Patent Foramen Ovale and Oxygenation in Patients with Cystic Fibrosis.

Introduction: Patent foramen ovale (PFO) affects about 25% of the population. We studied outcomes in cystic fibrosis (CF).

Methods: We conducted a case-control study of patients with CF (PwCF) and age- and sex-matched controls who underwent agitated saline contrast (bubble) echocardiography, 1998-2020. We assessed PFO impacts using linear, logistic, quasi-Poisson, and Cox proportional hazards models.

Result: Fifty-nine of 64 PwCF and 88 of 93 controls underwent bubble studies to investigate unexplained hypoxemia or dyspnea. PwCF had higher mean pulmonary artery pressure (PAP: 6.9 mm Hg, 95% confidence interval [CI] = 2.35-11.4), reduced tricuspid annular plane systolic excursion (TAPSE: -3.78 mm, CI = -5.64 to -1.93) and similar right ventricular diastolic sizes. Without hypoxemia, the PFO incidence was similar between PwCF and controls; with hypoxemia, PFO was more common in CF (odds ratio = 5.00, CI = 1.32-19.0). In CF, oxygen supplementation occurred at a percent-predicted forced expiratory volume in 1 s (FEV1%), 22.5 points higher with PFO. Adjusted for FEV1%, PFO was associated with 0.59 more prior-year pulmonary exacerbations (CI = 0.20-0.98) and shorter time to next exacerbation (hazard ratio = 1.86, CI = 1.06-3.26). Associations between PFO and hypoxemia or exacerbations were insensitive to PAP, TAPSE, and CF transmembrane regulator protein modulator treatments. PFO was not associated with CF time to death or lung transplantation (median 1.87 years) adjusted for age, sex, FEV1%, and prior-year exacerbation counts.

Conclusion: PFO in CF is associated with hypoxemia at higher FEV1% and more pulmonary exacerbations but not survival.