Effectiveness of anagrelide in the treatment of symptomatic patients with essential thrombocythemia

We prospectively evaluated the effect of anagrelide on platelet counts and the clinical manifestations of microvascular circulation disturbances in 17 newly diagnosed patients with essential thrombocythcmia. Ten patients had symptoms related to thrombacythemia, eight at the time of starting anagreli de treatment. The platelet counts before anagrelide treatment and during ma intained remission of essential thrombocythemia by anagrelide were 980 (ran ge, 610-2030) and 378 (range, 212-546) x 10(9)/L, respectively. Spontaneous platelet aggregation was found in 6 patients (35%), which disappeared on r emission of essential thrombocythemia in five cases (P = 0.02). Essential t hrombocythemia-related microvascular thrombotic and hemorrhagic symptoms di sappeared with the normalization of platelet count in all cases during main tained remission of essential thrombocythemia by long term continuous anagr elide treatment with a follow-up period of between 2 and 6 years. However, ET-related symptoms reappeared in three patients, coinciding with increased platelet count up to 600 x 10(9)/L caused by anagrelide dose reduction. We conclude that reduction of increased platelet to normal (< 400 x 10(9)n) i n symptomatic patients with essential thrombocythemia through use of mainta ined anagrelide treatment is associated with the disappearance of spontaneo us platelet aggregation and the complete relief of thrombotic and hemorrhag ic manifestations.