Association of Aspirin Dosage to Clinical Outcomes after PCI: Observations from the Ottawa Heart Institute PCI Registry

Volume 21 - Issue 3 - March, 2009
Posted on: 3/10/09
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Association of Aspirin Dosage to Clinical Outcomes after Percutaneous Coronary Intervention: Observations from the Ottawa Heart Institute PCI Registry (full title)

Derek So, MD, ^*E. Francis Cook, MD, Michel Le May, MD, Chris Glover, MD, William Williams, MD, Andrew Ha, MD, Richard Davies, MD, Michael Froeschl, MD, Jean-Francois Marquis, MD, Edward O’Brien, MD, Marino Labinaz, MD

From the University of Ottawa Heart Institute, Ottawa, Ontario and ^*Harvard School of Public Health, Boston, Massachusetts.

Disclosures: Michel Le May has received speaker honoraria from and is a consultant to Sanofi and has received research grants from Schering. Derek So has received speaker honoraria from Sanofi-Aventis and travel grants from Astra-Zeneca.

Manuscript submitted July 15, 2008, provisional acceptance given August 19, 2008, manuscript accepted November 10, 2008.

Address for correspondence: Derek So, MD, FRCPC, University of Ottawa Heart Institute, Cardiology, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada. E-mail: dso@ottawaheart.ca

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ABSTRACT: Background. Dual antiplatelet therapy, with aspirin and a thienopyridine, is the accepted treatment after percutaneous coronary intervention (PCI). No clear evidence exists regarding the ideal dosage of aspirin. Recent guidelines recommend higher-dose aspirin because of the possible decrease in stent thrombosis. The purpose of this study was to test the hypothesis that high-dose aspirin of 325 mg decreases death and myocardial infarction (MI) compared to a lower dose of 81 mg in patients undergoing PCI. Methods. An observational cohort study of 1,840 consecutive patients who underwent PCI was conducted. Patients who did not survive to discharge were excluded. The primary endpoint was a composite of all-cause mortality and MI at 1 year. Results. Nine-hundred and thirty patients (50.5%) were discharged on 325 mg of aspirin and 910 (49.5%) were discharged on 81 mg. The risk of all-cause mortality or MI was not significantly different between patients: low-dose 5.49% (50/910) vs. high-dose 4.19% (39/930); adjusted odds ratio [OR], 1.16; 95% confidence interval [CI], 0.73–1.85). In a multivariable analysis, the Charlson comorbidity score (OR, 1.37; 95% CI, 1.18–1.58) and urgent PCI (OR, 1.75; 95% CI, 1.03–3.00) were associated with increased death or MI. Among patients with drug-eluting stents, the use of low-dose aspirin did not predispose them to death or MI (adjusted OR, 1.12, 95% CI, 0.53–2.34). Conclusions. In this large contemporary analysis of PCI patients, no differences in death or MI were observed at 1 year between patients discharged on low-dose aspirin 81 mg compared to patients on a higher dose.

J INVASIVE CARDIOL 2009;21:121–127

Key words: aspirin dosage, percutaneous coronary intervention

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Percutaneous coronary intervention (PCI) is the most common revascularization procedure, with over 1 million performed each year worldwide.¹ Despite advances in PCI technology, it is well recognized that the utilization of appropriate adjunctive pharmacotherapy is imperative to long-term success after PCI.²