Pulmonary Clot Thrombectomy Has Lasting Benefits

PHOENIX -- Hemodynamic and symptomatic benefits of mechanical thrombectomy for acute intermediate- to high-risk pulmonary embolism (PE) persisted to 6 months, the FLASH registry showed.

Right ventricular (RV) systolic pressure improvements that progressively accrued in the first 30 days held steady at 6 months, with normal echocardiographic RV function and size in 95.1% and 88.2% of patients at that point, respectively.

"Perhaps more important to patients is not their RV size on echocardiography, but it's really how they feel and are they able to return back to a functional life," said Sameer Khandhar, MD, of the University of Pennsylvania in Philadelphia, in presenting the results at the Society for Cardiovascular Angiography and Interventions (SCAI) meeting here. The results were also published online in JSCAI.

Indeed, modified Medical Research Council dyspnea scores improved stepwise over time. The proportion of patients with a score of 0, indicating no shortness of breath except with vigorous exercise, rose from 12% at baseline to 41.6% at 48 hours after thrombectomy, 59.3% at 30 days and 70.3% at 6 months.

Scores on the 100-point Pulmonary Embolism Quality of Life questionnaire (PEmb‐QoL) improved significantly from a median of 9.38 at 30 days to 4.85 at 6 months (P<0.001).

"Taken together, large core mechanical thrombectomy can offer not only acute but long-term benefits," Khandhar said at the featured clinical research session. "I would really like to raise awareness and sort of challenge the field in general. Patients, they want to survive their acute PE, but they also want to be able to return toward normal life afterwards. And if there's something that we can do at the index hospitalization that gives them that opportunity, that's something that we need to continue to study."

It's all too common to see young people 3 to 6 months after PE who still can't walk or ride a bike or do the things they want to, commented David Cox, MD, past president of SCAI and moderator of a SCAI press conference. "They're alive, but their quality of life is clearly lessened," he said. "So I think that's why there's some enthusiasm to do something in the hospital."

The surrogate endpoints improved in the trial and the quality of life data fit with the clinical improvements that operators have anecdotally seen, Cox noted. "It will probably put to rest the idea if you have an intermediate PE or high-risk PE, you probably need something more than just heparin. So I think it's going to really change practice patterns."

However, he pointed to the ongoing randomized PEERLESS trial comparing the FlowTriever System against catheter-directed thrombolysis for treatment of acute pulmonary embolism as being powered for hard outcomes of mortality, major bleeding, and clinical deterioration.

That trial only includes quality of life and other endpoint assessment to 30 days.

"I think the future PE studies are really going to have to focus not only on acute outcomes, ... having patients survive, but trying to do whatever we can to prevent chronic sequela of their index PE," Khandhar emphasized.

Follow-up past 6 months would actually be better, argued session panelist Rajan A. Patel, MD, of the Ochsner Clinic Foundation in New Orleans.

"Especially in the patients who are going to have recurrent events, 6 months is usually the time where, if it's a reversible cause, you take them off anticoagulation," he said. "So it'd be nice to have at least 6 months more of data on this to see."

Nevertheless, he praised the study: "I think this is the first time we've seen quality of life metrics improve after thrombectomy."

Median dyspnea scores improved from 3.0 at baseline to 0.0 at 6 months, while 6-minute walk test distances increased from 180 m at 48 hours to 398 m at 6 months (both P<0.001).

The trial included 800 acute intermediate or high-risk PE patients treated with the FlowTriever System at 50 U.S. sites from December 2018 to December 2021. Among them, 599 completed the study at 6 months, "which I think given the time frame and the circumstances is a pretty good follow-up number of patients," said Khandhar. "Right in the middle of the study is when the pandemic occurred, which did provide some challenges for some of these functional follow-up based measurements."

Of the study participants, 8% had high-risk PE and 77% had intermediate-risk PE. Khandhar noted that 65% had concomitant deep vein thrombosis, 12.7% had systolic pulmonary artery pressures greater than 70 mm Hg during catheterization, and 32% had a contraindication to thrombolytics.

Limitations of the study included that the 6-minute walk test at 48 hours was optional, so there were low numbers.

The most common serious adverse events to 6 months were recurrent venous thromboembolism and bleeding likely from being on anticoagulation. No serious adverse events were specifically felt to be definitively related to the procedure, Khandhar noted.

"We feel this study offers the building blocks for future studies that will need to take into account not only acute outcomes, but also long term outcomes," he concluded.