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Friday, October 4, 2019

Safety and Efficacy of Acute Pulmonary Embolism Treated via Large-Bore Aspiration Mechanical Thrombectomy Using the Inari FlowTriever Device

Clinical question
Is it safe and effective to use the Inari FlowTriever Device in treating acute pulmonary embolism?

Take away point
Large-bore aspiration mechanical thrombectomy is safe with a high technical (100%) and clinical success (88%) rates.

Wible, Grant C. et al. Safety and Efficacy of Acute Pulmonary Embolism Treated via Large-Bore Aspiration Mechanical Thrombectomy Using the Inari FlowTriever Device. Journal of Vascular and Interventional Radiology, Volume 30, Issue 9, 1370-75

Click here for abstract

Study design
Single center, retrospective, cohort study of 46 patients between March 2018 – March 2019

One of the authors is a paid consultant for Inari and another receives research support from Inari.

St. Luke’s Hospital and University of Missouri – Kanas City school of medicine, Kansas City, MO, USA.

Figure 2
CT angiogram of a 68-year-old female with saddle pulmonary embolism (a). Right and left pulmonary angiogram demonstrating large filling defects corresponding to patients know PE (b,c). Post aspiration mechanical thrombectomy angiogram demonstrating significant improvement in pulmonary artery flow (d,e). Back table photographs of aspirated clot using the large-bore Inari device (f).


The authors performed a retrospective analysis of the Inari FlowTriever device at their institution when treating massive and intermediate-high risk sub-massive pulmonary embolism. They evaluated the technical success and clinical success of the device in the first year of use at their institution. Technical success involved appropriate device positioning and clinical success was defined by angiographic removal of central clot and change in pulmonary artery pressures before and after clot retrieval. Adverse outcomes were defined by the SIR guidelines of endovascular treatment of PE.

Patients included in this study were referred to IR for massive or intermediate-high risk sub-massive PE. No patients were excluded in the timeframe observed and 2 procedure-related adverse outcomes were reported.

All patients had aspiration mechanical thrombectomy with the Inari FlowTriever device with a 100% technical success rate. Pre and post-aspiration mechanical thrombectomy pressures were obtained, except in 4 cases, where the authors experienced failure of the pressure transducer. A 22F sheath was advanced into the suprarenal IVC via the common femoral vein and the 20F Inari aspiration guide catheter (AGC) was advanced over an 0.035 Amplatz wire into the main or lobar pulmonary artery. Aspiration thrombectomy was performed with the assistance of the self-expanding Nitinol discs to facilitate mechanical clot engagement prior to aspiration. This process was repeated several times in multiple pulmonary arteries until angiographic resolution of central clot was achieved.

There were 2 major procedure-related complications. One with intra-procedural hemoptysis requiring in intubation and another with a hematocrit drop of 15%. Both patients recovered and were discharged from the hospital. 2 patients died in the 30 day post-operative period, which the authors attributed to events prior to the procedure – metastatic pancreatic cancer and severe anoxic brain injury.

There was 100% technical success as defined by the authors. Aspiration related intra-procedure blood loss averaged 280ml with a maximum of 520ml resulting in an average hematocrit drop of 4.6% +/- 2.8% per case. Intra-procedural PA pressure decrease was achieved in 37 patients (88%). Average mean PA pressure improved from 33.9 +/- 8.9 mm Hg before to 27.0 +/- 9 mm Hg after, with a decrease of 6.9 mm Hg (P < 0.0001 and CI 5.0-8.8). All patients survived to hospital discharge.


The authors evaluated the safety and efficacy of the Inari FlowTriever device at their institution over a one-year period. The findings of this study demonstrate the Inari device can be a treatment alternative in patients who are unable to receive systemic or local TPA in the setting of trauma, recent major surgery or other contraindication. This study only looked at a single centers experience with the device, which is useful in evaluating its success in the other interventional radiology departments. Establishing safety is a promising first step in assessing a new treatment paradigm, though comparison with systemic and local lytic and aspiration treatments is still needed.

Post Author
Hasnain Hasham, MD
Interventional Radiology Fellow
Dotter Interventional Institute
Oregon Health and Science University, Portland, OR

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