Inari Medical Interim "Flash" Study Re

Inari Medical released interim data from it’s Flash study that looks at the effectiveness of the FlowTriever, mechanical clot removing tool. The data looks pretty good to me. Inari is up 3.7% on the news. Here’s some of the key points:

At 48 hours post procedure, the major adverse event rate and mortality rate were low, at 1.4% and 0.2%, respectively. None of the deaths or major adverse events were device related.

The outcomes were achieved while limiting utilization of hospital resources, with less than 4% of patients receiving adjunctive therapy and a median of 0 days in the ICU post procedure.…

This is compared to a death rate of diagnosed and treated PE at 8% (Cardiology Review Article).

I am no doctor (and I would love to hear any doc’s point of view on this study), but it seems to me that the FlowTriever would have to be prohibitively expensive for this not to gain wide use.

I’m probably going to pick up a few shares and get restarted, but I’d like to hear from the medical community in case there’s something that I’m missing.





This is not my endorsement or rejection of Inari, I just want to point out one thing:

Never, ever take the rosy headline of a biotech or medical device company’s trial results at face value.
You have to read every damn thing yourself and do your own research.
I’d like to think that this approach applies to EVERY stock we want to put in our portfolio, but I feel it is doubly true in the biotech/medical device sector.

Which is why I don’t bother investing in them - it’s just too much work, paired with heightened degrees of risks that other sectors don’t typically face, especially if you’re not highly attuned to the industry (I’m only boarded in internal medicine, so perhaps, if I had trained in heme-onc or some other specific fellowship, I’d have a greater inclination to go biotech stock picking).

To illustrate what I mean for Inari here:

The review article you posted says the death rate of diagnosed and treated PE is 8%.
Well, you can’t really compare that to Inari’s reported death rate of 0.2%.

  1. Inari’s reported 0.2% death rate in the headline is for 48 hours post procedure. Looks great, but the death rate should be higher the farther out you look post-procedure, whether it’s 30 days, 90 days, 1 year, etc.
    Well, the review article doesn’t specify but I highly doubt the cited 8% death rate put a cut off at 48 hours after presentation. It’s probably not comparable at all by this metric alone.

  2. You should read Inari’s FLASH trial criteria:
    There is huge selection bias (as there always will be, for any procedure or medical device trial). Inari deliberately excludes patients expected to live less than 30 days. That’s going to massively deflate their death rate figures.
    A lot of patients who die of a PE despite usual diagnosis and treatment, are going to fall into this category of life expectancy less than 30 days.
    The patients nearest their end of life are often those with terminal cancer, already sick with major comorbidities in the ICU, etc and these are the patients who are most likely to get a massive PE and not survive, no matter what you do to them.
    So, that 8% death rate in the review article isn’t going to exclude these sickest of the sick; it’s not fair to compare with Inari in this manner either.

  3. Inari’s FLASH trial criteria also exlcudes patients whose “imaging evidence that suggests, in the Investigator’s opinion, the subject is not appropriate for mechanical thrombectomy intervention”.
    That’s more selection bias. The 8% review article death rate is not going to exclude those patients who can’t be helped with mechanical thrombectomy.

Again, I don’t know anything about Inari other than taking the couple minutes to look at the links you posted and a quick search to find Inari’s trial link, but I hope it makes sense to you why you can’t just immediately trust company headlines. A better way to find out if their device is “better” is to do a comprehensive review of all of Inari’s mechanical thrombectomy competitors’ trials and see if Inari really does beat the pack in the relevant endpoints, and if so, does their device costs make sense for hospitals to switch to using them.

Off the top of my head, I know the hospitals I work at uses Penumbra products for mechanical thrombectomy, so I would at minimum recommend you check their data out versus Inari.


Great post and there is big competition (ABT, BSX) on its way. The big boys in this space want some part of market and revenue. That means lower GM for NARI…

And it’s interesting that the big boys haven’t bought out NARI for small money (4-5b) instead they bought for small money……

At 48 hours post procedure, the major adverse event rate and mortality rate were low, at 1.4% and 0.2%, respectively. None of the deaths or major adverse events were device related.

This is compared to a death rate of diagnosed and treated PE at 8% (Cardiology Review Article).

The trial doesn’t seem to be against the current standard of care, so I’m not sure you can compare these two numbers. You should have a control group from the same population and give them the current standard of care and see how they do.

I worked in the space for a few years on the stroke side, not at penumbra, but a company now part of MDT, we had a mechanical clot removal device for ischemic stroke. It has been completely upended in recent years as it turns out a vacuum suction device has clinically no difference then a mechanical clot removal device for stroke, so essentially all you need is a strong catheter and a vacuum pump, not a $5k patentable disposable stent retriever that much fewer people can design and build. I’m not sure if a similar study has been done for PE, but it seems like a risk.

Acquisitions in the space typically happened at the less than $500 million level, usually you buy a company with a good idea, some positive clinical data, and limited manufacturing and marketing / sales capability. Even then, there are only 3 or 4 companies that acquired stuff, not sure about the PE side, but that is how the neuro side was. These companies don’t want to buy a company with manufacturing / marketing / sales, they already have their own.


The walk vascular JETI is a vacuum pump device:

Great information. Thanks. As for the points about competitors, I should have done some more digging on current alternative treatments. When I looked at this about a year ago, it didn’t seem like there were many alternatives other than clot busting drugs. The thoughts as too when medical device companies are purchased, was enlightening as was the use of vacuum technology.

As far as not understanding standards for medical trials, I didn’t present myself as a medical expert. I asked if anyone with a medical background would share their point of view. While I was excited about what appeared to be good data, I did asked for direct knowledge of the technology to help determine if this has merit. Maybe, “you should read the damn thing and do research for yourself” is a tad harsh for a non-medical person.