Platypnoea orthodeoxia syndrome (POS) is an uncommon condition characterised by dyspnoea and arterial desaturation induced by an upright position and relieved in the supine position, usually due to a patent foramen ovale (PFO). Percutaneous closure of a PFO is the preferred treatment to cure POS. This study aimed to evaluate the clinical and gasometrical characteristics and to describe the long-term outcomes of percutaneous PFO closure in a group of patients with POS.

Patients with POS and a PFO treated by percutaneous intervention from 2010–2020 were reviewed. The primary efficacy outcome was the arterial oxygen pressure to fraction of inspired oxygen (PaO₂/FiO₂) ratio before and 24 hours after the procedure. Total clinical success was considered if the arterial oxygen saturation measured by pulse oximetry (SpO₂) improved to >94% in the supine and sitting positions without supplemental oxygen, while partial success was considered if SpO₂ improved from baseline but still required oxygen to achieve >94%. Secondary outcomes were an absolute improvement in SpO₂ and sense of dyspnoea, without significant residual shunt on transthoracic echocardiography (TTE) at follow-up.

Of 168 patients undergoing PFO or atrial septal defect closure, 14 had POS (8.3%). Percutaneous PFO closure was successfully performed in all patients with a single device. Twelve of 14 patients had total clinical success (86%) and one patient had partial success. The PaO₂/FiO₂ ratio increased from 155.9±50.6 to 318.3±73.4 after PFO closure (p=0.002). All patients with total clinical success had a successful secondary efficacy outcome with an absolute improvement in SpO₂ and complete resolution of dyspnoea, which was maintained at follow-up (37±20 months; range, 11 months to 6 years). None had a significant residual shunt between 12 and 24 months of follow-up.

The PFO percutaneous closure was a successful, durable and safe method for patients presenting with POS; it achieved major improvements in both gasometrical parameters and quality of life.