Platelet-mediated thrombotic complications in patients with ET: Reversal by aspirin, platelet reduction, and not by coumadin.

The broad spectrum of aspirin-sensitive erythromelalgia, its microvascular ischemic complications, migraine-like atypical or typical transient ischemic attacks (cerebral and ocular) as well as acute coronary syndromes in thrombocythemia vera (essential thrombocythemia and thrombocythemia associated with polycythemia vera in maintained remission by phlebotomy) is caused by platelet cyclo-oxygenase-mediated arteriolar inflammation, fibromuscular intimal proliferation without and with occlusive thrombosis by platelet-rich thrombi in the end-arterial microvasculature of the peripheral, cerebral, ocular and coronary circulation. These microvascular ischemic and thrombotic complications does not respond to Coumadin, but are immediately relieved by a loading dose of 500 mg aspirin, and does not recur when the patient is maintained on low dose aspirin (50 mg per day) or after reduction of platelet counts to normal (<400.000/microl).