Pharmacomechanical catheter-directed thrombolysis (PM-CDT) using the Bashir endovascular catheter demonstrated potential for the treatment of intermediate-risk acute pulmonary embolism (PE), findings from the RESCUE* trial have shown.

“[Although] the Bashir endovascular catheter is not yet cleared for the treatment of PE … [the] first-in-human study of PM-CDT with [this] catheter has shown promising early results,” noted Dr Riyaz Bashir from Temple University Hospital, Philadelphia, Pennsylvania, US, at TCT 2022. “[We sought to further] assess the efficacy and safety of a low-dose thrombolytic delivered within the thrombus with a device designed for use in large vessels such as pulmonary arteries (PAs).”

Bashir and colleagues prospectively evaluated 109 individuals (mean age 57 years, 62 percent male) with PE symptom duration of ≤14 days and right ventricular/left ventricular (RV/LV) end diastolic diameter ratio of ≥0.9. About 90 percent of participants had elevated troponin or BNP** levels.

Majority of the participants (94 percent) had bilateral PEs. They received a total of 14 mg of t-PA*** delivered using two devices. For the rest who had unilateral PEs, 7 mg of t-PA was delivered with a single device. All participants received a pulse spray of 2 mg of t-PA into each lung, followed by 5 mg over 5 hours.

At 48 hours, there was a significant reduction in the RV/LV diameter ratio from baseline (mean, from 1.66 to 1.10; p<0.0001), translating to a 33.3-percent reduction. There was also a reduction in PA obstruction from baseline, as reflected by the refined modified Miller index (mean, from 22.42 to 14.35; p<0.0001 [35.9-percent reduction]).

“The magnitude of this reduction is threefold higher than with other [percutaneous mechanical thrombectomy] devices and twofold higher than with other thrombolysis catheters at a similar dose of t-PA,” said Bashir.

The thrombolytic efficiency (ie, percent reduction in PA obstruction) of 1 mg of t-PA was higher with the Bashir endovascular catheter (2.6–2.7 percent) compared with other CDTs (ranging between 0.7 and 1.2 percent). Moreover, the reductions in RV/LV diameter ratio and PA obstruction align with those observed with systemic thrombolysis. [Am J Med Sci 2011;341:33-39; Chest 1994;106:725-726]

The reductions were also associated with improvements in baseline haemodynamic parameters such as cardiac output (mean, from 4.81 to 5.31 L/min; p=0.0029) and systolic PA pressures (mean, from 49.53 to 43.74 mm Hg; p<0.0001) within 5 hours of initiating PM-CDT.

All participants had procedural success. Only one participant had major bleeding (as defined by the International Society of Thrombosis and Haemostasis) within 72 hours, while another had a major device-related adverse event (AE). The major bleeding rate aligns with that seen with anticoagulation alone. [N Engl J Med 2014;370:1402-1411]

The incidences of secondary safety outcomes were also low – with only one incident of clinically relevant non-major bleeding, and seven patients reporting serious AEs.

“The safety profile of the Bashir catheter, [which is a key finding of this study,] and ease of use should facilitate the adoption of this therapy across a wide spectrum of healthcare institutions globally, particularly if [randomized controlled trials] confirm the benefit of PM-CDT in patients with intermediate-risk acute PE,” said Bashir.

“[Taken together,] the RESCUE trial showed that PM-CDT with the Bashir endovascular catheter met its primary efficacy and safety endpoints,” said Bashir. “Future studies are also needed to assess the direct effect of acute reduction in PA obstruction on long-term clinical outcomes, including chronic thromboembolic pulmonary disease/hypertension, post PE syndrome, and long-term mortality.”