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Why is aspirin good for your heart?

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With all the fancy prescription pharmaceuticals available for treating heart disease, the idea that one of the best medicines is probably in your home already seems too good to be true. That it's been around since 1899 and costs a few cents a pill seems downright absurd. But it's true: Aspirin can help prevent a heart attack. It can also increase the chance of survival during a heart attack and reduce the risk of a second heart attack.

Heart attacks are caused by a condition called atherosclerosis, otherwise known as clogged arteries. Stated simply, arteries get clogged when plaque builds up on artery walls, caused by too much fat and LDL cholesterol in the bloodstream.

Artery walls are kind of sticky, and certain fats and cholesterols are sticky too, so they build up there, forming a plaque. Plaque is crusty on the outside and mushy on the inside, and it tends to crack. When it cracks, the mushy inside attracts particles in the blood called platelets. Platelets are the blood component that makes your blood clot when you cut yourself. When platelets build up on artery walls, they can cause blood clots. Clots cause severe narrowing of the arteries, which can cause a heart attack. (See What's more likely -- death by an auto accident or death by French fries? to learn more about heart disease.)

Aspirin prevents heart attacks by keeping these blood clots from forming. The mechanism that makes aspirin good for the heart is pretty much the same as the one that makes it good for aches and pains.

In this article, we'll look at exactly what aspirin does to thwart heart attacks and find out how effective it really is. We'll also find out whether you should be talking to your doctor about starting a daily aspirin regimen, or if you should avoid that type of aspirin use.

First, why does it stop clots from forming in the first place?

Aspirin Therapy

Does an aspirin a day keep the doctor away?
Does an aspirin a day keep the doctor away?
James Keyser/Time Life Pictures/Getty Images

Aspirin relieves headaches because of its effect on a chemical called cyclooxygenase. Cyclooxygenase is an enzyme the body uses to produce a chemical called prostaglandin. Prostaglandin is activated when the body is hurt. It tells the brain there is an injury somewhere, and the brain in turn activates the sensory response we know as pain. So, if you have an infection and your body temperature rises, causing a fever, prostaglandin tells your brain there's a problem, and your brain triggers a headache.

When you feel a headache and take an aspirin, the result is that cyclooxygenase production is inhibited, leading to a decrease in prostaglandin production and therefore a decrease in pain response.

People have used aspirin for things like headaches for more than a hundred years. In the 1980s, a group of 22,000 men, all doctors, did a little experiment. Half the subjects took an aspirin every other day, and half took a placebo. At the end of the study, twice as many members of the group taking the placebo had experienced heart attacks compared with the aspirin group [source: YHF].

People who take the recommended dose of between 80 mg and 325 mg a day have a better chance of avoiding heart attacks and, if they do have one, of surviving it [source: MedicineNet]. Why is aspirin so good for people with heart disease?

It's because it blocks cyclooxygenase and, in turn, certain prostaglandins. As it turns out, prostaglandins don't just trigger the feeling of pain. Some of them also help blood platelets clump together to form clots. Aspirin is an antiplatelet agent. It inhibits that prostaglandin that makes platelets stick together. If clots can't form in arteries, the chances of a heart attack decrease dramatically.

Much research has been done since that initial large-scale study in the '80s, and it has consistently backed up the results that brought aspirin into the heart-health arena. Studies have shown that women on a daily aspirin regimen have about 25 percent decreased risk of heart attack [source: YHF]. An American Heart Association study published in 1997 estimated that if everyone having a heart attack chewed an aspirin as soon as they started experiencing chest pain, thousands more people would survive [source: YHF]. That increased survival rate was found to be 23 percent in a study that had heart attack patients chew an aspirin within one hour of the first symptoms [source: MedicineNet]. (See Top 5 Heart Attack Symptoms That Should Have You Calling 911 to learn what to look out for.)

Aspirin isn't always as effective as the more expensive, targeted prescription drugs, but it has the advantage of being cheap, readily available and very beneficial as a preventive measure.

Still, not everyone should take daily aspirin. Some people are allergic to aspirin, and they should always avoid it. Also, since aspirin inhibits blood clotting, people with bleeding disorders and things like ulcers can't use it, because it can lead to uncontrolled internal bleeding. It can interfere with certain medications and it can cause stomachaches and other gastrointestinal problems. In high doses, it can even cause a ringing in your ears.

Because it does have these side effects, doctors usually don't recommend an aspirin regimen for healthy people who do not have disease. For people at low risk, the benefits just don't outweigh the dangers.

For more information on aspirin, heart disease and related topics, look over the links on the next page.

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Sources

  • Aspirin and Antiplatelet Medications. MedicineNet. http://www.medicinenet.com/aspirin_and_antiplatelet_medications/article.htm
  • Aspirin in Heart Attack and Stroke Prevention. American Heart Association. http://www.americanheart.org/presenter.jhtml?identifier=4456
  • Aspirin and Heart Disease. Your Family's Health. http://www.yourfamilyshealth.com/cardiology/aspirin/
  • Heart Disease: Aspirin Therapy. WebMD. http://www.webmd.com/heart-disease/aspirin-therapy