CAD stands for coronary artery disease, the most common type of heart disease. It develops when the arteries that supply blood to your heart become narrowed or blocked by a buildup of fats, cholesterol, and other substances along the artery walls. This buildup, called plaque, restricts blood flow to the heart muscle and can eventually cause chest pain, heart attacks, or heart failure.
CAD doesn’t happen overnight. It develops over years or even decades, often without noticeable symptoms until the blockage becomes severe enough to starve the heart of oxygen-rich blood.
How Plaque Builds Up in the Arteries
The underlying process behind CAD is called atherosclerosis. It begins when cholesterol and fats in your blood start collecting along the inner walls of your coronary arteries. Over time, these deposits harden into plaque, which narrows the artery and reduces the amount of blood that can pass through.
If too much LDL cholesterol (the “bad” type) circulates in your blood, plaque formation accelerates. The real danger comes when a plaque ruptures. A ruptured plaque triggers a blood clot at the site, which can partially or completely block the artery. A complete blockage cuts off blood supply to part of the heart muscle, causing a heart attack.
What CAD Feels Like
The hallmark symptom of CAD is angina, a type of chest pain or pressure that occurs when the heart isn’t getting enough blood. Angina comes in two forms, and the distinction matters.
Stable angina follows a predictable pattern. It typically shows up during physical exertion or emotional stress, lasts a few minutes, and goes away with rest. If you have stable angina, you’ll generally learn to recognize when episodes are likely to happen. This form has been consistent for at least two months.
Unstable angina is different and more dangerous. It can be stronger or last longer, doesn’t follow a pattern, and may strike even when you’re resting. Rest or medication may not relieve it. Unstable angina is a medical emergency because it can progress to a heart attack.
Some people with CAD experience no chest pain at all. Instead, they may notice shortness of breath, fatigue during activities that used to feel easy, or pain radiating to the jaw, neck, or arm. Some people, particularly women and people with diabetes, have no symptoms until a heart attack occurs.
Major Risk Factors
Several conditions significantly raise your risk of developing CAD. High blood pressure forces your heart to work harder and damages artery walls over time. High LDL cholesterol feeds plaque growth directly. Diabetes causes sugar to build up in the blood and raises the risk of death from heart disease compared to adults without diabetes. Obesity is linked to higher LDL cholesterol and triglycerides, lower HDL (“good”) cholesterol, and increased likelihood of developing high blood pressure and diabetes.
Lifestyle plays an equally large role. A diet high in saturated fats, trans fats, and sodium accelerates atherosclerosis and raises blood pressure. Physical inactivity increases the chances of developing nearly every other risk factor on this list. Smoking damages blood vessels, raises blood pressure through nicotine, and reduces the oxygen-carrying capacity of your blood through carbon monoxide exposure. Drinking too much alcohol raises blood pressure and triglyceride levels.
Genetics factor in as well. A family history of heart disease increases your risk, though it’s difficult to separate inherited traits from shared diets, habits, and environments within families.
How CAD Is Diagnosed
Doctors use several tests to evaluate whether your coronary arteries are narrowed or blocked. The approach depends on your risk level and symptoms.
For people with stable chest pain and no prior heart disease diagnosis, expert guidelines from the American Heart Association and American College of Cardiology now recommend cardiac CT angiography as a first-line test. This scan involves injecting dye into a vein in your arm and using a CT scanner to create a detailed three-dimensional view of the heart’s arteries. It’s noninvasive and doesn’t require a catheter.
For higher-risk patients, invasive coronary angiography may be more appropriate. This procedure involves threading a thin tube through an artery in your leg or arm up to the heart, then injecting dye visible on X-ray. The advantage is that if a severe blockage is found, the cardiologist can place a stent (a small wire mesh tube to hold the artery open) during the same procedure.
For over 40 years, a 50% narrowing of a coronary artery has been the threshold considered “significant” or “clinically important.” This is the benchmark used in major clinical trials comparing treatments, and it generally marks the point where intervention is considered.
Treatment Options
CAD treatment typically starts with medications to manage symptoms and slow disease progression. Blood thinners like aspirin help prevent clots from forming at plaque sites. Cholesterol-lowering medications reduce plaque buildup. Beta blockers slow the heart rate and lower blood pressure, reducing the heart’s workload and, after a heart attack, lowering the risk of another one. Other blood pressure medications help keep the disease from worsening. Nitroglycerin can relieve acute chest pain by widening blood vessels.
When medications and lifestyle changes aren’t enough, two procedural options exist. Percutaneous coronary intervention (commonly called stenting or angioplasty) opens a blocked artery using a balloon and places a stent to keep it open. Coronary artery bypass grafting (CABG) reroutes blood around blocked arteries using a vessel taken from another part of the body. Both procedures effectively relieve symptoms.
The choice between them depends on the severity of the disease. Bypass surgery is generally preferred for patients with blockages in the left main artery, severe three-vessel disease, diffuse disease throughout the arteries, significant heart muscle weakness, or diabetes. Stenting works well for less complex blockages, though repeat procedures are needed more often than with bypass surgery. For moderate- and high-risk patients, bypass surgery has been associated with a 30% to 50% reduction in mortality risk at five years compared to medication alone.
Lifestyle Changes and Cardiac Rehab
Regardless of whether you take medication or undergo a procedure, lifestyle changes form the foundation of CAD management. Many people with CAD are referred to cardiac rehabilitation, a structured program that combines supervised exercise with risk factor management and psychological support.
The physical activity goal in cardiac rehab is at least 150 minutes per week of moderate-intensity exercise or 75 minutes per week of vigorous-intensity exercise. Dietary recommendations emphasize vegetables, fruits, whole grains, fish, legumes, nuts, and healthy oils while limiting sweets, sugary drinks, and red meat. Patterns like the Mediterranean diet and the DASH diet (originally developed for blood pressure) are commonly recommended.
Quitting smoking, managing stress, and controlling blood sugar if you have diabetes are all critical pieces of the picture. These changes won’t reverse existing plaque, but they can slow its progression and reduce the risk of a heart attack or other complications.
Complications of Untreated CAD
The most serious complication of CAD is a heart attack, which happens when a clot fully blocks a coronary artery and part of the heart muscle begins to die from lack of blood flow. This is a life-threatening emergency.
Over years, CAD can also weaken the heart in less dramatic but equally serious ways. Chronic reduced blood flow forces the heart to work harder, which can lead to heart failure, a condition where the heart can no longer pump blood efficiently. CAD also raises the risk of abnormal heart rhythms, including atrial fibrillation, and in severe cases, cardiac arrest, where the heart suddenly stops beating.