A 62-year-old man presents to a small rural emergency department 2 hours after the onset of central, crushing chest pain radiating to his left arm. He is diaphoretic but haemodynamically stable. ECG shows 1-2 mm horizontal ST depression in leads V2-V5 and T-wave inversion in leads II, III and aVF. High-sensitivity troponin I is 230 ng/L (normal <14 ng/L). There is no contraindication to antiplatelet therapy, and transfer to a tertiary centre with a catheter laboratory will take 4 hours. What is the most appropriate immediate antiplatelet regimen to commence now?