You may already know heart disease causes one of every four deaths in America. You may also know that the most common cause of heart disease is coronary artery disease. And everyone should know that not smoking, eating a healthy diet, getting regular exercise and keeping a healthy weight helps your heart. But here are seven facts you should know—but might not—about heart disease. 1. Deaths from heart disease are actually dropping. Over the past 40 years, the number of deaths from heart disease has fallen by 60%. This is probably because both prevention and treatment methods are better. For instance, fewer people are smoking, and more people have control of conditions like high blood pressure. Some heart doctors even think we could get rid of heart disease in the future. However, today heart disease is still the leading cause of death in the United States. 2. Most people don't know the warning signs of a heart attack. Just 27% of Americans know heart attack warning signs, according to the Centers for Disease Control and Prevention (CDC). That may be why almost half of the people who die suddenly from heart disease do so outside of a hospital. Remember these heart attack warning signs: Chest pain Shortness of breath Nausea Cold sweat Pain in the jaw, neck, arms, back or stomach Call 911 if you or someone else has these major warning signs. It's also important to know that older people, diabetics, and women are more likely to experience symptoms such as shortness of breath, weakness, nausea and vomiting, heart palpitations, and dizziness—without any chest discomfort. 3. Half of all Americans have a key heart disease risk factor. The CDC notes that 49% of people in the United States have high cholesterol or high blood pressure or are smokers. Each of those things makes heart disease more likely. Too much of the bad type of cholesterol, low-density lipoprotein (LDL), can clog your arteries. High blood pressure can harm the walls of your arteries as blood pushes against them over time. And, the chemicals in tobacco smoke affect your blood vessels in a way that makes plaque more likely to build up. In fact, the more you smoke, the higher your risk of heart disease. Other things can also make heart disease more likely including: Having diabetes Being overweight or obese Drinking too much alcohol Not getting enough exercise Eating an unhealthy diet 4. Chewing an aspirin helps during a heart attack. It’s true. One aspirin can help prevent damage from a heart attack. If you have signs of a heart attack, the first thing to do is call 911. Next, chew one 325-milligram aspirin while you wait for the ambulance. Most heart attacks result from a clot that forms when plaque breaks off in an artery that supplies blood to the heart. Aspirin helps make clots go away. Studies show that chewing the pill works faster than swallowing it. 5. A flu shot can help your heart. Everyone with heart disease needs to get a flu shot every year. Heart disease can make you too weak to fight off the flu. And, flu can make heart disease worse. That, in turn, makes your heart attack risk go up. Make sure to get the shot, however, and not the nasal spray. People with heart disease should not get the nasal spray form of the flu vaccine. 6. Depression makes heart disease more likely. People with a chronic disease often develop depression. That includes people with heart disease. That might not be surprising, but did you know that the opposite is true, too? Having depression increases your risk of heart disease. It also can make heart disease worse. And, it increases your chances of dying from a heart attack. This may be because depression, in part, can lead to behaviors that harm the heart. These include things like smoking, drinking and not exercising. 7. Watch out for heart problems on Mondays. Heart attacks seem to occur at certain times more often than others. They're most common on Monday mornings and in the fall and winter. That's according to research published in the journal Circulation Research in 2010. The study found that morning heart attacks also are more serious. The researchers think that the transition period between sleeping and waking may be the most dangerous time for a heart attack. Circadian rhythm, the body's internal clock, may play a role in this.