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Calcium-channel blockers decrease clopidogrel-mediated platelet inhibition

Thomas Gremmel1, Sabine Steiner, Daniela Seidinger

  • 1Division of Angiology, Department of Internal Medicine II, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria. thomas.gremmel@meduniwien.ac.at

Heart (British Cardiac Society)
|August 19, 2009
PubMed

Insights

Calcium-channel blockers (CCBs) reduce the effectiveness of clopidogrel, an antiplatelet medication. This can lead to higher risks for patients undergoing stenting procedures, impacting cardiovascular outcomes.

Area of Science:

  • Cardiology
  • Pharmacology

Background:

  • Clopidogrel's antiplatelet effect varies significantly among individuals.
  • Low response to clopidogrel is linked to increased adverse events post-coronary stenting.
  • Dihydropyridine calcium-channel blockers (CCBs) inhibit CYP3A4, an enzyme crucial for clopidogrel activation.

Purpose of the Study:

  • To evaluate how CCBs affect clopidogrel's ability to inhibit platelet aggregation.

Main Methods:

  • Assessed adenosine-5-diphosphate (ADP)-inducible platelet reactivity using light transmission aggregometry (LTA) and VerifyNow P2Y12 assay.
  • Included 162 patients post-percutaneous intervention with stent implantation.
  • Defined high on-treatment residual platelet reactivity as results in the fourth quartile of both assays.

Main Results:

  • Patients on CCBs exhibited significantly higher on-treatment platelet reactivity compared to those not on CCBs (p=0.001 for both assays).
  • High residual platelet reactivity was more prevalent in patients taking CCBs (p=0.001 for LTA, p=0.004 for VerifyNow P2Y12).
  • Multivariate analysis identified CCB therapy as an independent predictor of diminished clopidogrel efficacy (p=0.006 for LTA, p=0.004 for VerifyNow P2Y12).

Conclusions:

  • CCBs significantly reduce clopidogrel's antiplatelet effect in patients undergoing angioplasty and stenting.
  • This interaction may increase the risk of adverse cardiovascular events in patients treated with both medications.
Abstract

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