Undiagnosed Systemic Mastocytosis Causing Recurrent Syncope and PEA Arrests

Abstract

A 72-year-old male with hypertension, pruritus, and occasional reflux reported long-standing unexplained syncope. Stress echocardiography demonstrated inducible anterior hypokinesis, and he underwent percutaneous coronary intervention for an 80% stenosis of the left anterior descending artery. Thirty minutes post-procedure, he experienced a pulseless electrical activity (PEA) arrest without ECG changes. CPR was performed with a mechanical device for 90 minutes. Urgent repeat angiography demonstrated profound coronary artery spasm; the LCx and LAD were ballooned, and nitrates and adrenaline administered. Anaphylaxis was considered the likely diagnosis. Our patient recovered and was well for three days, when a second unexplained PEA arrest occurred. Elevated serial event and basal tryptases led to suspicion of systemic mastocytosis as the underlying diagnosis. Bone marrow biopsy revealed a hypercellular bone marrow with increased mast cells on tryptase stain, and cytogenetics demonstrated positive D816V c-KIT mutation. Our patient commenced sodium cromoglycate, cetirizine, and ranitidine. His admission was significantly prolonged by multi-organ complications of his cardiac arrests. He was ultimately discharged home on day 56 post-arrest, has made an excellent functional recovery and had no further episodes of syncope at nine months post-discharge. Systemic mastocytosis is the pathological accumulation of mast cells in organs. It is a recognised cause of life-threatening syncope and PEA arrests, and estimated to affect 1 in 10,000 people. Stressors such as coronary angiography may precipitate mass mast cell degranulation and cardiac arrest. In the setting of unexplained cardiac arrest, tryptase levels should be measured and systemic mastocytosis considered as a diagnosis.