Oral Antiplatelet Therapy in Acute Coronary Syndromes: Recent Developments

Uwe Zeymer

The purpose of this article is to summarize the current knowledge about treatment with oral platelet inhibitors in patients with acute coronary syndrome (ACS). Antiplatelet therapy has been shown to improve the prognosis of patients with ACS with ST segment elevation myocardial infarction (STEMI) and non-ST segment elevation ACS (NSTE-ACS). Aspirin should be given with a loading dose of 250-500 mg, followed by 75-100 mg/day. Dual antiplatelet therapy is recommended for all patients with ACS for 12 months regardless of the initial revascularization strategy. Clopidogrel should be administered at first medical contact in STEMI with a loading dose of 600 mg. In patients with ACS and percutaneous coronary intervention (PCI) 2 × 75 mg clopidogrel should be given daily over 7 days, while in all other patients 75 mg per day appears to be sufficient. The two newer adenosine diphosphate-receptor antagonists prasugrel and ticagrelor lead to a more rapid and effective inhibition of platelet aggregation compared with clopidogrel, which was associated with an improved clinical outcome in two large randomized studies. Prasugrel is indicated in patients with ACS undergoing PCI and was most effective in diabetics and in patients with STEMI. In the recent TaRgeted platelet Inhibition to cLarify the Optimal strateGy to medicallY manage Acute Coronary Syndromes trial in medically treated patients with NSTE-ACS, prasugrel did not significantly reduce ischemic events compared with clopidogrel. Ticagrelor has been studied in the whole spectrum of ACS patients and reduced cardiovascular and total mortality in comparison with clopidogrel. The greatest benefit has been observed in patients with planned conservative treatment and in patients with impaired renal function. Expanding antiplatelet therapy from dual to triple therapy including a platelet thrombin receptor antagonist in the thrombin receptor antagonist for clinical event reduction in acute coronary syndrome trial was not associated with a significant reduction in the primary combined endpoint but an increase in bleeding complications. However, in the Thrombin Receptor Antagonist in Secondary Prevention of atherothrombotic ischemic events study in patients with prior myocardial infarction, vorapaxar on top of standard antiplatelet therapy was effective.