Prasugrel versus clopidogrel for residual thrombus burden in patients with ST-segment elevation myocardial infarction

BACKGROUND: Prasugrel was shown to inhibit platelet activity more rapidly and consistently than clopidogrel. We compared the effects of prasugrel and clopidogrel on residual thrombus burden assessed by optical coherence tomography after stent implantation in patients with ST-segment elevation myocardial infarction (STEMI). PATIENTS AND METHODS: A total of 76 patients with STEMI undergoing percutaneous coronary intervention (PCI) within 12 h after the onset were retrospectively enrolled. Of them, 34 patients were treated with prasugrel (loading dose, 20 mg) and the remaining 42 with clopidogrel (loading dose, 300 mg). Stent volume and in-stent thrombus volume were assessed by post-PCI optical coherence tomography. RESULTS: Baseline clinical characteristics, angiographic findings, and PCI procedure did not differ between the two groups. There was no difference in in-stent volume between patients with prasugrel and clopidogrel [169 (134-214) versus 166 (128-210) mm, P=0.83]. Patients with prasugrel had a significantly reduced in-stent thrombus volume compared with those with clopidogrel [0.59 (0.16-1.09) vs. 1.08 (0.32-2.30) mm, P=0.03]. The mean area and maximum area of in-stent thrombus were also significantly smaller in prasugrel than in clopidogrel group [0.03 (0.01-0.05) vs. 0.05 (0.01-0.10) mm, P=0.04, and 0.45 (0.27-0.75) vs. 0.77 (0.34-1.23) mm, P=0.03, respectively]. CONCLUSION: Prasugrel more effectively reduced residual thrombus burden after stent implantation in patients with STEMI, indicating a faster and more potent platelet inhibitory effect of prasugrel compared with clopidogrel.