Circle Cardiovascular Imaging vs Heartflow (2026)
Heartflow is a cloud service built around coronary physiology; Circle is imaging software a hospital runs itself. Heartflow's FFRCT, first authorized in 2014 and validated in the prospective HeartFlowNXT study, estimates which lesions limit flow, and its Case Analysts work each model before results return to PACS. Circle's cvi42 quantifies coronary plaque on premises with editable machine learning contours (K251027), and also reads cardiac MR, structural heart and electrophysiology planning studies. If lesion level physiology is the decision, start with Heartflow. If you want plaque analysis on your own hardware, across more than coronary CT, start with Circle.
- Patient data must stay on site: cvi42 runs on hospital hardware, and its models are locked and do not learn from customer data.
- You read more than coronary CT: cvi42 covers cardiac MR, structural heart and electrophysiology planning, with StrokeSENS for acute stroke.
- You want clearances you can check: the regulatory page lists each 510(k) number and registrations in 21 other jurisdictions.
- Physiology is the decision: FFRCT estimates the physiological significance of each lesion, validated against invasive FFR in the prospective HeartFlowNXT study.
- You want trial evidence: the PRECISE randomized trial, the ADVANCE registry and the DECIDE registry of about 22,000 patients.
- You want the work done for you: trained Case Analysts work on each model, and results return to PACS and the record.
This comparison is published by AI Health Index, an independent research platform that compares healthcare AI vendors objectively. Circle Cardiovascular Imaging and Heartflow are each graded against the same capability taxonomy, from each vendor's own public materials and the regulatory record, under the AI Health Index verification standard. No vendor pays for placement, and no vendor has reviewed this page. How this evidence is graded
Plain facts
| Fact | Circle Cardiovascular Imaging | Heartflow |
|---|---|---|
| Primary category | Radiology & Imaging AI | Radiology & Imaging AI |
| Founded | 2007 | 2007 |
| Headquarters | Calgary, Alberta, Canada | Mountain View, California, United States |
| Website | circlecvi.com | heartflow.com |
Side by Side
Select any grade to read the note behind it.
Product updates
The latest logged changes from each vendor, newest first, each linked to its source.
Circle Cardiovascular Imaging
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Product / capability
Circle Cardiovascular Imaging released cvi42 v6.5, introducing automated phase offset correction, anti-aliasing, and pre-segmentation for 4D Flow.
Source
Heartflow
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Product / capability
Heartflow PCI Navigator entered commercial use outside of clinical trials, with The Valley Hospital becoming the first U.S. institution to deploy the software.
Source
Each vendor in one paragraph
Written to be quoted whole. Each paragraph opens the AI Health Index profile of the vendor: what the product is, who buys it and what it does.
Circle Cardiovascular Imaging, based in Calgary and working in cardiovascular imaging since 2007, makes cvi42, vendor-neutral software for reading and reporting cardiac MR, cardiac and vascular CT, structural heart and electrophysiology planning, with StrokeSENS for acute stroke.
Source: AI Health Index, September 2026
Heartflow created non-invasive coronary physiology from CT. Its Heartflow One platform analyzes a coronary CT angiogram a hospital has already acquired: Roadmap Analysis for stenosis, FFRCT Analysis for the physiological significance of each lesion, simulated from a 3D model of the coronary arteries, Plaque Analysis and plaque staging, and PCI Navigator for planning intervention, now in routine use at The Valley Hospital.
Source: AI Health Index, September 2026
Questions buyers ask
How do Circle Cardiovascular Imaging and Heartflow work with the EHR?
Circle lists partner integrations on its site.
Heartflow describes CT studies sent securely to it without manual export and results returned into both PACS and the electronic record, with a support team that deploys the software and integrates it with PACS, record and other hospital systems. From the AI Health Index, drawn from each vendor's own published materials and the regulatory record, verified September 27, 2026. No vendor pays for placement.
How are Circle Cardiovascular Imaging and Heartflow priced and sold?
Circle publishes a coding and reimbursement guide and a reimbursement calculator, and describes Medicare payment for AI plaque analysis of CCTA (US$950 under Category III code 0625T, moving to a permanent Category I code from January 2026) and higher base payments for the CCTA exam.
Heartflow publishes reimbursement resources and a market access value dossier. The dossier records a Category I CPT pathway for AI plaque analysis of coronary CT, CMS payment for plaque analysis as a separate outpatient hospital service, a July 2025 EviCore coverage recommendation for Plaque Analysis, and states frankly that current reimbursement does not adequately pay for FFRCT. From the AI Health Index, drawn from each vendor's own published materials and the regulatory record, verified September 27, 2026. No vendor pays for placement.
How do Circle Cardiovascular Imaging and Heartflow handle patient data?
Circle states that image data and derived results are managed locally on a hospital workstation or customer managed server, that coronary analysis runs without sending patient data to an external reading service, and that its models are locked at integration and do not learn from customer data or from users' edits, treating each analysis in isolation.
Heartflow's trust center names encryption at rest, access monitoring, audit logging, role based access control and backups, names Amazon Web Services as its infrastructure provider, and lists AI training data and bias, AI security and AI monitoring as categories a customer can ask about, with the underlying documents released on request. From the AI Health Index, drawn from each vendor's own published materials and the regulatory record, verified September 27, 2026. No vendor pays for placement.
Which settings and specialties do Circle Cardiovascular Imaging and Heartflow cover?
For Circle Cardiovascular Imaging, the plaque module's clearance limits it to adults' cardiac CT and its validation used US data only, and the company says not all modules are available in every region. Validation by setting for the other modules is not set out on the product pages.
With Heartflow, the intended use covers adults 22 and over with suspected coronary artery disease (the combined analysis) and clinically stable symptomatic patients (FFRCT), and FFRCT's performance was validated in patients who were candidates for invasive angiography, with CT acquired within 60 days of invasive FFR. From the AI Health Index, drawn from each vendor's own published materials and the regulatory record, verified September 27, 2026. No vendor pays for placement.
Related comparisons
Other published head to head assessments involving these vendors or their closest peers. The full set for this category is on the Clinical Decision Support page.
Heartflow's Plaque Analysis and Roadmap are not cleared in Europe, the UK, Australia, Canada or Japan. Circle notes that not every cvi42 module is available in every region, and its plaque clearance reports agreement without case counts. Neither vendor publishes a price.