Heart disease is the leading cause of death in the United States, responsible for roughly 1 in every 3 deaths. In 2023 alone, over 919,000 Americans died from cardiovascular disease. The term “heart disease” is actually an umbrella covering several distinct conditions, each affecting a different part of the heart. Here are the most common types, what they do to your body, and how they’re detected.
Coronary Artery Disease
Coronary artery disease is the most well-known form of heart disease and the one most people picture when they hear the term. It starts when fats, cholesterol, and other substances build up along the walls of the arteries that supply blood to your heart. This buildup, called plaque, gradually narrows those arteries. Over time, your heart receives less and less oxygen-rich blood.
The process, called atherosclerosis, is driven largely by cholesterol. Too much LDL (“bad”) cholesterol in the blood encourages plaque to form, while too little HDL (“good”) cholesterol means your body can’t clear that buildup efficiently. If a plaque deposit ruptures, a blood clot can form on the spot and partially or fully block the artery. A completely blocked coronary artery causes a heart attack.
Many people live with narrowed arteries for years without knowing it. Symptoms typically appear during physical activity, when the heart needs more oxygen than the narrowed arteries can deliver. Chest pain or pressure (angina), shortness of breath, and fatigue during exertion are the classic warning signs.
Heart Failure
Heart failure doesn’t mean the heart has stopped. It means the heart can no longer pump blood effectively enough to meet your body’s needs. This can happen in two fundamentally different ways, and doctors distinguish between them using a measurement called ejection fraction, which is the percentage of blood the heart pumps out with each beat.
In heart failure with reduced ejection fraction, the heart muscle has weakened and can’t contract forcefully enough. The ejection fraction drops below 40%, compared to a healthy range of 50% to 70%. In heart failure with preserved ejection fraction, the heart still squeezes normally, but the muscle has stiffened and can’t relax properly between beats. The ejection fraction looks normal on a test, yet the heart still isn’t filling with enough blood. Both types produce similar symptoms: shortness of breath, swelling in the legs and ankles, persistent fatigue, and difficulty exercising.
Heart failure often develops as a consequence of other conditions. Years of uncontrolled high blood pressure, damage from a heart attack, or cardiomyopathy can all push the heart toward failure.
Arrhythmias
Your heart relies on a carefully timed electrical system to coordinate each beat. When that system misfires, the result is an arrhythmia, an abnormal heart rhythm. The heart may beat too fast (tachycardia), too slow (bradycardia), or in a chaotic, irregular pattern.
Atrial fibrillation, often called AFib, is the most common sustained arrhythmia. In AFib, the upper chambers of the heart fire electrical signals rapidly and erratically instead of in a steady rhythm. This causes the heart to quiver rather than contract smoothly, which means blood isn’t pumped as efficiently. AFib also allows blood to pool in the upper chambers, raising the risk of clots that can travel to the brain and cause a stroke.
Some arrhythmias feel like a fluttering or racing sensation in the chest. Others cause dizziness, lightheadedness, or fainting. Mild arrhythmias are common and harmless, but sustained or severe ones can be life-threatening. A standard electrocardiogram (EKG) records the heart’s electrical activity and can catch many rhythm problems. For arrhythmias that come and go, doctors use a Holter monitor, a portable EKG device worn for a day or more during normal activities.
Valvular Heart Disease
The heart has four valves (aortic, mitral, pulmonary, and tricuspid) that open and close with each heartbeat to keep blood flowing in one direction. Valvular heart disease develops when one or more of these valves doesn’t work properly. There are two main ways a valve can fail.
In stenosis, the valve opening becomes too narrow. The flaps may have thickened or stiffened over time, or a person may have been born with an abnormally shaped valve. A common example is a bicuspid aortic valve, where the aortic valve forms with two flaps instead of three. A narrowed valve forces the heart to work harder to push blood through the smaller opening.
