Heart disease is still the No. 1 killer of men and women in the United States, but advances over the past 20 years — medications to lower cholesterol and blood pressure, cardiac diagnostic testing, interventional procedures and prevention — have allowed Americans to live longer.

The most common type of heart disease in the United States is coronary artery disease, or CAD, which can lead to a heart attack. CAD occurs when plaque, made of cholesterol deposits, builds up in the arteries that supply blood to the heart, narrowing the arteries in a process called atherosclerosis. Plaque buildup can cause chest pain or angina, which occurs because the heart muscle doesn’t get enough blood. Over time, CAD can weaken the heart muscle and lead to an irregular heartbeat (arrhythmia) or heart failure, a serious condition in which the heart cannot pump blood as it should.

Risk factors for CAD include conditions, behaviors and heredity. High cholesterol, high blood pressure and diabetes place you at risk for atherosclerosis and CAD. Behaviors such as tobacco use, excessive alcohol intake, an inactive lifestyle and diets high in saturated fats and cholesterol increase your risk. High levels of salt or sodium in the diet raise blood pressure levels. Obesity is linked to high blood pressure, diabetes and higher LDL (bad) cholesterol and triglyceride levels and lower HDL (good) cholesterol. Unrelieved stress in your life may damage your arteries and worsen other risk factors for CAD.

Family medical history, gender and age increase your risk of CAD. Genetic factors likely play some role in high blood pressure, heart disease and other vascular conditions. The risk for heart disease increases when heredity is combined with unhealthy lifestyle choices such as smoking cigarettes and a poor diet. Simply getting older increases your risk of damaged and narrowed arteries. Men are generally at greater risk of CAD; however, the risk for women increases after menopause.

For some people, the first sign of CAD is a heart attack caused by a totally blocked coronary artery. Plaque deposits can break off and clot an artery, blocking blood flow through the heart muscle. When the heart muscle is starved of oxygen and nutrients, it is called ischemia, resulting in damage or death of part of the muscle.

Symptoms of a heart attack include sudden chest pain or discomfort in the center of the chest that lasts more than a few minutes or that goes away and comes back. The pain can feel like uncomfortable pressure, squeezing or fullness. Pain or discomfort can occur in one or both arms, the back, neck, jaw or stomach. You may experience shortness of breath with or without chest pain, pressure or tightness in the chest during physical activity or under emotional stress. Other signs include breaking out in a cold sweat, nausea or lightheadedness. Like men, women commonly have chest pain or discomfort as a symptom but are also more likely to experience shortness of breath, nausea and vomiting, back pain or jaw pain.

If you or someone else may be having a heart attack, call 911 immediately. Do not tough out the symptoms of a heart attack for more than five minutes. The saying in the medical field is, “Time is muscle” — the longer the time, the greater chance of heart muscle damage. Do not drive yourself to the hospital unless there is no other option; you place others at risk if you become unconscious at the wheel. While waiting for the ambulance, chew a regular aspirin to reduce clotting and help blood flow through a narrowed artery. Take nitroglycerin if it has been prescribed. Use an automated external defibrillator if one is available.

If the person suspected of having a heart attack is unconscious, the 911 dispatcher may advise you to begin CPR and can instruct you until help arrives. If you do not know CPR and help from the dispatcher is not available, begin by pushing hard and fast on the person’s chest over the heart for one minute, about 100 compressions a minute. When paramedics arrive, they can continue CPR, start cardiac care and transport to the hospital. Tell them and the emergency room staff if you chewed aspirin or took nitroglycerin.

If you have CAD, you can lower your risk for heart attack or worsening heart disease by following a healthier diet, exercising and not smoking. Manage stress with techniques such as muscle relaxation and deep breathing. Medications can treat high cholesterol, high blood pressure, an irregular heartbeat and low blood flow; in some cases, more advanced treatments and surgical procedures can restore blood flow to the heart. People who have had a heart attack can reduce the risk of future attacks or strokes by making lifestyle changes and taking medication.

When traveling, be aware that high altitudes can make those with CAD more symptomatic because the heart has to work harder. Pack your medications and talk to your doctor about travel plans to get advice on precautions you may need to take.

Million Hearts is a national initiative to prevent 1 million heart attacks and strokes over the next five years, bringing together communities, health systems, nonprofit organizations, federal agencies and private partners.

The content of this article is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition.