The Impact of Aspirin Resistance on the Long-term Cardiovascular Mortality in Patients with Non-ST Segment Elevation Acute Coronary Syndromes

Background: Aspirin resistance has been associated with an adverse long-term outcome in patients with atherosclerotic coronary artery disease, but more studies are needed. Hypothesis: The aim of this study was to investigate the impact of aspirin resistance, assessed by the Platelet Function Analyzer-loo (PFA-100) (Dade Behring Inc., Deerfield, ILL., USA) on the long-term prognosis in patients with non-ST segment elevation acute coronary syndromes (NSTE-ACS). Methods: A total Of 496 consecutive patients were studied. The 1-y incidence of cardiovascular death was the prespecified study endpoint. The patients were divided, according to the values of PFA-100 collagen epinephrine closure time (CEPI-CT) upon presentation, into aspirin sensitives (those with a PFA-100 CEPI-CT >193 sec) and aspirin resistants (those with a PFA-100 CEPI-CT <= 193 sec). Results: Aspirin resistants were younger (p-value = 0 04), and less frequently hypertensives (p-value = 0.05) or diabetics (p-value = 0.04) than aspirin sensitives. By 1 y, the incidence of cardiovascular deaths in the entire cohort was 12.9% (64/496), and aspirin resistants were at significantly higher risk of cardiovascular death (23.1% versus 9.6%; hazard ratio [HR] = 2.6; 95% confidence interval [CI] = 1.6-4.3; p-value <0.001), than aspirin sensitives. By multivariate Cox regression analysis, aspirin resistance (a PFA-100 CEPI-CT <= 193 sec) was among the most potent predictors of the 1-y incidence of cardiovascular death (HR = 2.8; 95% CI = 1.7-4.6; p-value < 0.001). Conclusion: According to the present data, aspirin resistance, assessed by the PFA-100, is an independent predictor of long-term cardiovascular mortality in patients with NSTE-ACS.