Evidence of Mast Cell Activation Disorder in Postural Tachycardia Syndrome (P1.277)

OBJECTIVE: To identify the frequency of Mast Cell Activation in patients presenting with Postural tachycardia syndrome (PoTS). BACKGROUND: Postural tachycardia syndrome (PoTS) is a common, heterogenous syndrome that results in postural lightheadedness and a multitude of other symptoms. The exaggerated postural tachycardia and various other symptoms in PoTS patients likely result from several pathophysiologically distinct mechanisms. Shibao and colleagues in 2004 reported that mast cell activation disorder (MCAD) was a potential cause of symptoms in P0TS patients with a hyperadrenergic phenotype. MCAD is characterized by abnormal mast cell mediators and an absence of mast cell proliferation (mastocytosis). Symptoms attributed to MCAD such as tachycardia, flushing, lightheadedness, headache, and diarrhea may be indistinguishable from those reported in PoTS. DESIGN/METHODS: This study involved a retrospective review of all patients evaluated in the PoTS clinic at our institution in 2013. Results of clinical, laboratory, and autonomic studies performed on these patients were reviewed. RESULTS: One-hundred seventeen patients met criteria for PoTS. Average age was 29, and 74[percnt] were female. Of these, 20[percnt] (24/117) had laboratory evidence suggestive of a MCAD. Urinary 11-beta-prostaglandin F2 levels were elevated in 50[percnt], urinary N-methylhistamine levels increase in 16[percnt], while serum tryptase was not elevated in any of the PoTs + MCAD patients. Clinical symptoms did not differ between those with MCAD and those without, and patients with MCAD were no more likely to have evidence of a hyperadrenergic phenotype. CONCLUSIONS: Laboratory evidence of MCAD is common in patients with PoTS, but did not correlate with a hyperadrenergic phenotype in this patient cohort. Further studies are necessary to identify significance, pathophysiologic mechanisms, and potential therapeutic targets. Study Supported by:

Disclosure: Dr. Hoffman-Snyder has nothing to disclose. Dr. Lewis has nothing to disclose. Dr. Harris has received personal compensation for activities with Forest Laboratories, Ironwood Pharmaceuticals Inc., and Salix Pharmaceuticals, Inc. as an advisory board member. Dr. Dhawan has nothing to disclose. Dr. Goodman has nothing to disclose.