What is a Cardiac CT Scan?
A Cardiac Computed Tomography (CT) scan is a non-invasive test that uses specialized X-ray technology to produce detailed, cross-sectional 3D images of your heart and its blood vessels.
This scan allows doctors to detect a range of heart conditions, most notably the buildup of plaque in the coronary arteries. There are two main types:
- Coronary Calcium Scan: This test measures the amount of calcified (hardened) plaque in your heart's arteries. The result is given as a "calcium score."
- Coronary CT Angiography (CTA): This more detailed scan uses an iodine-based contrast dye. The dye highlights the arteries, allowing doctors to see both calcified and "soft" (non-calcified) plaque, as well as any narrowing (stenosis) in the vessels.
The Process: What to Expect
The procedure is quick and painless, typically taking only 10 to 30 minutes.
Preparation
- You may be asked to avoid eating for a few hours and caffeine for 24 hours before the scan (as it can increase your heart rate).
- Your doctor may give you a beta-blocker medication right before the test to slow your heart rate, which allows for clearer images.
The Procedure
- IV & Electrodes: If you're having a CTA, a nurse will place an IV line in your arm for the contrast dye. Small ECG electrodes will be placed on your chest to monitor your heart.
- The Scan: You will lie on a table that slides into the center of a large, donut-shaped CT scanner.
- Hold Your Breath: The machine will rotate around your body. You'll need to lie very still and will be asked to hold your breath for short periods (about 10-15 seconds) at a time.
- Contrast Dye (for CTA): When the dye is injected, it's normal to feel a temporary warm sensation or a metallic taste in your mouth.
After the scan, you can resume normal activities. You'll be encouraged to drink plenty of fluids to help flush the contrast dye from your system.
Why Is a Cardiac CT Scan Needed?
- To Assess Risk: A calcium scan is one of the best tools to determine your future risk of a heart attack.
- To Diagnose Coronary Artery Disease (CAD): A CTA is a first-line test for investigating chest pain, as it can directly see plaque.
- To Evaluate Heart Structure: It can assess the heart chambers, valves, and large blood vessels.
- To Plan for Procedures: It's used to plan for surgeries like valve replacements.
Understanding Your Results
1. The Coronary Calcium Score
This score tells you the amount of hardened plaque in your arteries.
| Calcium Score | What It Means | Risk Level |
|---|---|---|
| 0 | No calcified plaque | Very Low Risk |
| 1 - 100 | Mild plaque buildup | Mildly Increased Risk |
| 101 - 400 | Moderate plaque buildup | Relatively High Risk |
| > 400 | Extensive plaque buildup | High Risk |
Normal Artery
Stenosis (Plaque)
2. Coronary CTA (Stenosis)
The CTA looks for stenosis, or narrowing of the artery, from any plaque (soft or hard). A "normal" CTA means the arteries are clear. An "abnormal" result will describe the percentage of blockage in a specific artery, which is crucial for explaining symptoms like chest pain.
How Doctors Provide Treatment
The treatment plan is highly personalized based on your score, symptoms, and risk factors.
- Lifestyle Modifications: This is the first and most critical step for any level of plaque. This includes a heart-healthy diet, regular exercise, and quitting smoking.
- Medications: For a calcium score over 100 or plaque on a CTA, statins (to lower cholesterol) and low-dose aspirin (to prevent clots) are often recommended.
- Further Testing: If a CTA shows significant narrowing, your doctor may order a stress test to see if it's limiting blood flow.
- Procedures: For severe blockages causing symptoms, procedures like angioplasty (stenting) or bypass surgery (CABG) may be necessary.
The Most Important Takeaway: A Cardiac CT scan is an incredibly powerful tool for prevention. It can find heart disease years before a heart attack happens, giving you time to manage it with lifestyle changes and medication.