Platelet monitoring can improve outcomes following PCI among clopidogrel resistant patients

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March 29, 2008 By Lauren Ciaglo [mailto: lciaglo@perfuse.org]

SCAI-ACCi2 08-Chicago, IL: Investigators from France demonstrate that platelet monitoring of clopidogrel response using VASP phosphorylation index decreases the rate of major adverse cardiovascular events in patients with clopidogrel resistance.

This study was presented by Dr. Laurent Bonello at the SCAI-i2 summit Annual Scientific Sessions in Chicago today.

Clopidogrel resistance is an important factor to take into account among patients undergoing percutaneous coronary intervention (PCI) particularly those who receive drug eluting stents. Previous studies demonstrated that a poor response to clopidogrel is associated with an increased risk of complications such as in-stent restenosis and stent thrombosis.

The investigators from France studied patients with clopidogrel resistance (defined as more than 50% platelet activity after the standard 600mg loading dose). This study was a multicenter, randomized, prospective study. The outcome measures consisted of myocardial infarction (MI), needed repeat PCI or coronary artery bypass grafting surgery (CABG), or death

This study consisted of 162 patients who were clopidogrel resistant and in need of stenting for treatment of unstable angina. Patients were randomized to one of the two groups: control (n=84) or individually tailored therapy (n=78). The individually tailored therapy consisted of increasing the clopidogrel dose in 600mg increments up to 2,400mg until platelet activity reduced to 50% or less.

The tailored therapy was effective 86% of patients and patients received 1,620 mg of clopidogrel prior to PCI. The platelet activity reduced from 69.3% (after the first loading dose) to 37.6% with tailored therapy assessed by platelet monitoring. In the control group compared with the tailored therapy group the incidence of cardiovascular death was 2% vs. 0%, acute & subacute stent thrombosis was 5% vs. 0% (p=0.059), and revascularization was 2% vs. 0%. There was a significant difference in the composite 30 day outcome between the control group and the tailored therapy group (10% vs. 0% p=0.007 respectively) with no difference in bleeding (5% vs. 4%).

This study demonstrates that tailoring the clopidogrel loading dose according to platelet activity can improve prognosis after PCI. In addition, it is evident from this study that on occasion, a loading dose of clopidogrel several times higher than usual is required in some patients to ensure its effectiveness. Tailored therapy is associated with better cardiovascular outcome following PCI.

Source

1. Late Breaking Clinical Trials Session: SCAI Annual Scientific Sessions in partnership with ACC i2 summit, March 29-April 1, 2008 Chicago
2. SCAI-ACC i2 press release

Reference

http://content.onlinejacc.org/cgi/content/abstract/j.jacc.2007.12.044v1