Outcomes With Treatment Interventions for Clot-In-Transit in Patients With Pulmonary Embolism: An Interview With Sripal Bangalore, MD, MHA

Dr Sripal Bangalore shares background and insights on his JIC articles, “Outcomes With Treatment Interventions for Clot-In-Transit in Patients With Pulmonary Embolism: A Meta-Analysis” and “Comparing Upfront Catheter-Based Thrombectomy With Alternative Treatment Strategies for Clot-in-Transit.”

Transcript:

Hi, my name is Sripal Bangalore, interventional cardiologist at NYU School of Medicine. I'm also the interventional director of the PERT program at Bellevue Hospital.

00:21: What inspired your group to conduct the initial meta-analysis?

This study was mainly to look at clot-in-transit. And there are kind of two schools of thought about clot in transit, you know. One school is to say that oh, every clot, every PE, started with a clot-in-transit, except that in some we capture it and in some we don't capture it, so what's the big deal? But the other school of thought is to say, you know, we are doing echocardiogram in the select group of patients who came in for a reason, mainly shortness of breath, and then we are seeing this clot-in-transit. So, these are likely a higher risk group of patients. And, interestingly enough, what data had shown so far was that patients who have a clot-in-transit have a high risk of mortality. So, we wanted to investigate existing data as to what are the outcomes of various therapies based on published literature.

01:27: How did the results of the meta-analysis inform your choice to focus on catheter-based thrombectomy in your next paper?

So we first decided to look at what's there in the literature. So, in other words, we did a meta-analysis of all of the studies published out there, and it's interesting to note that we had some retrospective studies we had…. everything was observational to begin with and there was a combination of a retrospective studies, some small case series, case reports, etc. And all of them combined together, we only have 492, or something around that number of patients with clot-in-transit. We categorized them based on the treatment that was administered, and the common ones were anticoagulation alone, surgical embolectomy, catheter-based thrombolysis, or systemic thrombolysis, and the initial intention was to see where what were the outcomes of the patients with these 4 different therapies.

And one thing which was very interesting, and which is important to emphasize, is the overall mortality. Even if you weigh it based on the studies, it was very high, something around the order of 22%, 21% to 22% mortality, in-hospital mortality, clearly suggesting these are very sick patients.  It's not just there is just a clot there, but clearly suggesting that their mortality is increased. And we also showed that there is a graded differences in mortality among various therapies. What we showed was, if a patient had anticoagulation alone, the mortality was very high, something to the order of around 35%, and for with other therapies the next highest mortality was surgical embolectomy, followed by CBT, and finally systemic thrombolysis. So, clearly suggesting we need to do something different, but just giving them unfractionated heparin alone may not be the way to treat these patients because their in-hospital mortality is very high.

03:52: Do you have plans to focus on any of the remaining 3 interventions in the future? Why or why not?

Based on this study, our intention, I mean, it was surprising to note that the catheter-based therapies, you know in our clinical practice we've been using catheter-based therapies for a couple of years, mainly mechanical thrombectomy in these patients. What we have noticed, what we noted in the literature search was that the proportion of patients, the number of patients who had catheter-based therapies were very small, because catheter-based therapies tend to be a newer approach, and it was only, I think, 29 patients in that series underwent catheter-based thrombectomy. So, you know we had wide confidence interval for the mortality estimates around that. So, our question next is to say, how do catheter-based therapies, if you had more numbers, stack up to whatever we see in the literature? So, we looked at some of that data. Interestingly enough, we have another paper which was published a couple of weeks ago in Circ Intervention, comparing catheter-based thrombectomy to anticoagulation alone. I mean, it's again a small series of 35 patients, but clearly showing the mortality is significantly reduced with catheter-based thrombectomy when you compare it to anticoagulation alone. And we also published in JIC our own series of catheter-based thrombectomy and comparing with what we found in the meta-analytic rates, and clearly showing that catheter-based thrombectomy significantly lowers, or at least it's associated with, lower mortality, potentially suggesting that there is a benefit of catheter-based thrombectomy.

05:44: Were any additional questions prompted by the data?

I think the question, after all of these, is clearly what we are currently doing as standard of care, which is anticoagulation alone, is not sufficient. So, we need to do something different. And I think we need more data, more robust data. I mean, the question is, you always say, oh, the gold standard is randomized trials. I mean, the question is, can we actually do randomized trials in this space? Because many times you see a clot-in-transit and you know, in a good proportion of cases it embolizes rather quickly. So, first of all, clot-in-transit is not as common, so given that it's rare and potentially the clot-in-transit may not be there forever, I mean, it's going to embolize, will we have any enough sample size to do a randomized trial? But we do need more data, because even with all of the series we have, it's just a couple of 100 of patients that are driving the data. So, we need more data to drive this field. And hopefully, we can have specific recommendation for patients who have clot-in-transit and also who have pulmonary emboli associated with it.

07:04: What are the key highlights that you hope cardiologists take away from your studies?

I think there are a couple of highlights that what I want to emphasize I mean, one of the things is, regardless of the treatment choice, it's important to recognize that when we see a clot-in-transit, you know, thrombus swirling around in the RA, RV, etc, clearly, all of these data suggest that the patients have a high incidence of in-hospital mortality. The meta-analytic rates were upwards of 20%; in other words, 1 in 5 patients die. So, I think that's the big take home, that it's just not a clot circling around and you can get away with it, it is associated with significant high mortality. And in terms of choice of therapies, I think it's best to make sure that if your hospitals have PERT teams, have a group discussion so that you can get the best of minds talking about it and tailor therapies that will work best for your patients.

08:14: What can we look forward to seeing next from your group?

We've already published our small series on catheter-based therapies vs anticoagulation for clot-in-transit. We are working with a larger group which is trying to combine data from multiple centers so hopefully we should have a bigger sample size and, hopefully, we can address more questions as to what is the optimal treatment for these patients.

08:40: Is there anything else you'd like to share with our audience?

The other thing I want to emphasize is, if you look at the ESC guidelines, the ESC guidelines just has a statement saying patients with clot-in-transit have a high risk of cardiovascular events, but they don't have a recommended specific treatment. Something to keep that in mind—that even the guidelines recommend that they are high risk, and we need to do something about it.