Heart disease is the leading cause of death in both men and women. Over 700,000 Americans experience a heart attack every year. You may already be taking steps to reduce your risk, but how do you know if you’re doing enough?

As a result of several long-term studies, scientists have determined key risk factors that can increase your chance of experiencing heart disease or a heart attack over your lifetime. By tracking your risk factors, you can determine how aggressive you need to be in adopting lifestyle changes and treatments.

Your risk for heart disease increases as you age, regardless of your other risk factors. The risk increases for men after the age of 45 and for women after the age of 55, or after menopause. The hormone estrogen is thought to help protect the heart. This is why a drop in estrogen levels in a woman’s body after menopause increases her risk of heart disease.

Over time, the gradual buildup of fatty plaques in the arteries can become a problem. As you get older, this buildup can cause arteries to narrow where the blood is supposed to flow through. Sometimes, a blood clot can form and block your blood flow in a coronary artery. This can cause a heart attack.

Men are at higher risk of heart disease than women. It’s estimated that 70 to 89 percent of sudden cardiac events occur in men. So far, scientists aren’t sure why this is, but studies have indicated that sex hormones may be a cause.

One study regarding male sex and certain hormones found that two sex hormones are linked to increased levels of low-density lipoprotein (LDL), which is considered bad cholesterol, and low levels of high-density lipoprotein (HDL), which is considered good cholesterol. Another study indicated that the Y chromosome, which is unique to men, might also contribute to an increased risk for coronary artery disease. Regardless of the reason, men are at a higher risk for heart disease overall, and they tend to develop it at an earlier age than women. However, heart disease is also the leading cause of death in women.

Your total cholesterol is a potential risk factor for heart disease. The American Heart Association defines total cholesterol as the sum of your HDL and LDL cholesterol levels and 20 percent of your triglyceride level. Cholesterol is a key part of the plaque that can build up in your arteries. Plaque consists of fat, cholesterol, calcium, and other substances. The theory is that the more cholesterol and fat you have in your blood, the higher the chances are that they may be converted into plaque buildup in your arteries.

Scientists have discovered that all cholesterol isn’t the same. HDL cholesterol is actually protective against heart disease. Scientists aren’t exactly sure why, but they believe that it helps to reduce inflammation, which contributes to heart health. It also helps shuttle cholesterol to the liver, where it can be processed out of the body. The general consensus is that the higher your HDL level, the lower your risk of heart disease.

Smoking tobacco products increases your overall risk of heart disease. Nicotine and other chemicals in cigarettes harm the heart and blood vessels, increasing your risk of artery narrowing due to atherosclerosis.

This risk increases even if you only smoke once in a while. Fortunately, no matter how much or how long you’ve smoked, quitting will benefit your heart. It reduces your risk of developing or dying from heart disease, and lowers your risk of atherosclerosis over time. Quitting may also help reverse heart and blood vessel damage.

The first number of your blood pressure reading can also give you a clue about your risk of heart disease. This number refers to your “systolic” blood pressure. This is the pressure in your arteries when your heart beats, and causes blood to pulse against the wall of your arteries. The second number refers to your “diastolic” blood pressure. This is the pressure in your arteries between heartbeats, which is when the heart’s bottom chambers relax.

The systolic measurement typically increases with age. It’s considered more indicative of heart disease risk. This is due to increasing stiffness in the arteries and the long-term buildup of plaque.

Here are some blood pressure guidelines:

  • Normal blood pressure: systolic less than 120 mmHg and diastolic less than 80 mmHg
  • Elevated: systolic 120 to 129 mmHg and diastolic less than 80 mmHg
  • Stage 1 hypertension (high blood pressure): systolic 130 to 139 mmHg or diastolic 80 to 89 mmHg
  • Stage 2 hypertension: systolic 140 mmHg or higher or diastolic 90 mmHg or higher

Taking medications to reduce your blood pressure lowers your risk of having a heart attack.

Many heart disease risk calculators have added diabetes to the list. If you have diabetes, you’re almost twice as likely as someone who doesn’t have diabetes to die from heart disease.

Over time, high blood glucose (sugar) levels can lead to an increase in the deposit of fatty materials against an artery or other blood vessel luminal wall with subsequent artery narrowing and hardening, which is part of a process known as atherosclerosis.

Visit the American Heart Association website to use its heart risk calculator. After answering a few questions about your blood pressure, total and HDL cholesterol, age, and a few other things, the site will give you your percentage of risk. Be sure to get regular checkups with your doctor to manage all of your risk factors and to keep your risk of heart disease as low as possible.