A 79 year old woman with permanent atrial fibrillation and New York Heart Association class II symptoms presented to our clinic for evaluation. Clinical investigation revealed a largely benign physical exam apart from an irregularly irregular heartbeat, routine laboratory studies were all within reference ranges. Subsequent transthoracic echocardiography (TTE) revealed heart failure with reduced ejection fraction (HFrEF), right ventricular systolic dysfunction, and a severely dilated right atrium. There was evidence of an atrial septal shunt (Fig. 1), however agitated saline or contrast was not preformed. Etiology of HFrEF at this time was believed to be caused by long standing atrial fibrillation, invasive angiography was offered and declined. Following image, review HFrEF guideline directed therapy (GDT) was initiated. Patient underwent repeat evaluations at regular intervals for therapy monitoring and medication titration. Within six weeks of treatment patient's presenting symptoms had resolved. However, she reported a recent change in appearance of her lips. Within 10 minutes of standing her lips would change from flesh colored pink to blue (Fig. 2). Upon closer physical examination, with patient standing, cyanosis was also noted on her fingertips (Fig. 3). While seated the patient's peripheral capillary oxygen saturation (SpO2) was greater than 95%. Within one minute of standing her SpO2 dropped to 88%. On further questioning, the patient endorsed relatively new dyspnea upon standing and with activity preformed while standing which resolved with sitting or lying down. This complaint differed from her original presenting complaint. Prior to GDT initiation patient complained of dyspnea when supine or with extended exertional activity. As, this was a significant change in her clinical exam a repeat TTE was obtained. Repeat TTE imagining further characterized her septal shunt as a patient foramen ovale (PFO) with left-to-right shunting while supine with flow reversed to right-to-left upon standing. To further characterize the shunt, cardiac magnetic resonance image (cMRI) was obtained. Imaging confirmed a large ASD with a Qp/Qs ratio of 1.5 (Fig. 4). Subsequent, right heart catheterization was remarkable for normal cardiac output and normal pulmonary artery pressure, an oximetry run was not preformed. Patient was diagnosed with Platypnea orthodeoxia syndrome (POS). Prior to HFrEF GDT direction of patient's atrial septal shunt was from left to right, and thus patient did not experience symptoms of POS. After therapy initiation, which off loaded a percentage of left ventricular pressure, her shunt reversed flow to right to left. Essentially, iatrogenic POS. In addition to her reported symptoms, the patient's hypoxemia required intervention and she underwent percutaneous PFO repair. Following recovery from her repair procedure, she was closely examined while standing. Observation during this period did not reveal central or peripheral cyanosis, and her SpO2 remained greater than 95%. Upon subsequent follow up, patient's HFrEF symptoms remained controlled and no observed return of cyanosis. Interestingly her repeat TTE preformed after approximately 8 weeks of GDT revealed a significant improvement in her ejection fraction.