A 64-year-old man presents with 90 minutes of central chest pressure radiating to his left arm, associated with diaphoresis and nausea. Blood pressure is 138/84 mm Hg and heart rate 88 beats/min. ECG shows ST-segment depression in V4-V6 and T-wave inversion in II, III and aVF. High-sensitivity troponin is elevated. He has not taken any medications today. Which immediate intervention is most likely to reduce short-term mortality?