Final answer:
Aspirin may protect against having a first heart attack and is an antiplatelet drug that helps prevent clotting and is usually prescribed preventively when plaque buildup is evident.
Step-by-step explanation:
The drug that may protect against having a first heart attack is aspirin. Aspirin is an antiplatelet drug that helps prevent clotting in patients who have had a heart attack, unstable angina, ischemic strokes, TIA (transient ischemic attacks), and other forms of cardiovascular disease. It is usually prescribed preventively when plaque buildup is evident but there is not yet a major obstruction in the artery. In certain cases, aspirin may also be prescribed in combination with another antiplatelet drug as dual antiplatelet therapy (DAPT).