Coronary Calcium Score: What CT Scans Reveal About Plaque Buildup in Your Arteries

Most people don’t know their arteries are quietly clogging up years before they feel any chest pain or shortness of breath. That’s where a coronary calcium score comes in - a simple, non-invasive CT scan that shows exactly how much calcified plaque is building up in your heart’s arteries. It doesn’t require needles, dye, or fasting. You lie down, hold your breath for 10 seconds, and in under five minutes, you get a number that tells you more about your heart risk than most blood tests ever could.

What the Score Actually Measures

The coronary calcium score doesn’t measure blood flow or blockages. It measures calcium. And calcium doesn’t just appear out of nowhere - it’s a sign that plaque has been forming for years. When fatty deposits (plaque) build up inside your coronary arteries, your body tries to repair the damage by laying down calcium. That’s what the CT scan picks up. It’s like finding rust on a pipe - it doesn’t mean the pipe is fully clogged yet, but it tells you the problem started long ago.

This test uses a special type of CT scanner - either multidetector CT (MDCT) or electron beam CT - to take hundreds of images of your heart during a single breath-hold. The machine doesn’t need contrast dye, unlike other heart scans. Radiation exposure is low - about the same as a mammogram - between 1 and 3 mSv. The result? A single number called the Agatston Score, named after the radiologist who created it in 1990. It’s calculated by measuring the area and density of each calcium spot in your arteries.

What Your Score Means

A score of zero doesn’t guarantee you’re heart-healthy forever, but it does mean no calcified plaque has been detected yet. That’s the best-case scenario. Anything above zero? That’s evidence of coronary artery disease, even if you feel fine.

• 1-10: Minimal plaque. Low risk, but not zero. Time to pay attention to lifestyle.
• 11-100: Mild plaque. You have early disease. Your risk of a heart event is higher than most people your age.
• 101-400: Moderate plaque. This puts you in the 75% increased risk category for heart attack or stroke over the next 10 years.
• 401+: Extensive plaque. High risk. This level often means significant narrowing of arteries and calls for aggressive treatment.

Doctors don’t just look at the number alone. They compare it to others your age, sex, and ethnicity using the MESA Percentile. For example, a score of 150 might be normal for a 65-year-old man but very high for a 50-year-old woman. That’s why context matters.

Why It Beats Traditional Risk Calculators

Most doctors use tools like the Pooled Cohort Equations to estimate your heart risk based on age, cholesterol, blood pressure, and smoking status. But here’s the problem: those tools get it wrong about 20-30% of the time - especially for people in the so-called “intermediate risk” group.

That’s where the calcium score changes everything. Studies show it reclassifies risk in 40-50% of people who were previously labeled as “moderate risk.” Some are told they’re low risk - but their score is 300. Others are told they need statins - but their score is zero. In one study published in JAMA Internal Medicine, calcium scoring helped identify 35% of patients who should have been on statins but weren’t.

It’s not magic. It’s physics. The scan sees the actual damage in your arteries. Blood tests guess. This one shows.

What It Can’t Do

Here’s the catch: calcium scans only see calcified plaque. About 20-30% of plaque is soft - not yet hardened with calcium. That kind of plaque can still rupture and cause a heart attack, but it won’t show up on this scan. That’s why a normal score doesn’t mean you’re safe forever. If you have high cholesterol, smoke, or have diabetes, you still need to manage your risk.

For people with kidney disease, calcium can build up in arteries for reasons unrelated to heart disease. That can make the score misleadingly high. That’s why doctors don’t recommend this test for everyone - only those with intermediate risk and no symptoms.

Who Should Get Tested?

The American College of Cardiology and American Heart Association recommend this scan for adults aged 40-75 who are at intermediate risk - meaning a 7.5% to 20% chance of a heart event in the next 10 years. That includes people with:

• High LDL cholesterol (160 mg/dL or more)
• High blood pressure
• Smoking history
• Family history of early heart disease
• Diabetes

It’s not for people with symptoms like chest pain, shortness of breath, or known heart disease. Those patients need different tests. And it’s not for young, healthy people with no risk factors - their score will almost always be zero, and the test won’t add value.

What Happens After the Scan?

If your score is zero? Keep doing what you’re doing - eat well, move, don’t smoke. But keep checking in with your doctor.

If your score is above 100? That’s when things get serious. Most cardiologists will recommend:

• High-intensity statins if your score is above 300, regardless of other risk factors
• Medication to control blood pressure and cholesterol
• Lifestyle changes - diet, exercise, quitting smoking - as non-negotiable

One patient from Reddit, age 52, had a score of 142 - higher than 78% of men his age. He’d ignored his doctor’s advice to take statins for years. After seeing the number, he quit smoking and started medication. “It scared me into action,” he wrote. That’s the power of this test. It turns abstract risk into a concrete number you can’t ignore.

Insurance and Cost

Here’s the frustrating part: insurance doesn’t always cover it. Medicare doesn’t pay for it as part of the Annual Wellness Visit. Some private insurers will cover it if your doctor says it’s medically necessary - but others won’t. Out-of-pocket costs range from $100 to $300, depending on where you live and which facility you use.

A 2023 survey found that 41% of commercially insured patients had to pay part or all of the cost themselves. That’s a barrier for many, especially since the test can prevent expensive heart attacks down the line. In the U.S., about 2.1 million scans were done in 2022 - up 17% from the year before - but only 15% of eligible patients actually get tested.

The Future of Calcium Scoring

Technology is making it better. New AI algorithms can cut radiation exposure by 40% without losing image quality. Research is underway to define exact thresholds for when to start or increase medications based on the score. The NIH is funding a 10,000-person study to determine if using calcium scores to guide treatment can actually reduce heart attacks.

More cardiologists are pushing for wider use. In a 2023 survey, 87% said they’d recommend it more often if insurance coverage improved. The European Society of Cardiology now recommends it as a first-line test for people with a family history of early heart disease.

This isn’t just a test. It’s a turning point. For people who’ve been told they’re “fine” by traditional checks, it’s a wake-up call. For others, it’s confirmation that their lifestyle changes are working. And for doctors, it’s a tool to stop guessing and start treating with precision.

What to Do Next

If you’re between 40 and 75 and have even one risk factor - high cholesterol, smoking, high blood pressure, or a family history - talk to your doctor about a coronary calcium scan. Don’t wait for symptoms. Don’t assume your blood work is enough. Ask: “Could a calcium score help me understand my real risk?”

If you’ve already had the test and your score was above zero, don’t panic. Use it as a roadmap. Work with your doctor to lower your score over time. Statins, diet, exercise, and quitting smoking can slow or even reduce plaque buildup. The goal isn’t to erase the score - it’s to stop it from getting worse.

Heart disease doesn’t announce itself. But your arteries do. And now, with a simple scan, you can hear what they’re saying before it’s too late.