Platelet Hyperreactivity to Aspirin and Stroke

Summary

STUDY QUESTIONS * What is the real prevalence of platelet "resistance" to aspirin during the acute phase of stroke and after 3 months, and 1 year, as measured using different platelet function tests? * Do all methods measure similar levels of resistance, or are some methods more sensitive than others? * Does this resistance result in a worse clinical prognosis? Is this result independent of other variables? OBJECTIVES 1. Hospital Phase (Acute Stroke) * Determination, using various methods, of the prevalence of platelet hyperreactivity in patients treated with aspirin to treat ischemic stroke (acute phase) * Comparison of different assessment methods and identification of the most accurate of these * Identification of variables that correlate with platelet hyperreactivity 2. Follow-up Phase * Correlation between platelet hyperreactivity and important clinical outcomes at 12, 24, and 36 months * Correlation between platelet hyperreactivity and death or dependency at hospital discharge, at 3, 12, 24, and 36 months (Modified Rankin Scale) * Correlation between platelet hyperreactivity and recurrent stroke of any type * Correlation between different methods for evaluating platelet functions and identification of the most accurate method * Analysis of hyperreactivity over time THE STUDY * The study will include 200 consecutive patients seen in the emergency department of a large, urban hospital (1500 inpatient beds) and diagnosed with stroke in the acute phase; these patients will be treated with aspirin for an undetermined period * The investigators will not include patients who require full anticoagulation treatment, regardless of the cause * Importantly, the analysis of primary and secondary outcomes will be carried out after blinding the examiner to the results of the platelet aggregation tests PLATELET TESTS * Whole Blood Aggregometer, ChronoLog * VerifyNow, Accumetrics * PFA-100, Siemens * Plateletworks, Helena * Impact-R, Diamed * Serum thromboxane B2

Timeline

Start

2009-07

Primary completion

2013-06

Completion

2013-06

Drugs

Indications