Heart disease is a broad term covering any condition that affects the heart’s structure or function. It includes coronary artery disease, heart failure, valve disorders, rhythm problems, and defects you’re born with. In 2023, cardiovascular disease killed over 919,000 people in the United States, making it the leading cause of death. Understanding what counts as heart disease starts with knowing the distinct ways the heart can malfunction.
A quick clarification on terminology: “cardiovascular disease” is the wider umbrella, covering problems with the heart and all blood vessels in the body. “Heart disease” is more specific, referring only to diseases of the heart itself.
Coronary Artery Disease
Coronary artery disease (CAD) is the most common type of heart disease, affecting about 1 in 20 adults age 20 and older. It develops when a sticky substance called plaque gradually builds up inside the arteries that supply blood to the heart muscle. Over years, this plaque narrows or blocks those arteries, reducing the flow of oxygen-rich blood to the heart.
The process behind this buildup is more complex than simple cholesterol accumulation. It involves chronic inflammation in the artery walls. When the inner lining of an artery is damaged by risk factors like high blood pressure, smoking, or high blood sugar, immune cells migrate into the artery wall and trigger a chain reaction. Fats and cholesterol get trapped there, modified by oxidation, and surrounded by a growing mass of cells and scar-like tissue. Eventually, a lipid-rich core forms inside the artery wall: the classic plaque.
CAD can stay silent for years. Many plaques don’t block enough blood flow to cause symptoms on their own. But when a plaque ruptures or erodes, it can trigger a blood clot that suddenly cuts off flow to part of the heart muscle. That’s a heart attack. Before reaching that point, some people experience angina, a type of chest pain or pressure that typically comes on during exertion and eases with rest. Others develop heart failure over time because the heart muscle, chronically starved of adequate blood supply, weakens.
Heart Failure
Heart failure doesn’t mean the heart stops beating. It means the heart can’t pump blood efficiently enough to meet the body’s needs. It often develops as a consequence of other heart diseases, particularly CAD and long-standing high blood pressure, but it’s considered its own distinct condition.
Doctors measure heart failure partly by looking at ejection fraction: the percentage of blood the heart pumps out with each beat. A normal ejection fraction falls between 55% and 70%. An ejection fraction below 40% typically indicates heart failure with reduced pumping strength. In this type, the heart muscle doesn’t contract forcefully enough to push adequate blood out to the body.
But you can also have heart failure with a normal ejection fraction. This happens when the heart pumps with adequate force but the chambers are too stiff to fill properly between beats. The heart squeezes well, yet less blood enters it in the first place. This form is called heart failure with preserved ejection fraction, and it’s increasingly recognized as a major health problem, particularly in older adults and women. A mildly reduced ejection fraction, between 41% and 49%, may signal early damage or developing cardiomyopathy even before full-blown heart failure sets in.
Arrhythmias
An arrhythmia is any problem with the rate or rhythm of the heartbeat. The heart may beat too fast, too slow, or with an irregular pattern. Some arrhythmias are harmless and barely noticeable. Others are life-threatening.
Atrial fibrillation (AFib) is the most well-known type. In AFib, the heart’s upper chambers quiver chaotically instead of beating in a coordinated rhythm, often producing a rapid and irregular pulse. Some people feel fluttering, dizziness, or fatigue. Others have no symptoms at all and only discover it during a routine checkup. AFib can be intermittent, lasting hours or days before the heart resets itself, or it can become permanent. A related condition, atrial flutter, involves a more organized but still abnormal electrical pattern in the upper chambers. Sick sinus syndrome, which affects the heart’s natural pacemaker, is another electrical disorder that can cause the heart to alternate between beating too slowly and too quickly.
The danger with many arrhythmias isn’t just the irregular heartbeat itself. AFib, for example, significantly raises the risk of stroke because blood can pool and clot in the quivering chambers.
Heart Valve Disease
The heart has four valves that open and close with each beat to keep blood flowing in the right direction. When one or more of these valves doesn’t work properly, it falls under heart valve disease. There are three main types of valve dysfunction.
- Stenosis occurs when a valve opening becomes too narrow, forcing the heart to work harder to push blood through. Over time, this extra workload can weaken the heart.
