Platelet Hyperreactivity to Aspirin and Stroke

• Status: Completed
• Trial end date: 2013-06-01
• Target enrollment: 0
• Participant gender: All

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

• Phase: Phase 4
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: University of Sao Paulo
• Collaborators: Accumetrics, Inc.; Chrono-Log Corporation; Fundação de Amparo à Pesquisa do Estado de São Paulo; Helena Laboratories Point of Care
• Treatments: Aspirin

Criteria

Inclusion Criteria:

• Consecutive patients with the diagnosis of ischemic stroke in the acute phase who will be treated with aspirin for an indefinite period

Exclusion Criteria:

• The need for full anticoagulation therapy for pulmonary embolism, deep vein thrombosis, chronic atrial fibrillation, thrombus in the left atrium or left ventricle, or for any other reason deemed relevant by the patient's physician

• Thrombolytic treatment for stroke

• History of allergy to aspirin (hives, swelling of glottis or anaphylaxis)

• Risk of excessive bleeding due to active peptic ulcers, liver failure, history of bleeding or bleeding diathesis

• Scheduled major or vascular surgery

• Metastatic cancer or survival estimated at less than a year

• Creatinine clearance below 30 mL/min

• Platelet count <100,000/mm3

• Hematocrit <30%

• Lipaemic blood

• Difficult follow-up: patients with serious social problems, alcoholics, and residents of other states in the country

• Refusal to participate in the study