Prevalence and Impact of Patent Foramen Ovale in Patients with Obstructive Sleep Apnea

Background: It is well known that obstructive sleep apnea (OSA) prevalence increases as body mass index (BMI) increases. Patients with OSA experience nocturnal apnea episodes which can result in hypoxemia, transient elevation of right atrial pressures, and a possible increase in right to left shunting. As such, OSA diagnosis and therapy may be tailored to address right-to-left shunting in these patients. Whether the prevalence of PFO in OSA patients is or is not increased, it may be appropriate to include transthoracic echocardiography (TTE) testing as a component of routine evaluation of patients with OSA.

Objectives: We hypothesize that patients with hypoxemia related to OSA are more likely to have a PFO than those patients with OSA without hypoxemia.

Methods: 80 patients with OSA verified by 4 different criteria were referred for TTE by the UNM Sleep Center. All patients underwent saline contrast TTE. The prevalence of PFO in our general echo population was calculated over the last year for comparison.

Results: Of 80 patients with varying degrees of OSA, ten (12.5%) had right to left shunting. PFO was not statistically associated with any AHI (Apnea Hypopnea Index). The only statistically significant association was between OSA and BMI (p<0.001). The prevalence of PFO in the control group was found to be 12.2%.

Conclusions: In contrast to previous studies, there was no association between OSA of any severity and PFO in our study population. There however was a statistically significant association between OSA and BMI.

Abbreviations: PFO: Patent Foramen Ovale; OSA: Obstructive Sleep Apnea; TTE: Transthoracic Echocardiogram; BMI: Body Mass Index; AHI: Apnea Hypopnea Index