LONG BEACH, California — A catheter-directed mechanical pulmonary embolism (PE) extraction system approved on April 4 by the US Food and Drug Administration (FDA) demonstrated an acceptable level of safety and effectiveness in patients with acute intermediate-risk PE, new clinical trial data show.
The Acute Pulmonary Embolism Extraction Trial with the AlphaVac System (APEX-AV) treated 122 patients with the system, which the FDA approved for the treatment of PE.
At 48 hours after the procedure, the average reduction in the right ventricle-to-left ventricle ratio was 0.45 (an average of 29.0%), with a 35.5% reduction in clot burden from baseline, said principal investigator William Brent Keeling, MD, associate professor at Emory School of Medicine, Emory University, Atlanta.
"It has a comparable safety and efficacy profile to other catheters currently on the market," Keeling said as he presented the results at the Society for Cardiovascular Angiography and Interventions (SCAI) 2024 Scientific Sessions. "We believe and we have data that this ultimately results in improved clot removal," he said.
APEX-AV was a prospective, single-arm, multicenter study of adults with acute intermediate-risk PE of < 14 days' duration that had been confirmed with CT.
The AlphaVac device (AngioDynamics, Inc.), the fourth FDA-approved catheter-directed thrombolysis device for PE, consists of a 33-French funnel and an 18-French cannula that deploys through a 22-French sheath for femoral access. It's manipulated with a manual aspiration handle, which, he said, "provides a good deal of haptic feedback." A closed waste system uses a bag to dispose of the clot.
Other Trial Outcomes
The average procedure time was "very short," said Keeling, at 37.2 ± 17.7 minutes.
Patients with hypertension had a reduction in mean pulmonary arterial pressure (mPAP) of 7.7 mm Hg; patients without hypertension had an mPAP reduction of 2.8 mm Hg, and 85% of patients had blood loss < 500 cc from the procedure.
The rate of major adverse events was 4.1% for the entire study, Keeling said, but many of the events were concentrated in the first 15 patients. After the 16th patient was enrolled, the rate dropped to 1.9%. No deaths were reported at 48 hours or at 30 days.
This procedure may have application in patients who currently don't qualify for mechanical pulmonary extraction, Keeling said in an interview.
"We see small women who come in with very distal pulmonary emboli but are in cardiac shock," Keeling explained. "And then we see younger patients come in with a large thrombosis embolic burden that's very centrally located, but they are talking and breathing normally and are hemodynamically stable. There's a disconnect between those two patients because — based on the physiology alone — the young patient with a large embolic burden would get heparin alone probably, whereas an elderly woman with multiple distal emboli would probably proceed on to some sort of escalated therapy."
This device could be an option for both types of patients, Keeling said. "Traditionally, escalated therapy or catheter-based therapy or surgery has been reserved for intermediate high-risk patients and high-risk patients, by and large," he said. "It's creeping into the low-risk intermediate patients, patients with evidence of right heart strain without serologic confirmation of muscle necrosis, and I think that ultimately, we're going to have longer-term data in terms of long-term survival and long-term exercise tolerance."
Removing the PE early on is better than leaving it, Keeling added.
Can Clinical Trials Sort Out a Crowded Field?
The AlphaVac joins a generation of PE catheters, "all relatively similar in terms of their design characteristics," said Sahil Parikh, MD, director of endovascular services at Columbia University Vagelos College of Physicians and Surgeons in New York City, after the results were presented.
"They're iterative and not disruptive," he explained. "I would argue that many of these catheters have similar features, and it is hard to distinguish one from the other." Without meaningful comparative effectiveness research, industry and local provider preference will drive their use. "Until we understand which device works better in which patients, we're really guessing about that," he said. About a dozen such devices are in the investigative phase, which could be a good thing for pricing.
"The fact that there's more competition will de facto create downward pressure on pricing, and it will potentially help health systems have access where they may not have had before, but I'm not so sure that we're there yet," he said.
A host of forthcoming comparative trials evaluating catheter-directed thrombolysis should provide some answers in the next few years. The PEERLESS trial is comparing a flow treatment device with catheter-directed thrombolysis. The HI-PEITHO trial is comparing it with anticoagulation alone. And the PE-TRACT study is comparing catheter-directed thrombolysis with anticoagulation in patients with large clots and normal blood pressure, Parikh reported.
"There is going to be an avalanche of data in the next 3-5 years," he said.