Final answer:
After an EKG confirms STEMI, cardiac catheterization with coronary angiography is usually the next step for visualizing blockages and guiding further interventions, while aspirin administration is an immediate therapeutic measure.
Step-by-step explanation:
The next step in the workup for STEMI after an EKG is typically cardiac catheterization, which aims to visualize the coronary arteries using coronary angiography. If the catheterization identifies a blockage, immediate procedures such as balloon angioplasty, stent placement, or even bypass surgery might follow to restore blood flow. Concurrently, aspirin administration is a crucial initial intervention to help reduce clot formation and improve outcomes prior to more definitive therapies like catheterization. In cases where cardiac catheterization is not immediately available, thrombolytic therapy may be used to dissolve the clot causing the myocardial infarction and is most effective when administered as soon as possible after symptom onset.