Abstract 12981: Non-Conventional Causes of ST-Elevation Myocardial Infarction: Essential Thrombocytosis

Abstract

Case: A 61-year-old female with no significant past medical history, except hospitalization for COVID-19 pneumonia complicated by myocarditis ten months prior, presented to the emergency department with worsening chest pain over the last two weeks. The admission electrocardiogram (ECG) was without ischemic changes. The initial impression was that the patient's symptoms were attributed to her prior myocarditis. However, a repeat ECG obtained six hours later, due to worsening chest pain, demonstrated ST-segment elevations in leads V2, I and AVL. Emergent coronary angiography was performed, showing a 90% occlusion of the proximal LAD, which was managed with a drug-eluting stent. Admission platelet count was significantly elevated at 1,049,000mm 3 , which resulted in a hematology consultation. Her further work up included a positive JAK2-V617F mutation and negative BCR-ABL1 translocation, which confirmed the diagnosis of essential thrombocythemia. During the prior hospitalization for her COVID pneumonia, she underwent invasive coronary angiogram for suspected myocardial infarction in the setting of elevated troponin, which showed a mild, non-obstructive lesion in the proximal LAD. She underwent a cardiac MRI that demonstrated both sub-epicardial and mid-wall late gadolinium enhancement consistent with myocarditis. Discussion: Essential thrombocythemia is a clonal myeloproliferative disease caused by a pathological expansion of megakaryocytes, which results in excess platelet production. Essential thrombocythemia leads to a hematologic hyper-viscosity and subsequent increased risk of vasomotor, thrombotic and hemorrhagic manifestations. Myocardial infarction as the primary clinical presentation of essential thrombocythemia is rare but an important risk factor that should be considered in patients presenting with acute coronary syndromes and elevated platelet counts, both with and without traditional cardiovascular risk factors.