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

Conditions

• Stroke
• Cerebral Infarction
• Cardiovascular Diseases
• Vascular Diseases
• Atherosclerosis
• Ischemia
• Thrombosis
• Acute Coronary Syndrome

Interventions

DRUG

Aspirin (platelet sensitive versus platelet hyperreactivity)

The dose of aspirin to be prescribed in this study will be 300 mg orally or by nasogastric tube once a day (assisted therapy), with first dose tomography soon after admission if the patient has no indication of thrombolytic therapy. After the acute phase, patients will receive aspirin at a dose of 200 mg/day. Aspirin will be administered in a "simple" preparation (no buffer, no extended release).

Sponsors & Collaborators

• Fundação de Amparo à Pesquisa do Estado de São Paulo

  collaborator OTHER_GOV

• Accumetrics, Inc.

  collaborator INDUSTRY

• Helena Laboratories Point of Care

  collaborator UNKNOWN

• Chrono-Log Corporation

  collaborator UNKNOWN

• University of Sao Paulo

  lead OTHER

Principal Investigators

• Herlon S Martins, MD · University of Sao Paulo, Hospital das Clinicas, Department of Emergency Medicine

• Irineu T Velasco, PHD · University of Sao Paulo, Hospital das Clínicas, Department of Emergency Medicine

• Élbio A D'Amico, PHD · University of Sao Paulo, Hospital das Clínicas, Department of Hematology

• Tânia RF Rocha, PHD · University of Sao Paulo, Hospital das Clínicas, Department of Hematology

• Moacyr RC Nobre, PHD · University of Sao Paulo, Unidade de Epidemiologia Clínica

• Luíz R Comerlatti, MD · University of Sao Paulo, Hospital das Clínicas, Department of Neurology

• Cláudia C Leite, PHD · University of Sao Paulo, Hospital das Clínicas, Department of Radiology

• José L Andrade, MD · University of Sao Paulo, Hospital das Clínicas, Department of Radiology

Study Design

Allocation

RANDOMIZED

Purpose

DIAGNOSTIC

Masking

QUADRUPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2009-07-31

Primary Completion

2013-06-30

Completion

2013-06-30

Countries

• Brazil

Study Locations