HeartFlow is a noninvasive technology that uses a standard CT scan of your heart to create a detailed 3D model of your coronary arteries and simulate blood flow through them. Instead of threading a catheter into your heart to measure whether a blockage is restricting blood flow, HeartFlow generates that same measurement from images you’ve already had taken. The result is a color-coded map your doctor can use to determine whether a narrowed artery is actually causing problems, or whether it can be safely left alone.
How the Technology Works
HeartFlow starts with a coronary CT angiography (CCTA), which is a specialized CT scan of the arteries that supply blood to your heart. This scan is already a common, widely available test. What HeartFlow adds is a layer of advanced computer analysis on top of it.
After the CT images are captured, they’re uploaded to HeartFlow’s off-site supercomputers. There, algorithms build a precise 3D geometric model of your coronary arteries and apply a physics-based technique called computational fluid dynamics to simulate how blood moves through them. The system accounts for vessel size, branching patterns, and assumptions about the resistance in smaller blood vessels downstream. The output is a number called fractional flow reserve, or FFR, calculated at every point along your coronary arteries. Doctors already rely on FFR as the standard for deciding whether a blockage needs treatment. Traditionally, getting that number required an invasive catheter procedure. HeartFlow delivers it without one.
Results are typically available within 24 to 48 hours after the scan is uploaded. Your doctor receives an interactive 3D model with a color-coded display: areas with healthy flow appear in one color, while areas with restricted flow stand out clearly.
Who It’s Designed For
HeartFlow is used for people with stable chest pain or other symptoms that suggest coronary artery disease, but whose diagnosis isn’t yet clear. The most common scenario is a patient whose CT scan shows a blockage somewhere between 40% and 90% of a coronary artery. That range is a gray zone. A 40% narrowing rarely needs intervention, and a 90% narrowing almost always does, but anything in between requires more information. HeartFlow fills that gap by showing whether the narrowing is actually choking off blood supply or whether flow remains adequate despite the visible blockage.
The 2021 chest pain guidelines from the American Heart Association and American College of Cardiology give HeartFlow a Class 2a recommendation for exactly this situation, meaning it’s considered a reasonable next step when a CT scan reveals moderate narrowing in a major coronary artery segment.
How Accurate It Is
The key clinical trial validating HeartFlow’s accuracy, called the NXT trial, tested it against the gold standard: invasive FFR measured with a pressure wire inside the artery. In 254 patients, HeartFlow achieved 86% accuracy on a per-vessel basis, with 84% sensitivity (meaning it correctly identified most flow-limiting blockages) and 86% specificity (meaning it correctly cleared most arteries that weren’t causing problems). Those numbers are strong enough to guide clinical decisions, though not perfect. In borderline cases, your doctor may still recommend additional testing.
Reducing Unnecessary Procedures
One of HeartFlow’s biggest practical benefits is keeping people out of the catheterization lab when they don’t need to be there. Invasive coronary angiography, where a catheter is guided through a blood vessel and into the heart, carries real risks: bleeding, vessel damage, allergic reactions to contrast dye, and a small chance of heart attack or stroke. It’s also expensive and requires recovery time. Yet a large number of patients who undergo this procedure turn out to have clean or non-obstructive arteries, meaning the test was unnecessary.
The PLATFORM trial measured this directly. Among patients who were referred straight to invasive angiography without HeartFlow, 73% turned out to have unobstructed arteries, meaning nearly three out of four underwent an invasive procedure they didn’t need. When HeartFlow was used first to screen patients, that number dropped to 12%, an 83% reduction. That’s a dramatic shift: it means the vast majority of patients who would have gone through an unnecessary catheterization were correctly identified beforehand and spared the procedure.
A review by the VA Health Systems Research group confirmed that HeartFlow reduces the use of invasive angiography in real-world community settings, particularly at facilities that already use CT angiography as part of their diagnostic workflow.
What the Experience Looks Like
From your perspective as a patient, the process is straightforward. You undergo a coronary CT angiography, which involves lying still in a CT scanner for several minutes while contrast dye highlights your arteries. This is a noninvasive outpatient test with no incisions, no sedation, and minimal recovery. You can typically go home right after.
Your medical team then uploads the scan data to HeartFlow for analysis. Within one to two days, your doctor reviews the 3D model and FFR results. If the analysis shows your blood flow is adequate, you may avoid further invasive testing entirely. If it reveals a significant flow restriction, your doctor has precise information about where the problem is and how severe it is, which helps plan the next step more effectively.
Coverage and Cost
HeartFlow has a dedicated billing code (CPT code 75580, effective since January 2024) and is covered by Medicare under specific clinical criteria. Private insurance coverage varies by plan and region, so it’s worth checking with your insurer before the test. The technology is available at a growing number of hospitals and cardiac imaging centers across the United States, though not every facility offers it. Your cardiologist can tell you whether it’s an option at your location and whether it fits your clinical situation.