Systemic Mastocytosis, Kounis Syndrome and Coronary Intervention: Case Report and Systematic Review

A 72-year-old male reported a long-standing history of unexplained syncope. Stress echocardiography demonstrated inducible anterior hypokinesis, and he proceeded to percutaneous coronary intervention for an 80% stenosis of the left anterior descending artery. Thirty minutes post-procedure, he experienced a pulseless electrical activity (PEA) cardiac arrest. Urgent repeat angiography demonstrated profound coronary artery spasm consistent with Kounis syndrome. Three days later, a second PEA arrest occurred. Systemic mastocytosis was ultimately diagnosed as the cause of his recurrent syncopal episodes and cardiac arrests. Our patient was discharged 56days after his cardiac arrest on appropriate immunotherapy, and has made an excellent event-free recovery. Systemic mastocytosis is the pathological accumulation of mast cells in organs, and it may cause life-threatening syncope and cardiac arrests. It is estimated to affect up to 1 in 10,000 people, however is often underdiagnosed. No previous reviews have examined cardiac manifestations of systemic mastocytosis. We undertook a structured systematic review of cardiac presentations of systemic mastocytosis in adults, screening 619 publications. Twenty-three cases met inclusion criteria; our review suggests that short-term mortality is high (22%), and patients with cardiac presentations are predominantly male (83%). Unexplained cardiac arrest (26%) may be the first presentation of this haematological disorder. From our review of the literature, we have also derived suggested management approaches for cardiologists encountering or suspecting systemic mastocytosis in a variety of clinical scenarios.