https://www.jacc.org/doi/abs/10.1016/S0735-1097%2824%2906384-8
J Am Coll Cardiol. 2024 Apr, 83 (13_Supplement) 4394. https://doi.org/10.1016/S0735-1097(24)06384-8
Abhtnav Karan Kabeer Ali, Gerardo Diaz Garcia, Aarav Mohanlal, Zachary Chandler, Fabiana Rollini, University of Florida College of Medicine – Jacksonville, Jacksonville, FL, USA
Background: Kounis syndrome is typically associated with severe systemic allergic reactions. We describe a rare case of Kounis syndrome from mast cell degranulation from systemic mastocytosis.
Case: A 64-year-old male presented for elective stress myocardial perfusion imaging (MPI) due to exertional dyspnea. The patient was unable to achieve maximal heart rate with exercise, and the decision was made to provide regadenoson. Subsequently, 0.4mg of regadenoson was injected intravenously with the onset of sudden, severe substernal chest pain. The MPI was aborted and an electrocardiogram revealed 1.5mm ST segment elevation in leads II, III, and aVF with reciprocal ST segment depressions in V1-V3. His chest pain was resolved with sublingual nitroglycerin, however, emergent left heart catheterization revealed 80% calcified stenosis of the mid-right coronary artery (mRCA). A concern for coronary vasospasm was raised, but the patient subsequently underwent orbital atherectomy with percutaneous coronary intervention (PCI) to the mRCA. Dual antiplatelet therapy with aspirin and ticagrelor was started. In the following two months, the patient endorsed frequent complaints of pruritus following aspirin administration, and worsening pancytopenia, eventually resulting in a bone marrow biopsy which revealed systemic mastocytosis. Aspirin was discontinued with the patient remaining on ticagrelor monotherapy.
Decision-making: Our patient’s initial presentation was likely due to coronary vasospasm over a background of 80% mRCA stenosis due to mast cell degranulation following regadenoson administration, consistent with Kounis syndrome type II. PCI was pursued initially due to pre-existing mRCA stenosis, however, systemic mastocytosis was discovered later following recurrent episodes of pruritus due to recurrent mast cell activation from aspirin administration. Ticagrelor has an overall lower risk of mast cell degranulation, so the decision was made to allow ticagrelor monotherapy.
Conclusion: Systemic mastocytosis is a challenging comorbidity in patients with coronary artery disease that limits the use of antiplatelet therapy and can present as Kounis syndrome.
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