Interim Two-Year Outcomes Following Mechanical Thrombectomy for Deep Vein Thrombosis from the Real-World CLOUT Registry

Objective: Endovascular approaches are increasingly implemented in the treatment of lower
extremity deep vein thrombosis (DVT), despite a lack of long-term data. The CLOUT Registry is a
prospective, all-comer evaluation of DVT patients treated with the ClotTriever System (Inari Medical,
Irvine, CA) with follow-up to 2 years. The objective of this work is to present interim 2-year outcomes for
the first time.

Methods: Patients were enrolled in the CLOUT registry (NCT03575364) irrespective of symptom
duration, failed prior treatment, or bilateral disease. Reported data from 2-year follow-up includes
duplex ultrasound assessment as well as clinical and patient-centered outcomes.

Results: In total, 499 patients (521 treated limbs) were enrolled from 43 clinical sites in the United
States. The median age was 61.9 years, 50.5% (252/499) of patients were female, 23.2% (120/517) had
prior treatment of the current DVT, and 30.7% (124/498) had a contraindication to thrombolytic
therapy. Two-year follow-up data are available for up to 209 patients and are summarized in Table 1. At
2 years, DUS assessment demonstrated present flow in 94.6% (123/130) and normal or partial vein
compressibility in 96.2% (125/130) of treated limbs. The median Villalta score was 9.0 [interquartile
range (IQR): 5.0 – 14.0] at baseline and decreased to 1.0 [IQR: 0.0 – 3.0] at 2 years (p<0.0001).
Furthermore, 81.8% (126/154) were free of post-thrombotic syndrome (PTS, Villalta score <5) and 4.5%
(7/154) had moderate or severe PTS (Villalta score ≥10). The median revised venous clinical severity
score (rVCSS) was 6.0 [IQR: 3.0 – 9.0] at baseline and reduced to 2.0 [IQR: 1.0 – 4.0] at 2 years
(p<0.0001). The median numeric pain rating score (NPRS) was 5.0 [IQR: 2.0 – 8.0] at baseline and
reduced to 0.0 [IQR: 0.0 – 1.0] at 2 years (p<0.0001). The median EuroQol group 5-dimension quality of
life questionnaire (EQ-5D) was 0.687 [IQR: 0.458 – 0.823] at baseline and improved to 1.0 [IQR: 0.861 –
1.0] at 2 years (p<0.0001). The median mid-calf circumference was 39.0 cm [IQR: 35.5 – 42.5] at baseline
and reduced to 37.0 cm [IQR: 33.0 – 40.5] at 2 years (p=0.0023).

Conclusions: This interim analysis of 2-year data from the CLOUT Registry suggests that the ClotTriever
System can provide patients with significant and sustained long-term benefit, such as reduced pain,
improved quality of life, and low rates of chronic complications like PTS.