Understanding Heart Attack: The Basics
What Causes a Heart Attack?
Most heart attacks are the result of coronary artery disease, also known as atherosclerosis or "hardening of the arteries," a condition that clogs coronary arteries with fatty, calcified plaques over time. The typical trigger for a heart attack is often a blood clot that blocks the flow of blood through a coronary artery.
In the early 1980s, researchers confirmed that the trigger for nearly all heart attacks is not the obstructive plaque itself, but the sudden formation of a blood clot -- like a scab -- on top of plaque that cuts off blood flow in an already narrowed vessel. This is called "plaque rupture." Contrary to prior belief, doctors now recognize that the less severe plaques are the cause of most heart attacks: It's the milder blockages that rupture and then cause the blood clot to form.
Heart attacks may also be caused by coronary artery spasm, where a heart artery is temporarily constricted, although this is a fairly rare cause.
New research shows that inflammation also plays a role in the evolution of heart attacks. It appears that the coronary artery walls become inflamed over time, further increasing the buildup of fatty plaques.
While the step-by-step process leading to a heart attack is not fully understood, major risk factors for coronary artery disease are well-known. Some can be controlled, including high blood pressure, high cholesterol, obesity, smoking, and a sedentary lifestyle. Stress is also said to raise the risk, and exertion and excitement can act as triggers for a heart attack.
Other risk factors include having diabetes and having a family history of heart disease.