Essential thrombocythemia (ET) and
polycythemia vera (PV) are myeloproliferative
neoplasms (MPN) with an increased risk of arterial and
venous thrombosis.
Aspirin is recommended to reduce this risk, but resistance to antiplatelet
therapy seems to hamper its efficacy in some patients. We have previously shown that multiple
electrode aggregometry (MEA) was a valuable tool to assess
aspirin resistance in MPN. In this study, MEA was used to assess the reduction in
aspirin resistance after bi-daily (BID)
aspirin intake or cytoreduction. Fifty one MPN patients (31 ET and 20 PV) receiving 75 mg
aspirin once daily (OD) or BID, with or without cytoreductive treatment, were analyzed.
Aspirin resistance was assessed using whole blood MEA (Multiplate®, Roche Diagnostics, Meylan, France). In all patients, global
aspirin resistance consisted mainly of turnover resistance (TOR). 94% of patients with OD
aspirin intake and without cytoreduction displayed biological
aspirin resistance. By switching to a BID
aspirin regimen, the proportion of resistant patients reduced to 47%. Cytoreduction also contributed to reduce
aspirin resistance in a similar way (50% of
aspirin resistant patients). Combining cytoreduction and BID
aspirin regimen was the most efficient way to reduce
aspirin resistance yielding to 12% resistant patients. Moreover, a nonlinear correlation was observed between TOR and naive platelet counts regardless of
aspirin regimen. Last, mutational status did not seem to affect TOR. This study confirmed that BID
aspirin is biologically more effective than OD
aspirin in reduction of
aspirin resistance. The latter was achieved through a reduction in TOR which was also decreased by cytoreductive
therapy.