Dual Antiplatelet Therapy in Patients With Aspirin Resistance Following Coronary Artery Bypass Grafting

August 27, 2013 updated by: University of Zagreb

Reactive platelet hyperactivity following coronary artery bypass grafting (CABG) might lead to thrombotic complications and major ischemic cardiac events. The aim of this study is to evaluate the changes in platelet reactivity following CABG and to clarify a potentially beneficial effect of dual antiplatelet therapy in the group of patients with documented aspirin resistance following CABG. Platelet function will be assessed by multiple electrode aggregometry. Aortocoronary vein graft disease is comprised of three distinct but interrelated pathological processes: thrombosis, intimal hyperplasia and atherosclerosis. Early vein thrombosis is a major cause of vein graft attrition during the first month after CABG.

Bypass patency can be improved with antiplatelet therapy which is the mainstay of treatment for patients after CABG. A beneficial effect of acetylsalicylic acid (ASA) on vein graft patency has been previously shown. Some patients experience thrombotic events despite continuous aspirin administration after CABG. The investigators hypothesized that low responsiveness to aspirin might be a precipitating factor for adverse thrombotic events following CABG.

Low responsiveness to ASA, as assessed by platelet function tests, varies widely among patients. The etiology of postoperative platelet hyperactivity remains to be elucidated.

In this study a new point-of-care assay named multiple electrode aggregometry (MEA) using a device called Multiplate analyzer (Dynabyte, Munich, Germany) has been utilized. It allows for rapid and standardized assessment of platelet function parameters.

This is a prospective randomized trial. The aim of the study is to document whether introduction of dual antiplatelet therapy in patients with ASA resistance will lead to a lower incidence of major adverse cardiac events (MACE) at a six month follow up. The composite endpoint will include death, non-fatal myocardial infarction, stroke and cardiac rehospitalization. All patients will receive 300 mg of ASA starting 6 hours after surgery, provided that the chest tube output is minimal. On postoperative day 4 their platelet function will be assessed using the above mentioned MEA. The patients found to be aspirin resistant will then undergo the process of randomization. The first arm will include patients with ASA resistance in whom no additional antiaggregation will be administered. In the second arm the investigators will include patients who were randomized to receive 75 mg of clopidogrel in addition to the standard antiplatelet regimen of 300 mg of ASA.

Platelet function monitoring allows for individual tailoring of the antiplatelet therapy. The goal of this study is to define whether this strategy will lead to improved patient outcomes. Both major and minor bleeding complications will be strictly monitored and reported.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

200

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Croatia
      • Zagreb, Croatia, 10000
        • Medical school Zagreb, University hospital center Zagreb

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Isolated coronary artery bypass grafting
  • Patients older than 18 years
  • Written informed consent
  • Accurate antiplatelet therapy administration documentation

Exclusion Criteria:

  • Missing consent
  • Patients with cardiac surgical procedures other than isolated CABG
  • Antiplatelet therapy other than aspirin 300 mg after CABG
  • Previous PCI requiring clopidogrel therapy after CABG
  • Patients with unknown preoperative anti-platelet status
  • Urgent or emergent surgery
  • Off-pump CABG
  • Re-Do CABG
  • Patients younger than 18 years

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
No Intervention: aspirin low responders monotherapy
patients with inappropriate response to aspirin assessed by multiple electrode aggregometry
Active Comparator: aspirin low responders dual antiplatelet therapy
patients with inappropriate response to aspirin 300 mg therapy after CABG, randomized to receive clopidogrel 75 mg in addition to aspirin
Drug: Clopidogrel
patients with inappropriate response to aspirin 300 mg after CABG, assessed by multiple electrode aggregometry are randomized to receive clopidogrel 75 mg daily dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
MACE events
Time Frame: 6 months
MACE: death; non-fatal myocardial infarction; stroke; cardiac rehospitalization
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Zagreb

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

June 1, 2010

Primary Completion (Actual)

February 1, 2013

Study Completion (Actual)

February 1, 2013

Study Registration Dates

First Submitted

July 8, 2010

First Submitted That Met QC Criteria

July 8, 2010

First Posted (Estimate)

July 9, 2010

Study Record Updates

Last Update Posted (Estimate)

August 28, 2013

Last Update Submitted That Met QC Criteria

August 27, 2013

Last Verified

June 1, 2010

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 8.1-10/41-2

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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