Background: Data regarding immediate response to P2Y12 inhibitors in STEMI is scarce and was previously associated with adequacy of reperfusion. Our goal was to assess the predictors and significance of the immediate platelet response to prasugrel loading in STEMI.
Methods: Platelet aggregation (PA) was prospectively evaluated in STEMI patients upon prasugrel loading and at primary percutaneous coronary intervention (PPCI). Early platelet responsiveness was defined as percent reduction of PA from baseline to PPCI divided by the time elapsed from loading to PPCI. High and low platelet responsiveness was defined as above and below the median value respectively.
Results: Study population was comprised of 55 consecutive STEMI patients (age 58±9, 91% male) who underwent PPCI with a door to balloon time of 49±17 minutes. Median PA upon prasugrel loading and at PPCI was 78% (interquartile range [IQR] 70-85%) and 72% ([IQR] 59-76%) respectively. On a multivariate analysis predictors of high responsiveness to prasugrel were younger age (OR=1.15 per each year, p=0.04) and higher baseline ADP PA (OR=1.11 per percent increase, p=0.03), while prior aspirin use and smoking were associated
with reduced responsiveness (OR=0.05, p=0.02 and OR=0.05, p=0.01, respectively). Reperfusion markers were significantly improved in the higher response group in comparison to the low response group as reflected by early ST resolution (79% vs. 43%, p=0.02) and peak TnI levels (41 vs. 94 μg/L, p=0.02).
Conclusions: Predictors of immediate platelet responsiveness to prasugrel are younger age, smoking, prior aspirin use, and high baseline ADP reactivity. The immediate responsiveness is associated with improved markers of reperfusion.
