Findings from a study assessing the impact of on-clopidogrel platelet reactivity (PR) on hypo-attenuated leaflet thickening (HALT) do not support dual antiplatelet therapy as the standard of care following transcatheter aortic valve replacement (TAVR), researchers say. The study was presented Aug. 27 at ESC Congress 2018 and simultaneously published in JACC: Cardiovascular Interventions.

Researchers prospectively tested whether patients with below-median on-clopidogrel PR have a lower incidence of HALT compared to patients with above-median on-clopidogrel PR. Patients were assigned either chronic dual antiplatelet therapy with clopidogrel and aspirin, or were given bolus doses of both drugs the day before undergoing TAVR. Prior to TAVR, ADP-induced multi-electrode impedance aggregometry was performed before TAVR. Clopidogrel was continued in all patients following TAVR and computed tomography angiography (CTA) was performed to detect HALT.

Results showed 16 patients with below-median ADP-induced PR (< 180 AU*min) were diagnosed with HALT compared with 20 patients with above-median PR. Among patients with high on-clopidogrel PR (>468 AU*min.), seven displayed HALT compared with 19 with ADP-induced PR ≤468 AU*min. Researchers consistently noted that ADP-induced PR as continuous variable was not significantly associated with HALT (p=0.75). However, oral anticoagulation was associated with reduced rates of HALT.

"The level of residual ADP-induced platelet reactivity is not associated with the risk of early HALT as a sensitive marker of emerging valve thrombosis," researchers said. "The current findings question whether P2Y12 inhibition is sufficiently effective in preventing valve thrombosis to justify the increased risk of bleeding associated with it."

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: ESC Congress, ESC18, Angiography

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