Comparison of differential expression of P2Y₁₂ receptor in culprit coronary plaques in patients with acute myocardial infarction versus stable angina pectoris.

P2Y₁₂ receptor antagonists may have pleiotropic benefits. Little is known, however, about the expression of P2Y₁₂ receptors in coronary atherosclerotic plaques. We investigated the expression of P2Y₁₂ receptor in coronary atherectomy tissues retrieved from patients with acute myocardial infarction (AMI) or stable angina pectoris (SAP). Tissue specimens were collected from 35 patients with AMI and 19 with SAP who underwent directional coronary atherectomy. Specimens were analyzed immunohistochemically using antibodies specific to P2Y₁₂ receptor and to markers of endothelial cells, macrophages, and smooth muscle cells. The 2 groups had similar baseline clinical characteristics. Plaque types were more likely to be cellular in the AMI group. The proportion of areas immunopositive for α-smooth muscle actin was smaller but those positive for CD31 and CD68 were larger in the AMI than in the SAP group. In addition, the relative area immunopositive for P2Y₁₂ receptor was significantly larger for AMI than SAP (1.1 ± 0.9% vs 0.5 ± 0.4%, respectively, p < 0.001). P2Y₁₂ receptor positivity coincided with areas positive for CD31 and α-smooth muscle actin. In conclusion, P2Y₁₂ receptor is present in coronary atherosclerotic plaques and is increased in culprit plaques of patients with AMI. P2Y₁₂ receptor may play a role in plaque destabilization.