Use of pharmacomechanical catheter-directory thrombolysis significantly reduced the number of pulmonary artery branches with total or subtotal occlusions in patients with acute pulmonary embolism, based on data from more than 100 individuals.
Reduced distal vascular volume is a significant predictor of 30-day and 90-day mortality in acute pulmonary embolism (PE) patients, and pulmonary obstruction is often the cause, wrote Riyaz Bashir, MD, of Temple University, Philadelphia, Pennsylvania, and colleagues.
Some studies of catheter-based treatments have shown a reduction in pulmonary artery (PA) obstruction in PE patients, but the impact has been modest, the researchers said.
“The recently published RESCUE (Recombinant tPA by Endovascular Administration for the Treatment of Submassive PE Using CDT for the Reduction of Thrombus Burden) trial showed a 35.9% reduction in PA obstruction using the Refined Modified Miller Index (RMMI), the largest reduction of all published catheter studies with core lab measurement, with similar doses of tissue plasminogen activator (tPA),” the researchers wrote.
The Bashir endovascular catheter was designed to maximize thrombus reduction via a pharmacomechanical infusion. The catheter features an expandable basket of 6 nitinol-reinforced infusion limbs.
“There are three crucial goals that we want to accomplish in patients who have a severe pulmonary embolism,” Dr. Bashir said in an interview.” Those include, in the order of importance, survival, recovery of right ventricular function, and resolution of blocked pulmonary arteries; both segmental and proximal pulmonary arteries,” he said.
Most previous studies have focused on the first two goals, but they still need to evaluate the resolution of PA blockages carefully, said Dr. Bashir.” In our clinical practice, we have seen a large number of patients who develop debilitating shortness of breath from these blockages. We decided to carefully evaluate these blockages before and after pharmacomechanical catheter-directed thrombolysis with the Bashir endovascular catheter using the core lab data from the RESCUE study,” he said.
In the current study published in JACC: Advances), the researchers used baseline and 48-hour posttreatment contrast-enhanced chest computed tomography angiography of adult PE patients with right ventricular dilatation.
The study population included 107 adults with acute intermediate-risk PE who were treated with pharmacomechanical catheter-directory thrombolysis (PM-CDT) at 18 sites in the United States. Of these, 98 had intermediate high-risk PE with elevated troponin and/or brain-type natriuretic peptide (BNP) levels and 102 had bilateral PE.
The primary endpoint was the change in the number of segmental and proximal PA branches with total or subtotal occlusions (defined as > 65%) after 48 hours compared to baseline. Occlusions were assessed using McNemar’s test.
Patients with bilateral PE received two Bashir catheters; those with unilateral PE received one catheter each.
Each patient received a pulse spray of 2 mg of recombinant tPA (r-tPA) into each lung, followed by 5 mg of r-tPA over 5 hours; the total dose was 7 mg of r-tPA for patients with unilateral PEs and 14 mg for those with bilateral PEs, the researchers said. The median times for catheter placement and total procedure were 15 minutes and 54 minutes, respectively.
The number of segmental PA branches with total or subtotal occlusions decreased significantly, from 40.5% at baseline to 11.7% at 48 hours, and proximal PA branch total or subtotal occlusions decreased significantly, from 28.7% at baseline to 11.0% at 48 hours (P < 0.0001 for both).
The magnitude of the reductions in both total and subtotal occlusions of segmental arteries was significantly correlated with the extent of right ventricle recovery (measured by the reduction in right ventricular/left ventricular ratio) with a correlation coefficient of 0.287 (P = .0026); however, this correlation was not observed in the proximal PA arteries (correlation coefficient 0.132, P =.173).
One major bleeding event occurred within 72 hours in a patient who also experienced a device-related left common iliac vein thrombosis while not taking anticoagulation medication, and one death unrelated to PE occurred within 30 days.
” The two findings that surprised me include, first, a more than 70% reduction in total and subtotal occlusions in the segmental arteries with such a low dose of r-tPA and, second, the resolution of the blockages was seen not only in the arteries where the device was placed but also at remote sites away from the location of the catheter,” Dr. Bashir told this news organization.
The findings were limited by several factors including the lack of long-term clinical follow-up outcomes data and lack of comparison groups who underwent other treatments.
However, “This study implies that we now have a safe therapy for these patients that improves survival and right ventricular recovery in addition to dramatically improving blocked pulmonary arteries,” Dr. Bashir said.
As for additional research,” we need all the current and future prospective pulmonary embolism studies to include an assessment of pulmonary artery blockage resolution as an essential endpoint,” he said.
Catheter Expands Treatment Options
The current study, a subgroup analysis of the RESCUE trial, was one of the first to examine the impact of catheter-directed lysis on distal occlusions, study coauthor Parth M. Rali, MD, said in an interview.
To this point, literature has been limited to evaluation for proximal disease, said Dr. Rali, director of thoracic surgery and medicine and part of the Pulmonary Embolism Response Team at Temple University Hospital, Philadelphia.
Dr. Rali said he was encouraged to see confirmation that the BEC catheter, because of its design, works in patients with proximal or distal occlusive disease.
In clinical practice, “the catheter provides an additional option for care in patients with multiple distal occlusive disease when a systemic tissue plasminogen activator (tPA), may put patient at high bleeding risk,” Dr. Rali said.
Looking ahead, a prospective, observational multicenter study would be useful to validate the findings from the post hoc analysis of the current study, he noted.
The study was sponsored by the National Heart, Lung, and Blood Institute, Commonwealth of Pennsylvania, and Thrombolex Inc., a medical device company developing interventional catheter-based therapies for the rapid and effective treatment of acute venous thromboembolic disorders. Dr. Bashir is a cofounder and has an equity interest in Thrombolex Inc. Dr. Rali disclosed serving as a consultant for Thrombolex, Inari Medical, Viz AI, and ThinkSono.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.