Abstract Disclosure: C.G. Rivas Pajuelo: None. Introduction Pheochromocytoma (PCC) can be associated with certain genetic syndromes such as Neurofibromatosis type 1(NF1). About 5-7% of patients with NF1 will develop PCC/PGL in their lifetime. Typically, PCC presents with hypertension, and rarely, as stress-induced cardiomyopathy. Herein we present a case of a patient with NF1, and stress-induced cardiomyopathy due to Pheochromocytoma. Case presentation: A 63-year-old woman with medical history of NF1 presented to the hospital for acute hypoxemic respiratory failure and hypertensive emergency. On admission, had troponin level 27 ng/L, pro-BNP 2446 pg/ml; had a transthoracic echocardiogram (TTE) that showed EF of 30%, with global hypokinesis, anteroseptal and inferoseptal akinesis. Given NF1 history and hypertension, a CT chest/abdomen/pelvis was ordered and showed bilateral adrenal adenomas; a 2.6 cm left adrenal adenoma HFU 3, and a right adrenal mass 4.0 x 3.7 cm HFU 45 with indeterminate density. Biochemically, had markedly elevated plasma catecholamines (epinephrine 352 pg/mL, Norepinephrine 1904 pg/mL) and urinary metanephrines (2155 mcg/24 h). She markedly improved after IV diuresis, and prior to discharge was started on alpha-blockade with prazosin. This was titrated as outpatient, with addition of metoprolol 1 week later. MIBG showed intense tracer uptake in the right adrenal gland suggestive of pheochromocytoma, the left adrenal nodule was lipid rich. A repeat TTE 2 months later showed improved EF to 60% and had left heart catheterization revealing normal coronary arteries. She underwent right laparoscopic adrenalectomy, with final pathology report of 4.8 cm pheochromocytoma with negative margins. Discussion: Stress-induced cardiomyopathy is a life-threatening complication that can be the initial presentation in patients with PCC. Hypersecretion of catecholamines specifically norepinephrine and epinephrine, are thought to play a role in combination with PCC tumor cells, to act synergistically and induce direct cardiotoxic effect. Treatment with medical management followed by surgical excision of the PCC will reverse cardiomyopathy as in our patient. Ultimately, because patients with NF1 are at increased risk for PCC, it is recommended they undergo screening with plasma metanephrines and catecholamines or urinary metanephrines at least every 1-2 years especially if hypertension or tachycardia are present. Presentation: Saturday, June 17, 2023