Plaque buildup is the gradual accumulation of fat, cholesterol, calcium, and cellular debris inside your artery walls. Over time, these deposits harden and narrow the space blood flows through, a process called atherosclerosis. It’s the underlying cause of most heart attacks and strokes, and it typically develops over decades without any noticeable symptoms.
How Plaque Forms in Your Arteries
Plaque buildup doesn’t happen overnight. It starts when something damages the inner lining of an artery. High blood pressure, smoking, high blood sugar, and high cholesterol are the most common culprits. Once that lining is damaged, LDL cholesterol (the “bad” kind) seeps into the artery wall and gets trapped.
Your immune system treats this trapped cholesterol as a threat. White blood cells rush in to absorb it, but they become bloated and die in the process, forming what’s called a fatty streak. This is the earliest stage of plaque, and it can begin in childhood or adolescence. Dead cells and debris keep piling up, and the fatty streak grows into a larger mass of plaque. Your body then builds a fibrous cap over it, made of smooth muscle cells, to keep pieces from breaking off into the bloodstream.
As the plaque grows, it narrows the artery’s opening, leaving less room for blood to pass through. This narrowing can restrict blood flow to the heart, brain, kidneys, or legs depending on which arteries are affected.
What Plaque Is Made Of
A mature plaque is mostly cholesterol, both in its free form and bound to other fats. In carotid artery plaques (the arteries in your neck), cholesterol makes up about 75 milligrams per gram of dry tissue. More than half of that cholesterol sits in its unprocessed, free form rather than the packaged form your body normally transports. The rest of the plaque consists of calcium deposits, dead immune cells, scar tissue, and fibrous material. Over years, calcium hardens portions of the plaque, which is why doctors can detect it on imaging scans.
Stable vs. Dangerous Plaques
Not all plaques are equally dangerous. The size of a plaque matters less than its structure.
Stable plaques tend to have thick fibrous caps, heavy calcification, and relatively small cores of dead material. They narrow the artery gradually and may limit blood flow, but they’re less likely to cause a sudden heart attack. Many people live with stable plaques for years.
Vulnerable plaques are the ones that kill. These have thin fibrous caps (65 micrometers or less, thinner than a human hair), large pools of dead cells and cholesterol at their core, and heavy infiltration by immune cells that actively break down the cap from within. When a vulnerable plaque ruptures, its contents spill into the bloodstream and trigger a blood clot. That clot can block the artery entirely in seconds, cutting off blood supply to the heart or brain. Internal bleeding within the plaque itself can also rapidly expand the dead core, making rupture more likely.
This is why someone with only moderate narrowing can have a heart attack while someone with severely narrowed arteries may not. The composition of the plaque, not just its size, determines the risk.
Why Symptoms Show Up Late
Plaque buildup is notoriously silent. Arteries can lose a significant portion of their internal diameter before you feel anything, because the body compensates by rerouting blood flow and widening the artery itself. Carotid artery disease, for example, often causes no symptoms until the blockage is severe. Many people discover they have significant plaque only after a heart attack, stroke, or routine screening.
When symptoms do appear, they reflect which arteries are affected. Plaque in the coronary arteries (supplying the heart) can cause chest pain or pressure during exertion, shortness of breath, or fatigue. Plaque in the carotid arteries may cause mini-strokes with temporary vision loss, numbness, or slurred speech. Plaque in the leg arteries causes cramping or pain when walking that goes away with rest.
How Doctors Measure Plaque
A coronary calcium scan is one of the most common ways to assess plaque buildup. It’s a quick CT scan that measures how much calcium has deposited in your heart’s arteries, producing a number called a calcium score.
- Score of 0: No detectable calcium. Low chance of a heart attack in the near future.
- Score of 1 to 99: Mild plaque deposits are present.
- Score of 100 to 300: Moderate plaque deposits, associated with a relatively high risk of heart attack or other cardiovascular events over the next three to five years.
- Score above 300: Extensive plaque disease and a higher heart attack risk.
Scores at or above the 75th percentile for your age and sex carry a significantly elevated risk. Your doctor may also use blood tests (cholesterol panels), stress tests, or ultrasound of the carotid arteries to get a fuller picture.
What Drives Plaque Buildup
LDL cholesterol is the primary fuel. The more LDL circulating in your blood, the more likely it is to penetrate and accumulate in artery walls. Current guidelines from the American Heart Association set clear targets: LDL should be below 100 mg/dL for people at borderline or intermediate cardiovascular risk, and below 70 mg/dL for those at high risk. People who have already had a heart attack or stroke and are at very high risk should aim for below 55 mg/dL.
Beyond cholesterol, the major accelerators are high blood pressure (which damages artery linings), smoking (which triggers inflammation and makes LDL more likely to oxidize and stick), diabetes (which raises blood sugar and promotes artery wall damage), obesity, chronic inflammation, and a sedentary lifestyle. Family history plays a role too. Some people produce too much LDL or clear it too slowly because of their genetics, putting them at risk even with otherwise healthy habits.
Slowing and Reducing Plaque
Once plaque is present, it doesn’t simply vanish, but aggressive cholesterol lowering can stabilize it and, in some cases, modestly shrink it. Statins and other cholesterol-lowering medications work primarily by reducing the amount of LDL available to feed the plaque. They also appear to strengthen the fibrous cap over existing plaques, making rupture less likely. Driving LDL well below 70 mg/dL has been shown to shift plaques from vulnerable to stable.
Lifestyle changes remain the foundation. Regular aerobic exercise (at least 150 minutes per week of moderate activity), a diet low in saturated fat and rich in vegetables, fruits, whole grains, and healthy fats, not smoking, maintaining a healthy weight, and managing blood pressure and blood sugar all slow plaque progression. These interventions are most effective when started early, before extensive deposits form, but they provide benefit at any stage.
For people with severe narrowing that causes symptoms, procedures like stenting (placing a small mesh tube to hold the artery open) or bypass surgery can restore blood flow. These don’t cure the underlying disease, though. Without ongoing cholesterol management and lifestyle changes, new plaque will continue to form.
Dental Plaque Is a Different Process
The term “plaque buildup” also refers to the sticky film of bacteria that forms on teeth. Dental plaque is a biofilm: bacteria attach to a thin protein layer on tooth surfaces within hours of brushing. Early colonizers like certain streptococcus species anchor first, then more complex communities layer on top. If not removed by brushing and flossing, dental plaque hardens into tartar (calculus) that can only be removed professionally. Left unchecked, it leads to cavities and gum disease. While the word “plaque” is the same, dental plaque and arterial plaque are completely different substances driven by completely different processes.