Effect of Prior Aspirin Treatment on Patients with Acute Coronary Syndromes: Insights from the PROSPECT Study

BACKGROUND: Prior aspirin treatment is considered a risk factor for adverse outcomes in acute coronary syndrome (ACS) patients. The relationships between aspirin pretreatment and findings on quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS), as well as clinical outcomes, are not well understood. METHODS: In the PROSPECT trial, QCA and triple-vessel IVUS imaging were performed after successful percutaneous coronary intervention (PCI) of the culprit lesion(s) in ACS patients. We compared patients receiving aspirin within 7 days of enrollment to those naive to aspirin. Propensity score matching was performed to adjust for differences in baseline characteristics. RESULTS: Aspirin-pretreated patients (n ≤ 236; 35%) were older and more likely to have known coronary disease than those without pretreatment (P≤.01 for all). Pretreated patients had more untreated non-culprit lesions with angiographic and IVUS characteristics predictive of future events (53.1% vs 38.6%; P<.001). There were no significant differences in overall major adverse cardiac event (MACE) rates at 3 years between the aspirin and no-aspirin groups (23.6% vs 18.8%, respectively; P≤.17) in unadjusted or propensity-adjusted analyses. Prior aspirin use was not an independent predictor of MACE at 3 years (hazard ratio, 1.21; 95% confidence interval, 0.73-2.01; P≤.45). CONCLUSION: In the PROSPECT trial, aspirin pretreatment identifies an older population with more advanced coronary disease. Aspirin pretreatment was not an independent predictor of MACE in ACS patients treated with an early invasive strategy. The extent to which aspirin pretreatment is a risk factor for adverse events after PCI in ACS should be revisited.