Final answer:
Revascularization therapy is the most important intervention in reducing the patient's mortality rate.
Step-by-step explanation:
The most important intervention in reducing this patient's in-hospital and 30-day mortality rate is to provide revascularization therapy as soon as possible. Revascularization therapy involves restoring blood flow to the blocked coronary artery, typically through procedures such as balloon angioplasty and stents or bypass surgery. This is crucial in treating ST-elevation myocardial infarction (STEMI) as it helps to restore cardiac blood flow and prevent further damage to the heart muscle.