Abstract Background Platypnea-orthodeoxia syndrome (POS) is a rare but treatable cause of positional hypoxemia, typically associated with intracardiac shunting. We present the first documented case of POS secondary to patent foramen ovale (PFO) in a patient with right-dominant arrhythmogenic cardiomyopathy (ACM). Case Summary A 48-year-old male with right-dominant ACM developed progressive dyspnea and upright hypoxemia. Workup examinations revealed atrial flutter and PFO with right-to-left shunting. PFO occlusion resolved hypoxemia, with sustained improvement at 3-year follow-up despite progressive RV dysfunction. Discussion This case represents a rare form of POS attributable to the coexistence of PFO and right-dominant ACM. The pathophysiological mechanism underlying POS in this case might be parallel to that observed in right ventricular myocardial infarction or ischemia in which elevated right-sided intracardiac pressures due to impaired RV output secondary to right heart dysfunction equals or surpasses left heart pressure which created a pressure gradient favorable for right-to-left shunting (RLS) through the PFO in upright position. Based on comprehensive clinical evaluation, PFO closure was ultimately performed. Conclusion This case highlights right-dominant ACM as a novel predisposing factor for POS via PFO shunting. The pathophysiological mechanism underlying POS in this case might be parallel to that observed in right ventricular myocardial infarction or ischemia. PFO closure may be curative for right-dominant ACM-related hypoxemia and POS.
Peng et al. (Sat,) studied this question.