Introduction: Platypnea-Orthodeoxia syndrome is characterized by dyspnea and hypoxia in the upright position, usually improving in the supine position. Two components are required: an interatrial or intrapulmonary shunt, and a functional component. Diagnosis is made by contrast ultrasonography. We report a case of Platypnea-Orthodeoxia syndrome revealed by positional dyspnea in an 87-year-old patient. The aim of this study is to describe the clinical, therapeutic and evolutionary profile of this syndrome. Case Presentation: This is an 87-year-old patient with a history of pulmonary embolism (PE) and stroke. He was seen for dyspnea and desaturation in orthostatism, revealing a patent foramen ovale (PFO). Progression was favorable after closure of the PFO. Conclusion: Platypnea-Orthodeoxia syndrome may be presented as simple exertional dyspnea. The clinician should check for improvement in symptoms and/or oxygenation during decubitus. Definitive treatment consists of percutaneous closure of the shunt.