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SVS-VESS Scientific Session @ VAM: Session 1

VESS09 - Evaluation of Plavix Resistance and Its Role in Predicting Stent Thrombosis in Transcarotid Artery Revascularization

Wednesday, June 14, 2023
2:34 PM – 2:41 PM ET

    Submitting & Presenting Author(s)

  • Kathryn L. DiLosa, MD

    Resident Physician
    University of California Davis
    Sacramento, California

    • Co-Author(s)

  • JH

    Joel Harding

    Resident Physician
    University of California Davis
    Sacramento, California

  • AP

    Anjani Patibandla

    Medical Student
    University of California Davis
    Sacramento, California

  • SM

    Steven Maximus, MD

    Assistant Professor of Surgery
    University of California Davis
    Sacramento, California

    • Senior Author(s)

  • MK

    Mimmie Kwong, MD

    Assistant Professor of Surgery
    University of California Davis
    Sacramento, California

    • Discussant(s)

  • Roberto G. Aru, MD

    Vascular Surgery Clinical Fellow
    The Johns Hopkins Hospital
    Baltimore, Maryland

Objectives: While up to 70% of patients have resistance to Plavix in the coronary literature, resistance testing is not routinely performed despite its common use as an antiplatelet for prevention of stent thrombosis in Transcarotid Arterial Revascularization (TCAR) procedures. The extent to which resistance exists in patients undergoing TCAR has not been well described. We sought to compare the modalities for Plavix resistance testing and determine the prevalence of resistance and its effect on stent outcomes.

Methods: Patients undergoing TCAR at our institution between 2018-2022 were retrospectively identified. Plavix-resisting test results were recorded. Patient characteristics, perioperative details, and outcomes are described.

Results: A total of 85 patients underwent TCAR, 52 (61%) for symptomatic disease. 65 (77%) patients were on dual antiplatelet therapy (DAPT) for at least 7 days prior to TCAR. 7 (8%) patients not on DAPT were on anticoagulation prior to surgery and most (6) received a loading dose of a second antiplatelet the day of their procedure. Nine patients (10.6%) developed stent thrombosis during the follow-up period. Patients not taking DAPT for at least 7 days prior to surgery were more likely to develop stent thrombosis (30% versus 4.6%, p<.001).

Plavix resistance testing was performed in 35 (41%) patients, with 25 patients undergoing thromboelastogram (TEG) with platelet mapping, 5 undergoing VerifyNow P2Y12 inhibitor testing, and 5 undergoing testing with both modalities. Plavix resistance was noted in 24 patients (69%) using all testing results. In patients that underwent both testing modalities, agreement was poor (Cohen’s Kappa -0.05) (Table I).

Among patients with Plavix resistance, 17 (72%) did not thrombose and 5 (20%) patients did thrombose. Comparatively, 1 (9.1%) patient without resistance thrombosed (p=.161). Of the 5 patients with thrombosed stents that underwent testing, 4 were Plavix resistant (80%) (Table II). VerifyNow correctly predicted resistance and non-resistance more accurately than TEG (7 of 9 correct, 78% vs 11 of 29 correct, 38%, p=.001). VerifyNow had sensitivity of 60% and specificity of 100% for stent thrombosis.

Conclusions: Our experience demonstrates that Plavix resistance rates are high in the TCAR patient population, with higher thrombosis rates in those that test positive for resistance. VerifyNow more reliably predicts Plavix resistance than thromboelastography. In addition to determining Plavix susceptibility, patients may also obtain benefit by initiating DAPT at least 7 days prior to surgery.