I have written fairly extensively about the management of high risk PE. Despite their growing popularity, I have remained quite skeptical of catheter directed therapies. If you are going to give a thrombolytic, my sense is that it is going to be just as effective if given through a peripheral vein, and that fancy catheters add nothing but risk and cost. Of course, that impression is based on pretty weak evidence, so I am always looking for new trials to update my opinion. Today we have 2 new PE trials: the STORM-PE and STRATIFY trials.
STORM-PE
Lookstein RA, Konstantinides SV, Weinberg I, Dohad SY, Rosol Z, Kopeć G, Moriarty JM, Parikh SA, Holden A, Channick RN, McDonald B, Nagarsheth KH, Yamada K, Rosovsky RP; STORM-PE Trial Investigators. Randomized Controlled Trial of Mechanical Thrombectomy With Anticoagulation Versus Anticoagulation Alone for Acute Intermediate-High Risk Pulmonary Embolism: Primary Outcomes From the STORM-PE Trial. Circulation. 2026 Jan 6;153(1):21-34. doi: 10.1161/CIRCULATIONAHA.125.077232. Epub 2025 Nov 3. PMID: 41183181
Methods
The STORM-PE trial is an international multicenter open-label RCT. It included adult patients with normal blood pressure and intermediate-high risk PE (which basically just meant an elevated troponin, BNP, or large RV on imaging). All patients were treated with heparin, and they were randomized to either get a “computer-assisted vacuum thrombectomy” or nothing. This “CAVT” is a novel form of mechanical thrombectomy that uses some kind of proprietary software algorithm to aspirate clot while minimizing blood loss.
Results
They enrolled 100 patients (of 767 screened). There was a statistical difference in their primary outcome, which was mean reduction of the RV/LV ratio at 48 hours.
They report no differences in adjudicated adverse events. (I feel like adjudication just adds bias in an unblinded trial).
Clinical deterioration requiring rescue therapy occurred in 1 patient in the thrombectomy group and 3 in the standard care group.
There were only 2 deaths, and both occurred in the thrombectomy group.
They report less tachycardia at 48 hours in the thrombectomy group, although that group was also more tachycardic to begin with, so there was no difference in the change in heart rate. Either way, the difference is almost certainly clinically meaningless (heart rate of 87 vs 80).
There were no recurrent PEs in either group.
My thoughts
If it hadn’t been sent to me for my thoughts, I would have ignored this paper. The RV/LV ratio is clearly not a patient oriented outcome. It is not an outcome that should ever drive clinical practice. This is the kind of research that needs to be done to determine whether there is justification for a larger RCT looking at clinical outcomes, but this is not the kind of trial that clinicians should pay attention to. At this point, with no evidence of patient oriented or clinical benefit, no one should be using this device outside of a clinical trial.
You can’t really make anything out of the ‘clinical deterioration requiring therapy’ secondary outcome. This is an unblinded trial, and you aren’t going to take a patient who just had a thrombectomy back for thrombectomy, but you will clearly have a lower bar to escalate the patients who have not yet had an intervention.
Although clearly not statistically significant, it is concerning to me that there were infinitely more deaths in the thrombectomy group (2 vs 0).
Perhaps the biggest issue with this trial was the target population. These are not the patients I would be targeting. I don’t think that troponin or BNP, in an otherwise well patient, means anything. These patients generally have fantastic outcomes, and so subjecting them to an invasive procedure makes no sense. They excluded anyone with any hint of hemodynamic instability, which is the group of patients where these interventions actually make sense. The fact that there were 0 deaths in the control group basically proves that the intervention could not possibly help this population.
Finally, this trial design could never answer the question of whether this specific “computer assisted” device provides any value. That makes sense, given that the sponsor was “involved in the study design, data collection, analysis, and interpretation, manuscript preparation, and the decision to publish.” Without a standard catheter device as a comparison group, there is no way to know whether this fancy device is better or worse. Based on the other studies I have seen, there is absolutely nothing to say that the computer algorithm added anything here, aside from cost. Allowing manufacturers to design their own trials is clearly dumb, and results in trial designs that can only act as advertisements rather than helpful science.
Conclusion
This is basically a pilot trial, looking at disease oriented rather than patient oriented outcomes. It is an unblinded trial, designed and run by the device manufacturer. Even with those biases, the results are completely underwhelming. No one should be using this device at this time.
