Author + information
- Received September 13, 2004
- Revision received January 21, 2005
- Accepted January 25, 2005
- Published online June 7, 2005.
- Peter Wenaweser, MD⁎,
- Janine Dörffler-Melly, MD, PhD†,
- Katja Imboden, BA⁎,
- Stephan Windecker, MD⁎,
- Mario Togni, MD⁎,
- Bernhard Meier, MD⁎,
- Andre Haeberli, MD‡ and
- Otto M. Hess, MD⁎,⁎ ()
- ↵⁎Reprint requests and correspondence:
Prof. Otto M. Hess, Department of Cardiology, University Hospital, Swiss Cardiovascular Center, CH-3010 Bern, Switzerland.
Objectives We sought to evaluate the response to antiplatelet therapy in patients with stent thrombosis (ST).
Background Stent thrombosis is associated with considerable morbidity and mortality. An impaired response to antiplatelet therapy might be related to an increased risk for ST.
Methods Eighty-two patients were included in the present study: 23 patients with previous ST, 50 matched controls (coronary stenting without ST), and 9 healthy volunteers. Platelet aggregation (PA) was studied (optical aggregometry) under monotherapy with acetylsalicylic acid (ASA) 100 mg daily for one month, followed by dual therapy with ASA 100 mg and clopidogrel 75 mg daily (loading dose 300 mg) for another month.
Results Maximal (5 and 20 μmol) adenosine diphosphate-induced PA was significantly higher in patients with ST compared with controls (5 μmol, p < 0.005; 20 μmol, p < 0.05) and volunteers (5 μmol, p < 0.005; 20 μmol, p < 0.05). Resistance to ASA (>20% aggregation with 0.5 mg/ml arachidonic acid) was more prevalent in patients with ST (48%) compared with control patients (32%, p = ns) and volunteers (0%, p = 0.01). Clopidogrel significantly reduced PA in all three groups, but intergroup differences persisted. Clopidogrel resistance (<10% relative change) was similar in patients with ST, control patients, and volunteers (4%, 6%, and 11%, respectively, all p = NS). However, combined ASA and clopidogrel resistance was more prevalent in patients with ST (52%) compared with controls (38%, p = NS) and volunteers (11%, p < 0.05).
Conclusions Patients with previous ST show an impaired response to antiplatelet therapy with ASA compared with controls and volunteers. Additional treatment with clopidogrel is not able to overcome these differences in PA. Acetylsalicylic acid but not clopidogrel resistance appears to be associated with ST.
The Swiss Heart Foundation (to Dr. Dörffler-Melly) and Pfizer SA (to Dr. Hess) provided grant support.
- Received September 13, 2004.
- Revision received January 21, 2005.
- Accepted January 25, 2005.
- American College of Cardiology Foundation