Every day, 3,000 Americans suffer heart attacks. And a few hundred die. What's most frightening, perhaps, is that it usually happens without any warning.
"This disease can strike out of the blue," Dr. Peter Libby of Brigham and Women's Hospital in Boston told ABC News. "In about half of men and almost two-thirds of women, a sudden heart attack, or mini heart attack, can be the first sign that they have any trouble with their heart."
There are plenty of sophisticated ways to test the heart: stress tests, CT scans or angiograms -- real-time X-rays looking for blocked arteries.
These tests are good at detecting the slow, chronic build-up of plaque in the arteries that can cause blockages, but that's not the way most heart attacks occur. Most are triggered by something smaller and more violent -- often, a tiny piece of plaque in an artery that suddenly ruptures.
"Think of a popcorn kernel and what happens when you put it in a microwave," Libby said. "It all of a sudden bursts open. ... Plaque is like the popcorn kernel."
Once a piece of plaque bursts on an artery wall, it can cause a blood clot, completely blocking the flow of blood within seconds. This is how someone with no visible symptoms can experience sudden heart death.
If doctors cannot reliably predict whether you're likely to have a deadly heart attack, prevention becomes all the more critical. Here are a list of some of the most effective measures.
Keep cholesterol levels low: If you have high cholesterol, you can often lower it with the use of medications called statins, which not only prevent the buildup of plaque in arteries, but "stabilize" the plaque so it's less likely to rupture.
Do not smoke: Smoking is extremely damaging to blood vessels.
Avoid excess weight: Fat is especially dangerous around the stomach. Dr. Cam Patterson of the University of North Carolina explains: "Abdominal obesity is so bad because we know now that fat cells in the abdomen secrete chemicals that irritate the arteries around the heart, making it more likely that the plaque is going to rupture."
Get regular exercise: For a healthy heart, you should get cardiovascular exercise at least 30 minutes a day, four times a week.
"There is good evidence that regular exercise grows new blood vessels and strengthens the heart, so if you do suffer a heart attack, you're more likely to survive it," said Dr. Daniel Rader, of the University of Pennsylvania School of Medicine.
Together, these prevention strategies do work. Over the last 20 years, they have helped save 341,000 American lives -- an impressive 50 percent cut in the death rate from heart disease. You can lower your risk of a sudden deadly heart attack. But you cannot always prevent it.