A 63‑year‑old man presents to the emergency department with 45 minutes of central chest tightness radiating to his left arm, associated with diaphoresis and nausea. His blood pressure is 160/92 mmHg, heart rate 104 bpm, oxygen saturation 97% on room air and ECG shows 2 mm ST‑segment elevation in leads V2-V5. What is the most important immediate pharmacological intervention that should be given first?