CORRESPONDENCE: LETTER TO THE EDITOR
Adjusting Clopidogrel Loading Doses According to Vasodilator-Stimulated Phosphoprotein Index: On Time, Too Early, or Too Late?
Thomas Cuisset, MD*,
Corinne Frere, MD, PhD,
Jacques Quilici, MD,
Marie Christine Alessi, MD, PhD and
Jean Louis Bonnet, MD
* CHU Timone, Cardiology, 264 rue Saint Pierre, 13385, Marseille, France (Email: thomascuisset{at}voila.fr).
We have read with great interest the report from Bonello et al. (1). The authors have to be congratulated on publishing the first article to show the clinical benefit of tailored antiplatelet therapy. We would like to address a few comments to the authors.
The clinical evidence supporting the clinical predictive value of the vasodilator-stimulated phosphoprotein (VASP) index is quite low (2,3), and additional large-sample size studies may be required to validate a definite cutoff. The authors used a cutoff of 50%, previously associated with post-percutaneous coronary intervention (PCI) ischemic events, in a small sample size, single-center study (2) with good negative predictive value but poor specificity.
Is it too early? Indeed, before adapting clopidogrel loading dose, maybe we should define a consensual definition of nonresponse?
The difference observed between both groups is highly significant, with no clinical events in the VASP-guided group. This result could suggest that all post-PCI ischemic events are related to nonresponse to clopidogrel, which is probably excessive. These recurrences involve a complex and multifactorial process. The recent TRITON–TIMI 38 (Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition with Prasugrel–Thrombolysis In Myocardial Infarction) study showed that, even with a more potent P2Y12 inhibitor, the rate of recurrent events significantly decreased but continued to exist (4).
The authors reported no excess of major bleeding in the VASP-guided group and concluded that the strategy is safe. However, the sample size of the present study does not allow for such a definite conclusion. What would be the bleeding complications in a broad population of such strategy? Moreover, in the whole population, 52% of the patients had VASP >50%, suggesting the use of this strategy in more than one-half of the PCI patients. Then, will the increased length in hospital stay be acceptable for the public health system?
Is it too late? Indeed, in the near future, the alternative in nonresponders might be to switch to alternative drugs such as prasugrel. Then, the variability of response to clopidogrel would become a resolved issue.
 |
References
|
|---|
1. Bonello L, Camoin-Jau L, Arques S, et al. Adjusted clopidogrel loading doses according to vasodilator-stimulated phosphoprotein phosphorylation index decrease rate of major adverse cardiovascular events in patients with clopidogrel resistance: a multicenter randomized prospective study J Am Coll Cardiol 2008;51:1404-1411.[Abstract/Free Full Text]2. Bonello L, Paganelli F, Arpin-Bornet M, et al. Vasodilator-stimulated phosphoprotein phosphorylation analysis prior to percutaneous coronary intervention for exclusion of postprocedural major adverse cardiovascular events J Thromb Haemost 2007;5:1630-1636.[CrossRef][Web of Science][Medline] 3. Frere C, Cuisset T, Quilici J, et al. ADP-induced platelet aggregation and platelet reactivity index VASP are good predictive markers for clinical outcomes in non-ST elevation acute coronary syndrome Thromb Haemost 2007;98:838-843.[Web of Science][Medline] 4. Wiviott SD, Braunwald E, McCabe CH, et al. Prasugrel versus clopidogrel in patients with acute coronary syndromes N Engl J Med 2007;357:2001-2015.[CrossRef][Medline]
Related Article
-
Reply
- Laurent Bonello, Laurence Camoin-Jau, Stéphane Arques, Paul Barragan, Francoise Dignat-George, and Franck Paganelli
J. Am. Coll. Cardiol. 2008 52: 791-792.
[Full Text]
[PDF]
This article has been cited by other articles:
|
|
|
|
 
S. E. Ghannudi, P. Ohlmann, N. Meyer, M.-L. Wiesel, B. Radulescu, M. Chauvin, P. Bareiss, C. Gachet, and O. Morel
Impact of P2Y 12 Inhibition by Clopidogrel on Cardiovascular Mortality in Unselected Patients Treated by Percutaneous Coronary Angioplasty: A Prospective Registry
J. Am. Coll. Cardiol. Intv.,
June 1, 2010;
3(6):
648 - 656.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
Top
References