Essential thrombocytosis and myocardial infarction in an aircrew member: Aeromedical concerns

Of essential thrombocytosis (ET) cases, 25% occur in patients younger than 40 yr of age, and are often discovered as an incidental laboratory abnormality. However, the risk for thrombosis remains of concern and needs to be closely evaluated, especially in the aerospace environment. We report on the case of a 40-yr-old, female French military air traffic controller (ATC) admitted for an ST-elevation myocardial infarction. She was a smoker and had no previous medical history of ET. The coronary angiogram showed a thrombus of the left anterior descending coronary artery. She was treated medically with angioplasty and stent. Laboratory data revealed an elevated platelet count (495,000 center dot mm(-3)), confirmed 6 mo later (645,000 center dot mm(-3)). The diagnosis of ET was then established. No platelet-lowering therapy was prescribed, aspirin was continued, and this ATC was considered unfit for operational duties. Arterial thrombosis is more frequent than venous in ET, and can affect the whole arterial tree from the microscopic to the main arteries. Thrombosis is unpredictable and, due to abnormalities of the platelet functions and associated cardiovascular risk cofactors, may occur even with an almost normal platelet count. Risk-adjusted therapy is needed, including lifestyle modification to address vascular risk factors, antiplatelet drugs (aspirin), and platelet-lowering agents with their risk of leukomutagenesis. Furthermore, there is no consensus for the prevention of venous thrombosis. The decision for the aeromedical expert is difficult and depends on the specialty of the aircrew member, the type and duration of the mission, the therapeutics used, and the benefit-risk ratio of platelet-lowering agents.