First off a heart attack known as a myocardial infarction is caused by a lack of blood flow to the heart muscle due to a clot the blocking that blood flow. There are many factors that contribute to the clot being formed and ultimately thrown (translocation) which may include poor diet, smoking, lack of exercise, age and genetic predisposition. The clotting itself is actually very complex involving a cascade of events involving many components one of which is prostaglandin. Aspirin inhibits prostaglandin thereby inhibiting clot formation. This is why an aspirin regimen is first line in myocardial infarction. Other disease factors are usually present such as hypertension (high blood pressure) and hypercholesterolemia (high cholesterol) to name a few. The best prevention is diet exercise and regular checkups with your doctor including treadmill results at given intervals (every 5-10 yrs).