnal oximetry (71 +/- 9%, 95% confidence interval: 62% to 80%). Subjects with abnormal oximetry were older (age 59.5 +/- 15.3 years) and more were hypertensive (n = 39 [55%]) than those with normal oximetry (age 45.8 +/- 18.5 years, n = 9 [31%], p < 0.001, p = 0.03). Patients with HCM were more symptomatic in the presence of abnormal oximetry (New York Heart Association functional class II to III) (62% vs. 83%, p = 0.023). HCM patients had a higher prevalence of abnormal nocturnal oximetry (n = 71, 71%) compared with a control group of similar age and sex distribution (n = 49, 49%) (p = 0.001). Conclusions Abnormal nocturnal oximetry is common in patients with HCM, suggesting that OSA is prevalent. OSA may impact hemodynamics and symptoms in HCM. Further studies are needed to determine the long-term benefit of OSA treatment on hemodynamics and disease progression in HCM. (J Am Coll Cardiol 2009;54:1805-9) (c) 2009 by the American College of Cardiology Foundation