FLASH registry: Mechanical thrombectomy confers good short-term outcomes in PE
BOSTON — In patients with intermediate- and high-risk pulmonary embolism, mechanical thrombectomy was safe and linked with good short-term hemodynamic and clinical outcomes, according to data from the FLASH registry.
The cohort included 800 U.S. patients with PE (mean age, 61 years; 54% men; 76.7% intermediate-risk), of whom 32.1% had contraindications for thrombolysis. All underwent mechanical thrombectomy with a system (FlowTriever System, Inari Medical) that extracts PE thrombus by aspiration or mechanical modes without need for thrombolytics, Catalin Toma, MD, assistant professor of medicine at the University of Pittsburgh School of Medicine and director of interventional cardiology at the UPMC Heart and Vascular Institute, said at a press conference at TCT 2022.
The results were simultaneously published in Eurointervention.
“Mortality remains high in the PE space, up to 10% at 30 days in recent registries,” Toma said at the press conference. “Perhaps what’s less appreciated is the comorbidity these patients have with readmission rates, and up to 50% are still having symptoms at 6 months after their acute PE. The current guidelines don’t put a lot of emphasis on advanced therapies; they are reserved for patients who ... have a contraindication to lytics or failed therapy. The problem with the lytic approach upfront is the risk of bleeding and the requirement for ICU stay. The mechanical thrombectomy approach can provide rapid resolution of the clot and improvement in hemodynamics without the risk of bleeding.”
The primary major adverse event endpoint — device-related death at 48 hours, major bleeding at 48 hours and intraprocedural device- or procedure-related events — occurred in 1.8% of patients, Toma said, noting there were no deaths, 11 major bleeds and three intraprocedural device- or procedure-related events.
The rates of all-cause mortality were 0.3% at 48 hours, 0.8% at 30 days and 5% at 6 months, he said.
The 30-day mortality rate was far lower than that observed in the PERT Consortium Quality Database and in a meta-analysis of catheter-directed thrombolysis studies, Toma said.
He added the rates of 30-day readmission were 6.2% for any cause, 1.4% for something related to the PE treatment and 4.8% for something unrelated to the PE treatment. This was far lower than that observed in the PERT Consortium, he said.
During the procedure, pulmonary artery pressure dropped a mean of 7.6 mm Hg, or 23% (P < .0001), while cardiac index increased by a mean of 0.3 L/min/m2, or 18.9% (P < .0001), according to the researchers.
More than half (62.6%) of patients required no overnight ICU stay.
At 48 hours, the right ventricle/left ventricle ratio on echocardiography declined from 1.23 to 0.98 (P < .0001), and the improvement continued through mean latest follow-up of 105.2 to 116.3 days, according to the researchers.
The percentage of patients with severe dyspnea dropped from 66.5% at baseline to 15.6% at 48 hours, Toma and colleagues found.
“The FLASH registry demonstrates the excellent safety profile of the FlowTriever System in a real-world PE population,” Toma said at a press conference. “These are patients who based on their baseline characteristics have high risk. Nevertheless, mortality remained less than 1% at the 30-day visit. Most importantly, hemodynamics improved rapidly during the procedure and clinical recovery continued for 6 months.”
Randomized controlled trials, including PEERLESS, are planned, he said.
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We have seen interim data cuts from this registry before. The final data resemble closely what was seen in the prior data cuts, and convey that this thrombectomy technique is very safe. The safety numbers have been consistent with our experience and are perhaps better than what we would have expected. The on-table hemodynamic changes that were described are also consistent with my experience. That is important to cardiologists, especially, who live and die by pressure gradients and cardiac output indices of RV function.
What remains up in the air is what are the long-term benefits. We think that resolving pulmonary arterial obstruction is important for long-term outcomes, but we don’t have any proof of that. The numbers in the study are relatively low, but are consistent with our expectation for this patient population. We all agree that this is a large, robust, core lab-controlled dataset that gives us confidence. It shows very good safety and acute efficacy. The question remains as to what the long-term benefits are. We think we are doing the right thing, and you can make the argument that if it is safe, it is worth a shot , because the consequences of not succeeding are very significant to this patient population. It remains an open question as to in whom should we do this vs. conventional medical therapy, what is the long-term benefit and whether there is a long-term risk. The risk question is relatively well-answered. The benefit question remains open.
The guidelines are not going to change until the randomized controlled trials come back. And there are two important ones. The first is HI-PEITHO, which is examining the more fundamental question of whether something like catheter-directed thrombolysis (Ekos Endovascular System, Ekos Corp.) is better than medical therapy in the form of anticoagulation . The second is PEERLESS, which is designed to compare broadly defined catheter -directed thrombolysis against mechanical thrombectomy with the FlowTriever. It is looking at endpoints that are mixed between cost-effectiveness outcomes, patient-centered outcomes and clinical outcomes. There will be interesting findings from both of those studies, which will be good news for this field, which has been bereft of any good randomized data until now. But they are not yet ripe or ready for publication. It is going to take those studies to move guidelines. I am hopeful that those results will move us toward invasive therapy for this complicated patient population.
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Toma C, et al. Late-Breaking Clinical Science in Vascular Disease and Hypertension: Session III, in Collaboration With the Journal of the American Medical Association. Presented at: TCT Scientific Symposium; Sept. 16-19, 2022; Boston (hybrid meeting).
