By Brad Perriello and Mark Hollmer
HeartFlow yesterday said it won de novo clearance from the FDA for its non-invasive cloud-based cardiac imaging technology, which CEO Dr. John Stevens told MassDevice.com is the "most spectacular" innovation he’s seen during his 30 years in the medical device space.
HeartFlow’s FFRCT platform is an imaging approach that helps physicians treat coronary artery disease by getting a detailed look at the extent of blockage and blood flow.
"I’ve been in the medical device world for a long time, and without a doubt this is the most spectacular application of science and engineering that I have seen in my almost 30 years in the field," Stevens told us recently.
The FFRCT technology works by taking the data from a standard CT scan and applying algorithms that result in a color-coded 3D "map" detailing the changes in flow across coronary lesions, Stevens told us.
"The real genius is the application of computational fluid dynamics to human physiology. We take the data from the CT scan in the standard DICOM format. Using our proprietary process and algorithms, we extract a quantitative assessment and then map, in 3 dimensions, the entire heart and the epicardial vessels and then essentially solve the equations of flow and are able to get flow, pressure, velocity, subsequently fractional flow reserve derived from the physics of blood flow," he explained. "We can accurately model the changes in flow that occur across lesions in the coronary arteries.
Plans call for launching FFRCT over the next several months at a small group of "premier" sites in the U.S. in order to figure out best practices for adoption of the technology at various kinds of medical facilities, Stevens said today via email to MassDevice.com. Following, edited for clarity, is a transcript of our chat with Stevens:
MassDevice.com: Can you tell us what the FFRCT device is designed to accomplish?
Dr. John Stevens: The fundamental clinical question that is asked 10s of millions of times per year in doctors’ offices is, "Does my patient have coronary disease, and if so, what shall I do about it?"
In an attempt to answer that question, 1st a thorough history is taken and a physical exam. Then, quite often, if they have enough suspicion, the physician says, "I better get a test." The 1st-line tests include exercise treadmill tests, stress echos, nuclear-medicine myocardial-perfusion studies, or SPECT studies. Those are the most common in the U.S.; somewhere a little north of 20 million of those every year in the U.S., that’s the ballpark number.
Yet, even with the vast majority of patients who present for elective invasive coronary angiography having had 1 of those tests, the prevalence of normal caths is very high, north of 60% in the Dr. Manesh Patel article in the New England Journal of Medicine in 2010. The prevalence of a physician getting a negative test, yet overruling it on clinical grounds, and then finding significant disease is also high.
So in an attempt to solve that problem, we have come up with a non-invasive solution to approximate or mirror invasive fractional flow reserve, which I’m sure you know well and is unequivocally the gold standard for determining the fundamental answer to those 2 questions.
MassDevice.com: How do you use the CT analysis to compute FFR without actually being inside the heart and measuring the flow?
Dr. John Stevens: That is spectacular. I’ve been in the medical device world for a long time, and without a doubt this is the most spectacular application of science and engineering that I have seen in my almost 30 years in the field. The real genius is the application of computational fluid dynamics to human physiology.
We take the data from the CT scan in the standard DICOM format. Using our proprietary process and algorithms, we extract a quantitative assessment and then map in 3 dimensions the entire heart and the epicardial vessels and then essentially solve the equations of flow and are able to get flow, pressure, velocity, subsequently fractional flow reserve derived from kind of the physics of blood flow in a high-performance computing environment. We can accurately model the changes in flow that occur across lesions in the coronary arteries.
It really is amazing. This is a little bit colloquial, but the Arthur C. Clarke quote that Steve Jobs used many years ago: "Sufficiently advanced science is indistinguishable from magic."
It really is true. I mean, people just look at this and say, "It’s not possible. It’s a black box," or, "You really can’t do that." Well, you really can. It’s just physics. Now, it’s physics with really hard equations that can’t be solved without a supercomputer or a high-performance computing environment, but it’s physics. It’s conservation of momentum. It’s conservation of mass, simply applied to a fluid.