STRATIFY
Kjaergaard J, Bang LE, Sonne-Holm E, Wiberg S, Holmvang L, Lassen JF, Sørensen R, Høfsten DE, Ulriksen PS, Jawad S, Palm P, Søe C, Ersbøll MK, Boesgaard S, Møller JE, Thune JJ, Hassager C, Tilsted HH, Lønborg J, Egstrup M, Kristiansen OP, Seven E, Lindholm MG, Eskesen K, Fanø S, Carlsen J. Randomized trial of low-dose -, ultrasound assisted thrombolysis or heparin for pulmonary embolism. Cardiovasc Res. 2026 Jan 29:cvag038. doi: 10.1093/cvr/cvag038. PMID: 41610160
Methods
The STRATIFY trial is an open label multicentre RCT that randomized adult patients with acute intermediate high-risk PE according to ECS guidelines (basically RV dilatation and elevated troponin) to one of three groups: heparin alone, heparin plus ultrasound assisted thrombolysis using 20mg of alteplase over 6 hours, or heparin plus intravenous alteplase (also 20mg over 6 hours).
Results
They included 210 patients (out of 673 screened), and the groups look relatively similar at baseline.
Unfortunately, like the prior study, their primary outcome was disease oriented: change in thrombus burden. There was a statistical improvement in the thrombus burden using a refined modified Miller score with both thrombolysis groups as compared to heparin alone, but there was no benefit of using ultrasound assisted thrombolysis as compared to just giving the dose through the peripheral IV. (Reduction in the score of 6.3 vs 6.1 vs 2.6).
At 3 months, mortality was 4.3% with thrombolysis and 0% with heparin, but not statistically different. They give us causes of death for 5 patients, and at least 3 of the 5 were bleeding related (1 GI bleeds and 2 intracranial hemorrhages).
Bleeding was higher, but not statistically so, with thrombolysis (11% vs 4%).
There were no differences in the quality of life or walk test measurements at 3 months.
My thoughts
I was excited to see this study, because most of the studies I have seen listed on clinicaltrials.gov seem to assume that a catheter is beneficial, and so only compare catheter directed thrombolysis to heparin (leaving out the intravenous thrombolysis arm). Others compare to intravenous thrombolytics, but use wildly different doses of thrombolytics, which just doesn’t make sense. This trial, using the same low and slow dose of alteplase both intravenously and through the pulmonary artery catheter is clearly the way to go, and seems to support my contention that there is absolutely no value from these catheters. If you are going to give thrombolytics, you should just give them though an IV.
Of course, this trial makes thrombolysis look bad, in my opinion. They sort of skirt over that fact, by focusing on disease oriented outcomes. However, thrombolysis did not seem to improve anything important, but seemed to result in more bleeding and more death. Not something I would choose.
As far as the disease oriented outcome is concerned, I don’t really know what changes in this score mean. It is funny that the Miller score needed to be both modified and refined. I am not familiar with this score, but I really question the validity of any score that required multiple modifications. Furthermore, I do not know what change in this score would be considered clinically important, and AI models like OpenEvidence have never even heard of the refined modified version of this score, and tell me that for the basic Miller Index no minimal clinically important difference has been established.
Like the last trial, I think they are focused on the wrong population. Troponin elevations simply catch too broad a group of patients, and RV dilatation is also not specific enough. If we are going to find a benefit, patients are going to have to be sicker. The 0% mortality in the control group sort of proves that thrombolysis was never going to helpful. I don’t think we need to wait until patients are peri-arrest, but we are going to need to find different hemodynamic criteria to identify patients who actually have a risk of dying from their PE if we are going to see any benefit from thrombolysis.
That being said, I think this approach – a low and slow dose of thrombolysis through a peripheral IV – is clearly going to be the best approach going forward. No one should be using fancy, expensive, invasive catheters until they have been proven to provide a benefit over the exact same dose of thrombolytic given through a peripheral IV. (Given that the entire blood circulation goes through the pulmonary arteries, I cannot imagine that the catheters provide any value, except to shareholders in these companies.)
Conclusion
If you are going to use thrombolysis, you should provide it through a peripheral IV, not a specialized catheter. That being said, the results don’t look good in this study, and I definitely would not be giving it in this specific population.
Overall conclusion
I don’t think either of these trials significantly changes our management of pulmonary embolism patients. In sick (hypotensive) patients, thrombolysis is a good idea. Outside of that, we are still trying to define the right population for more aggressive therapy. To date, there is absolutely no evidence that fancy devices or thrombectomy are a good idea. In the long run, based on their value in other conditions, I could imagine thrombectomy being effective, but there is about 0% chance that catheter directed thrombolysis will be more effective that systemic thrombolysis.
Morgenstern, J. Higher risk PE management updates (The STRATIFY and STORM-PE trials), First10EM, April 13, 2026. Available at:
https://doi.org/10.51684/FIRS.145360
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