Association of measured platelet reactivity with changes in P2Y 12 receptor inhibitor therapy and outcomes after myocardial infarction: Insights into routine clinical practice from the TReatment with ADP receptor iNhibitorS: Longitudinal Assessment of Treatment Patterns and Events after Acute Coronary Syndrome (TRANSLATE-ACS) study.

BACKGROUND: Little is known about the use of platelet function testing to guide choice of P2Y12 receptor inhibitor therapy in routine clinical practice.

METHODS: We studied 671 myocardial infarction (MI) patients treated with percutaneous coronary intervention in the TRANSLATE-ACS Registry who had VerifyNow platelet function testing performed while on clopidogrel treatment during their index hospitalization (April 2010-October 2012).

RESULTS: High platelet reactivity (>208 platelet reactivity units [PRU]) was present in 261 (38.9%) patients. Clopidogrel was switched in-hospital to prasugrel in 80 (30.7%) patients with high platelet reactivity and 18 (4.4%) patients with therapeutic platelet reactivity (≤208 PRU). Among high platelet reactivity patients, switch to prasugrel was associated with lower major adverse cardiovascular events (death, MI, stroke, or unplanned revascularization) at 1year (10.0% vs 22.7%, P=.02; adjusted odds ratio [OR] 0.39, 95% CI 0.18-0.85, P=.02) and no significant difference in Bleeding Academic Research Consortium type 2 or higher bleeding (23.8% vs 22.1%, P=.77; adjusted OR 0.91, 95% CI 0.48-1.7, P=.77) compared with patients continued on clopidogrel. No significant differences in major adverse cardiovascular event (22.2% vs 12.8%, P=.25; adjusted OR 1.8, 95% CI 0.47-7.3, P=.38) or bleeding (22.2% vs 19.4%, P=.77; adjusted OR 1.3, 95% CI 0.27-6.8, P=.72) were observed among therapeutic platelet reactivity patients between switching and continuation on clopidogrel.

CONCLUSIONS: Only one-third of percutaneous coronary intervention-treated MI patients with high on-clopidogrel platelet reactivity were switched to a more potent P2Y12 receptor inhibitor. Intensification of antiplatelet therapy was associated with lower risk of ischemic events at 1year among HPR patients.