In regurgitation (also called backflow or insufficiency), a valve doesn’t seal tightly and allows blood to leak backward. The mitral valve is the most commonly affected, often due to prolapse, where the valve flaps sag and flop back into the upper chamber. Because some blood flows the wrong way with each beat, the heart has to pump harder to deliver enough blood to the body.
An echocardiogram, which uses sound waves to create a moving image of the heart, is the primary tool for spotting valve problems. It shows both the structure of the valves and the direction of blood flow in real time.
Cardiomyopathy
Cardiomyopathy refers to diseases of the heart muscle itself. Rather than a problem with arteries, valves, or electrical signals, the muscle changes shape or texture in ways that make pumping less effective. There are three main types.
Dilated cardiomyopathy is the most common form. The ventricles (the heart’s lower pumping chambers) weaken and stretch larger, reducing their ability to push blood out. Long-term alcohol use, viral infections, and certain medications can cause it, though sometimes no clear cause is found.
Hypertrophic cardiomyopathy involves the heart muscle growing abnormally thick. The thickened walls can block blood flow out of the ventricles. This type is commonly inherited, passed through families by genetic mutations. It’s one of the leading causes of sudden cardiac arrest in young athletes.
Restrictive cardiomyopathy is rare. The ventricle walls stiffen without thickening, so the chambers can’t relax and fill with enough blood between beats. Conditions that cause abnormal protein or scar tissue to build up in the heart muscle are typical triggers.
Congenital Heart Defects
Not all heart disease develops over a lifetime. Congenital heart defects are structural problems present at birth, affecting nearly 1% of newborns, or about 40,000 babies per year in the United States. These defects form during fetal development when the heart’s chambers, walls, valves, or blood vessels don’t develop correctly.
The most common type is a ventricular septal defect, a hole in the wall between the heart’s two lower chambers. Small holes may close on their own as a child grows. Larger ones allow oxygen-rich and oxygen-poor blood to mix, forcing the heart to work harder and potentially leading to heart failure if left untreated. Other congenital defects range from minor valve abnormalities to complex conditions involving multiple structural problems.
Many congenital heart defects are now detected before birth or shortly after through ultrasound and echocardiography. Advances in surgical repair mean that most children born with these defects survive into adulthood, though some require ongoing monitoring throughout their lives.
How Heart Disease Is Detected
Because these conditions affect different parts of the heart, no single test catches them all. Doctors choose based on what they suspect. Blood tests can reveal proteins that leak from damaged heart muscle after a heart attack, along with cholesterol levels and markers of inflammation. A chest X-ray can show whether the heart is enlarged. An EKG records the heart’s electrical rhythm and takes only a few minutes.
For a closer look at the heart’s structure and movement, an echocardiogram provides real-time images using sound waves. Stress tests, where you walk on a treadmill or ride a stationary bike while being monitored, reveal how the heart performs under physical demand. If you can’t exercise, medication can mimic the effect. Cardiac catheterization, where a thin tube is threaded into the heart’s arteries, can pinpoint blockages. Cardiac MRI provides the most detailed images of heart tissue and is particularly useful for diagnosing cardiomyopathies.
Major Risk Factors
Several of these conditions share the same underlying risk factors. High blood pressure, defined as readings at or above 130/80 mm Hg, affects 46% of American adults and is a major driver of coronary artery disease, heart failure, and arrhythmias. High LDL cholesterol accelerates plaque buildup in the arteries. Type 2 diabetes, identified by a hemoglobin A1c level of 6.5% or higher, damages blood vessels over time and roughly doubles heart disease risk.
Smoking, physical inactivity, obesity, and a family history of heart disease all compound the danger. What makes heart disease particularly insidious is that many of these risk factors produce no symptoms for years or even decades. Plaque can quietly narrow your arteries, blood pressure can stay elevated without you feeling it, and blood sugar can creep upward long before a diagnosis. That’s why routine screening for blood pressure, cholesterol, and blood sugar matters, even when you feel fine.