MassDevice.com: What were the results of the clinical trials you used to back the de novo application?
Dr. John Stevens: We have had a robust set of clinicals. We’ve done 3 pivotal trials. Our last trial with our current generation of software, which we’re using commercially and was the basis for our de novo clearance, is called the NXT trial. That was published in the Journal of the American College of Cardiology in January of 2014, which was very, very attractive improvements over CT alone. Or the data showed, in that article, even superiority over invasive coronary angiography for the depiction of vessel-specific ischemia.
MassDevice.com: Turning to the financial backing behind the company, you’ve enjoyed a lot of venture backing. Can you tell us how much you’ve raised to date and whether you’re still out there on the fundraising trail?
Dr. John Stevens: We’ve been very fortunate with an extraordinary syndicate of investors, financial and strategic. We’re very well-financed; we’ve raised about $130 million. We have an enviable cushion of cash in the bank. With that said, we always are talking to strategic and financial investors and looking at options to build and grow this into what we hope to be a very substantial company.
MassDevice.com: Are there other applications for this technology, maybe in the peripheral vasculature or other areas of the body?
Dr. John Stevens: Our first real target is expanding indications in the coronary field. We really are laser-focused because of the magnitude of the problem and, really, the lack of diagnostic accuracy that’s currently available in the non-invasive paradigms for the clinician. So what we hope to do is expand the indications and the clinical utility of what we do to really be the optimal solution whenever the clinician has the question that I raised at the very beginning. Our hard pursuit is to be the gold standard, absolute standard of care in that clinical space.
With that said, [co-founder & CTO] Charlie Taylor and [co-founder & medical affairs senior vice president] Dr. Chris Zarins, in their work over the almost 2 decades before they left Stanford and brought the technology with them to HeartFlow, spent a lot of time developing and perfecting these applications in the aorta, in the aorto-iliacs, in the peripherals, in the pulmonary vasculature and other spaces, which are frankly simpler because the image resolution is easier. The image acquisition is easier. It’s just a little simpler to do those things.
MassDevice.com: What about transcatheter aortic valve implantation?
Dr. John Stevens: I’m not sure TAVI is a good application. I’ll tell you why: Because I think the tools are so good in TAVI, and relative to the size of the markets that we’re talking about, I suspect there are 2 orders of magnitude more patients that are afflicted with coronary artery disease or the question of that than those who are going to undergo TAVI at the peak of its clinical application in the years to come.
MassDevice.com: What’s your value proposition for lowering healthcare costs?
Dr. John Stevens: Actually, we now have 2 publications, 1 in Clinical Cardiology with lead author Dr. Mark Hlatky, the chairman of health policy & research at Stanford. First of all, if you look at his editorial in the Journal of the American Medical Assn., he wrote a critical editorial of cardiac imaging, cardiac CT specifically, saying that we’re really doing a lot of excess imaging, and we’re not getting a bang for the buck, and the patients are not getting significant benefit. He then looked at our technology, our clinical data, and then using his model, applying it to the Medicare database, came up with a very different conclusion, which is HeartFlow enables a marked reduction in healthcare spend.
To give you an example, in his paper, he said, "Let me just take 100 indicative patients in the Medicare database undergoing elective catheterization. No matter what you’ve spent before you got here, let’s just ignore that. Let’s just say at the day of the index procedure, stop. Everybody gets a CT. Everybody gets a HeartFlow if they have coronary artery disease, and then let’s see what happens."
What falls out from those 100 patients that would have had an invasive coronary angiogram is that it decreased to 51 patients who actually underwent an invasive coronary angiogram. The rate of projected complications was reduced by almost 10%, deaths and complications, and the cost savings was over $3,000 per patient in Medicare dollars.
A very similar analysis was just published in Cardiovascular Intervention & Therapeutics by some leading Japanese cardiologists and Japanese health economists. Again, it’s a modeled exercise. It’s not a prospective data acquisition, but a very rigorous thinker and certainly esteemed health economist, who’s not typically friendly to new technology, had a very attractive economic assessment.