High on-aspirin platelet reactivity predicts cardiac death in acute coronary syndrome patients undergoing PCI

Objective: To evaluate the possible role of high on-aspirin platelet reactivity (HaPR) in a prospective cohort of
acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI).
Background: Several studies documented that high on-clopidogrel platelet reactivity (HcPR) is associated with
increased risk of ischemic events in ACS patients undergoing PCI. On the contrary, conflicting data are available
on HaPR and clinical outcome.
Methods: Platelet reactivity was assessed by light transmittance aggregometry using arachidonic acid as an
agonist in 1789 ACS patients undergoing PCI.
Results: HaPR was found in 20.3% of patients. These patients were significantly older, with a higher prevalence of
hypertension, diabetes and reduced ejection fraction. Patients with non ST-segment elevation ACS, 3-vessel disease
andmultivessel PCI had a significantly higher prevalence of HaPR. In addition, stent number and length, and
use of drug-eluting stents were significantly higher in HaPR patients. At 24-month follow-up the prevalence of
cardiac death was 9.7% in HaPR and 3.8% in non-HaPR [HR2.63(1.72–4.02), p b 0.0001], that of stent thrombosis
6.1% in HaPR and 2.6% in non-HaPR [HR2.4(1.42–4.07), p b 0.001],with no significant differences in other clinical
end-points. At multivariate analysis, HaPR was confirmed as an independent risk factor for cardiac death
[HR1.88(1.21–2.93), p = 0.005] and stent thrombosis [HR1.91(1.12–3.28), p = 0.018]. The addition of HaPR to
amodel including clinical and procedural risk factors and HcPR led to a significant improvement in the prediction
of cardiac death (NRI 39 ± 10%, p = 0.0003) and stent thrombosis (NRI 34.7 ± 13.2%, p=0.009).
Conclusion: HaPR was found to be an independent risk factor for cardiac death and stent thrombosis in ACS
patients undergoing PCI.