Abstract 18669: Pheochromocytoma Crisis Precipitated by Carvedilol

Abstract

Description of case: Pheochromocytomas are rare, catecholamine-secreting tumors of the adrenal gland. Definitive treatment is surgical, but requires pre-operative optimization with alpha, followed by beta blockade (BB). Initial treatment with BB can precipitate pheochromocytoma crisis, characterized by hemodynamic instability and end-organ dysfunction. This case describes pheochromocytoma crisis in a young, healthy female after switching from metoprolol to carvedilol. A 27-year-old woman is evaluated by an outpatient cardiologist for recurrent palpitations, “hot flashes” and headaches. Mobile telemetry monitor reveals episodes of “SVT” for which she is started on metoprolol succinate. Given her symptoms, testing for plasma free metanephrines is ordered and is markedly abnormal. Subsequently the patient is switched from metoprolol to carvedilol. Within a few hours of taking carvedilol the patient reports sudden onset dyspnea, nausea, vomiting and chest pain. On arrival, vital signs are remarkable for a resting pulse of 130 and blood pressure of 130/97. EKG shows sinus tachycardia. Labs reveal a high-sensitivity troponin of 1,816 ng/L and a 2-hour troponin of 4,560. CT shows a 5.8 cm left adrenal mass. An echocardiogram reveals a reduced LVEF of 45-50% and is suggestive of reverse takotsubo cardiomyopathy. Her carvedilol is discontinued, she is started on prazosin and her symptoms resolve within 24 hours. She later resumes metoprolol and proceeds with surgical excision. Discussion: This case reports a pheochromocytoma crisis likely precipitated by carvedilol and complicated by reverse-takotsubo cardiomyopathy. Interestingly, the patient tolerated metoprolol despite being in the same class. This switch was made knowing she tolerated BB and with the idea that she would benefit from additional alpha-blockade. Carvedilol is a racemic mixture, with S-carvedilol binding beta-1 and -2 receptors while R-carvedilol binds strictly alpha-1. There is evidence that patients catabolize the enantiomers differentially, resulting in higher concentrations of one enantiomer in an unpredictable manner. It is therefore preferred to avoid all BB before sustained alpha blockade while treating pheochromocytoma despite the patient’s previous tolerance.