Comparison of Platelet Reactivity in Black Versus White Patients With Acute Coronary Syndromes After Treatment With Ticagrelor

Ticagrelor, a potent platelet inhibitor, has primarily been studied in white patients. Platelet reactivity among black patients with acute coronary syndrome (ACS) on ticagrelor, however, is unknown. Our objective was to compare platelet reactivity in black versus white patients with ACS treated with ticagrelor. We conducted a prospective, pharmacodynamic study of 29 black patients with ACS treated with ticagrelor. Platelet reactivity was assessed at 1, 4, and 8 hours after a loading dose of ticagrelor 180 mg and at 30 days on a maintenance dose of ticagrelor 90 mg twice daily. Assays included light transmission aggregometry, VerifyNow P2Y12, and vasodilator-stimulated phosphoprotein. We provided comparison with a historical white cohort. Platelet reactivity among blacks with ACS on ticagrelor was similar to that in whites, except that blacks had lower values at 4 hours, 8 hours, and on maintenance therapy for light transmission aggregometry with 20 μmol/L adenosine diphosphate. Among blacks, high-on-treatment platelet reactivity for all 3 assays was uncommon at 1 hour and nonexistent at 4 hours, 8 hours, and while on maintenance therapy. Blacks preloaded with clopidogrel (n = 17) had significantly lower results of VerifyNow (64 ± 65 vs 198 ± 86, p <0.001) and vasodilator-stimulated phosphoprotein (12.8 ± 21.6 vs 58.9 ± 19.9, p <0.001) at 1 hour compared with those with no clopidogrel preload. In conclusion, among patients with ACS receiving ticagrelor, levels of platelet reactivity in blacks are similar to that in whites. This suggests that the cardiovascular benefits of ticagrelor observed in the platelet inhibition and patient outcomes (PLATO) trial are likely to be observed in blacks and whites.