08/21/2012 01:03 pm ET

How Aspirin Helped Save Rosie O'Donnell During Her Heart Attack

Rosie O'Donnell had a heart attack last week after helping a woman from her car, according to news reports.

O'Donnell, 50, did not call 911 as she experienced the symptoms -- nausea, pain, and feeling hot. But she did take a Bayer aspirin -- "saved by a tv commercial, literally" she wrote on her blog -- before seeing a cardiologist the next day.

She wrote on her blog that her left anterior descending artery was 99 percent blocked (what is dubbed a "Widow Maker" heart attack). She had a stent put in to open up the blocked artery.

"Know the symptoms ladies, listen to the voice inside, the one we all so easily ignore, CALL 911," O'Donnell wrote on her blog.

So how did aspirin help to save O'Donnell's life? Well first, it's important to understand how a heart attack forms in the first place. In general, a heart attack occurs when artery-blocking plaques rupture. When this rupture occurs, blood cells called platelets come to the surface. The Harvard Medical School Family Health Guide explains why this is dangerous:

Platelets are the tiny blood cells that trigger blood clotting. A clot, or thrombus, builds up on the ruptured plaque. As the clot grows, it blocks the artery. If the blockage is complete, it deprives a portion of the heart muscle of oxygen. As a result, muscle cells die —- and it's a heart attack.

The sooner aspirin is taken once a heart attack occurs, the better. That's because aspirin works by stopping platelets from building up, in essence thinning the blood, the American Heart Association reported.

And you don't have to take a lot of aspirin -- just a little bit is all it takes to have the inhibitory effect, according to the Harvard Medical School Family Health Guide.

Aspirin isn't just useful during a heart attack -- the American Heart Association recommends taking aspirin to help prevent heart attack in high-risk people, or in people who have already once suffered a heart attack.

However, it's important to talk to your doctor before starting a daily aspirin regimen, as it may not be right for people with certain conditions or in certain low-risk people, the American Heart Association noted. ABC News reported on a recent study in the Journal of the American Medical Association showing that taking 300 milligrams (or less) of aspirin a day could increase bleeding risks in the stomach and brain by 55 percent.

"If the risk of having a cardiovascular event is low, then the risk of bleeding will likely offset any beneficial effect of aspirin," the researcher of that study, Dr. Antonio Nicolucci, told ABC News.