- Regurgitation (also called backflow or insufficiency) happens when a valve doesn’t seal tightly, allowing blood to leak backward. The heart then has to re-pump that leaked blood, reducing its efficiency. Mitral valve prolapse, where the valve flaps sag and flop backward, is a common cause of regurgitation.
- Atresia is the most severe form. The valve has no opening at all, replaced by a solid sheet of tissue that completely blocks blood flow between heart chambers. This is almost always a congenital problem.
Valve disease can develop from aging, infections, or conditions like rheumatic fever, or it can be present from birth.
Congenital Heart Defects
Heart defects are the most common type of birth defect, affecting nearly 1% of births in the United States, or about 40,000 babies each year. These are structural problems with the heart that form during fetal development. They range from small holes between heart chambers (septal defects) to complex conditions where entire chambers or vessels are malformed.
About 1 in 4 babies born with a heart defect has a critical defect, meaning they need surgery or another procedure within the first year of life. Critical defects include conditions like hypoplastic left heart syndrome, where the left side of the heart is severely underdeveloped, and tetralogy of Fallot, a combination of four structural abnormalities that reduces oxygen levels in the blood.
Surgical repair doesn’t always mean a cure. Many people with congenital heart defects develop additional heart problems over time and need ongoing monitoring with a cardiologist throughout their lives.
Cardiomyopathy
Cardiomyopathy refers to diseases of the heart muscle itself. The muscle may become abnormally thick, stretched out, or stiff, all of which impair its ability to pump. Some forms are inherited, while others result from infections, long-term alcohol use, or other conditions. An ejection fraction above 75% can actually signal one type, hypertrophic cardiomyopathy, where the heart walls thicken excessively and the chambers shrink. Cardiomyopathy is a common pathway to heart failure.
Symptoms Can Look Different in Women
The classic image of a heart attack, sudden crushing chest pain, is more typical in men. Women are much more likely to experience less obvious symptoms: shortness of breath, nausea, back pain, or indigestion, sometimes without any noticeable chest discomfort at all. These differences contribute to delayed diagnosis and treatment in women. Persistent nausea, unexplained abdominal pain, or difficulty breathing that doesn’t resolve deserve medical attention, especially in combination.
How Heart Disease Is Detected
No single test diagnoses all forms of heart disease. The test your doctor chooses depends on which type is suspected.
An electrocardiogram (ECG or EKG) records the heart’s electrical activity and can reveal irregular rhythms, signs of a previous heart attack, or areas of the heart under strain. It’s quick, painless, and often the first test ordered. A stress test takes this further by monitoring your heart while it works hard, typically while you walk on a treadmill or ride a stationary bike. If you can’t exercise, medication can temporarily increase your heart rate to simulate exertion.
For imaging, a coronary calcium scan measures calcium deposits in the artery walls, which correlate with plaque buildup and can help assess risk even before symptoms appear. Coronary CT angiography uses specialized X-rays to visualize blood flow through the coronary arteries. Cardiac MRI can detect tissue damage and blood flow problems, including disease in the small vessels that other tests might miss. When more precise information is needed, invasive coronary angiography threads a thin catheter into the coronary arteries and injects contrast dye to map blockages directly.
Reducing Your Risk
Many forms of heart disease share the same modifiable risk factors: high blood pressure, high cholesterol, smoking, physical inactivity, obesity, and poorly managed diabetes. Addressing even one of these meaningfully lowers your overall risk.
The American Heart Association recommends at least 150 minutes per week of moderate-intensity aerobic activity (brisk walking, cycling, swimming) or 75 minutes of vigorous activity, plus muscle-strengthening exercise on at least two days per week. Greater benefits come at 300 minutes per week or more. For cholesterol, optimal LDL targets vary based on overall risk. People at very high risk of heart attack or stroke may aim for LDL levels below 55 mg/dL, while others may target below 100 mg/dL.
Congenital defects and some arrhythmias can’t be prevented through lifestyle changes. But for the types of heart disease that develop over a lifetime, particularly CAD and heart failure, the same core habits of regular movement, a balanced diet, not smoking, and managing blood pressure and cholesterol make a substantial difference in whether and when disease develops.