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Failure of Aspirin plus Dipyridamole To Prevent Restenosis after Carotid Endarterectomy
- Laurence A. Harker, MD;
- Eugene F. Bernstein, MD, PhD;
- Ralph B. Dilley, MD;
- Terese E. Scala, RN;
- Michael J. Sise, MD;
- Robert J. Hye, MD;
- Shirley M. Otis, MD;
- Robin S. Roberts, MT; and
- Gent Michael, DSc
Abstract
▪ Objective: To evaluate therapy with aspirin plus dipyridamole in reducing restenosis after carotid endarterectomy.
▪ Patients: A total of 163 patients having 175 surgical carotid endarterectomies.
▪ Intervention: Eighty-three patients (90 endarterectomies) were randomly assigned to receive oral aspirin, 325 mg, plus dipyridamole, 75 mg, beginning 12 hours preoperatively, followed by a second dose administered within 8 hours after the operation, and given three times daily thereafter for 1 year. Eighty patients (85 endarterectomies) received placebo medication that was identical in appearance to the study drugs.
▪ Measurements: After the adequacy of the surgical procedure was confirmed by intraoperative angiography, restenosis at the endarterectomy sites was evaluated using serial duplex ultrasound studies before hospital discharge and at 3-month intervals postoperatively for 1 year.
▪ Results: Based on the time for developing identifiable restenosis and on efficacy analysis, > 50% restenosis developed in 11 operated vessels (16%) in the treated group and in 10 arteries (14%) in the placebo group, yielding an observed risk increase of 14% (95% Cl, -52% to 167%; P> 0.2). By intention-to-treat analysis, > 50% restenosis developed in 16 of 90 operated vessels in treated patients and in 10 of 85 arteries in patients receiving placebo (26% for the treated group and 12% for the placebo group; P = 0.18, Mantel-Haenszel statistic), representing an observed risk increase of 110% (Cl, -5% to 365%). Similar differences were observed for > 20% restenosis and for the comparison of patients rather than operated vessels by either intention-to-treat or efficacy analyses.
▪ Conclusions: Because therapy not only failed to reduce carotid restenosis but may have actually increased its frequency, treatment with aspirin plus dipyridamole probably has no clinically important benefit on restenosis in patients having carotid endarterectomy.
Article and Author Information
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From Scripps Clinic and Research Foundation, La Jolla, California; Emory University School of Medicine, Atlanta, Georgia; Naval Hospital of San Diego and the University of California, San Diego, California; and McMaster University and Hamilton Civic Hospitals Research Centre, Hamilton, Ontario. For current author addresses, see end of text.
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The opinions or assertions expressed herein are those of the authors and are not to be construed as official or as reflecting the views of the Navy Department or the Naval Services at large.
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Requests for Reprints: Laurence A. Harker, MD, Division of Hematology and Oncology, Emory University School of Medicine, P.O. Drawer AR, Atlanta, GA 30322.
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Current Author Addresses: Dr. Harker: Division of Hematology and Oncology, Emory University School of Medicine, P.O. Drawer AR, Atlanta, GA 30322.
Drs. Otis, Bernstein, and Dilley, and Ms. Scala: Scripps Clinic, 10666 North Torrey Pines Road, La Jolla, CA 92037.
Dr. Sise: Division of Vascular Surgery, Naval Hospital San Diego, San Diego, CA 92134-5000.
Dr. Hye: UCSD Medical Center, 225 Dickinson Street, #8401, San Diego, CA 92103-8401.
Dr. Gent and Mr. Roberts: Hamilton Civic Hospitals Research Centre, 711 Concession Street, Hamilton, Ontario, L8V 1C3, Canada.
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