Sleep Apnea in Patients with and without a Right-to-Left Shunt.

S C I E N T I F I C I N V E S T I G AT I O N S pii: jc-00267-14 http://dx.doi.org/10.5664/jcsm.5190 Sleep Apnea in Patients with and without a Right-to-Left Shunt Mohammad Khalid Mojadidi, MD 1 ; Pooya Isaac Bokhoor, MD 1 ; Rubine Gevorgyan, MD 1 ; Nabil Noureddin, MD 1 ; W. Cameron MacLellan, MD 1 ; Eugenia Wen, MD 2 ; Ravi Aysola, MD 2 ; Jonathan M. Tobis, MD 1 Program in Interventional Cardiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA; 2 UCLA Sleep Disorder Center, University of California at Los Angeles, Los Angeles, CA Objectives: To assess the presence of right-to-left shunting (RLS) in patients with obstructive sleep apnea (OSA), and compare clinical characteristics and parameters of the sleep studies of patients with and without RLS. Background: The most common cause of RLS is due to intermittent fl ow through a patent foramen ovale (PFO). PFO occurs more frequently in patients with OSA and may be involved in the exacerbation of OSA. Methods: Patients with an abnormal polysomnogram seen at UCLA-Santa Monica Sleep Medicine Clinic were enrolled. A diagnosis of RLS was made using a transcranial Doppler (TCD) bubble study. Gender and age-matched controls were drawn from patients referred for cardiac catheterization who underwent a TCD. The frequency of RLS in OSA patients and the controls was evaluated. Clinical characteristics and polysomnogram parameters were compared between OSA patients with and without a RLS. Results: A total of 100 OSA patients and 200 controls participated in the study. The prevalence of RLS was higher in patients with OSA compared to the control group (42% versus 19%; p < 0.0001). Patients with OSA and a RLS had a lower apnea-hypopnea index (AHI), less obstructive apnea, and fewer hypopnea episodes than patients with OSA without a RLS. The baseline and nadir SpO 2 were similar in both groups and did not correlate with the level of RLS assessed by TCD. The degree of desaturation for a given respiratory disturbance, as measured by oxygen desaturation index (ODI)/AHI ratio, was higher in OSA patients with RLS versus OSA patients without RLS (0.85 ± 0.07 versus 0.68 ± 0.04; p < 0.0001). Conclusion: RLS, most commonly due to a PFO, occurs 2.2 times more frequently in OSA patients compared to a control population that was matched for age and gender. The severity of sleep apnea is not greater in OSA patients who have a PFO. However, patients with OSA and a PFO are more likely to become symptomatic at a younger age with an equivalent decrease in nocturnal SpO 2 , and have greater arterial desaturation in proportion to the frequency of respiratory disturbances. Keywords: sleep apnea, patent foramen ovale, right-to-left shunt Citation: Mojadidi MK, Bokhoor PI, Gevorgyan R, Noureddin N, MacLellan WC, Wen E, Aysola R, Tobis JM. Sleep apnea in patients with and without a right-to-left shunt. J Clin Sleep Med 2015;11(11):1299 –1304 . O bstructive sleep apnea (OSA) is an important clinical dis- order that is associated with hypertension, obesity, diabe- tes, and decreased neurocognitive performance that may lead to an increase in all-cause and cardiovascular mortality. 1,2 OSA is present in 9% of women and 24% of men and will likely increase as the population becomes more obese. 3,4 Patent fora- men ovale (PFO) occurs in 20% to 25% of the general popu- lation 5–7 ; however, recent studies indicate that PFO is present in up to 65% of patients with sleep apnea. 8,9 This higher than expected frequency of PFO with right-to-left shunting (RLS) of deoxygenated blood through the atrium suggests that sleep apnea patients with PFO may be more symptomatic or that the arterial desaturation associated with RLS may play a role in the development of sleep apnea. The aim of this study was to determine the prevalence of RLS among patients with sleep apnea and to compare clinical characteristics and the results of sleep studies of patients with and without RLS to add to the observational database of this intriguing association. BRIEF SUMMARY Current Knowledge/Study Rationale: Right-to-left shunt (RLS) oc- curs more frequently in patients with sleep apnea, and may be involved in the pathophysiology of sleep apnea. In this observational study, we determined the prevalence of RLS among patients with sleep apnea and compared clinical characteristics and the results of sleep studies of patients with and without RLS. Study Impact: Patients with OSA and RLS have hypoxemia out of pro- portion to the observed respiratory disturbance, highlighting the likely role of RLS in the resultant nocturnal desaturation. Such observational studies support the hypothesis that the presence of a RLS from a PFO may exacerbate sleep apnea symptoms METHODS The study cohort consisted of 100 people diagnosed with sleep apnea from the UCLA-Santa Monica Sleep Medicine Clinic who, by defi nition, had an abnormal polysomnogra- phy study. These symptomatic patients presented to the sleep Journal of Clinical Sleep Medicine, Vol. 11, No. 11, 2015