Outcomes from the ClotTriever Outcomes Registry show symptom duration may underestimate deep vein thrombus chronicity

Rationale and design of the DEFIANCE study: A randomized controlled trial of mechanical thrombectomy versus anticoagulation alone for iliofemoral deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a common medical condition that is associated with clinically significant sequelae, including postthrombotic syndrome (PTS). Anticoagulation alone remains the guideline-recommended treatment for many patients with iliofemoral DVT. Recent technological advances have led to an increase in the use of mechanical thrombectomy for DVT, but mechanical thrombectomy-based procedures have not yet been compared with standard-of-care anticoagulation therapy in randomized studies.

METHODS

The DEFIANCE study (ClinicalTrials.gov: NCT05701917) is an international and actively enrolling randomized controlled trial (RCT) in lower extremity DVT assessing an interventional strategy that includes mechanical thrombectomy with the ClotTriever System (Inari Medical, Irvine, CA) versus anticoagulation alone. Approximately 300 patients with unilateral iliofemoral DVT and symptom duration ≤ 12 weeks will be randomized 1:1. Study conduct includes an independent core laboratory for duplex ultrasound assessment, an independent medical monitor for safety adjudication, and evaluation of PTS severity on the Villalta scale using best clinical practices. The primary endpoint is a composite outcome structured as a hierarchal win ratio of 1) the occurrence of treatment failure or therapy escalation as adjudicated by the medical monitor, with failure defined as amputation or gangrene of the target leg or venous thromboembolism-related mortality, and 2) the assessment of PTS severity at the 6-month follow-up visit. In addition to being a component of the primary endpoint, the severity of PTS at 6 months is also evaluated as a stand-alone secondary endpoint. An additional secondary endpoint is a composite of outcomes at the 10-day visit and is structured as a hierarchal win ratio of 1) vessel compressibility on duplex ultrasound, 2) patient-reported pain, and 3) improvement of edema. The safety endpoints are access site complications requiring endovascular or surgical repair and the occurrence through the 30-day visit of mortality, major bleeding, or new symptomatic pulmonary embolism.

CONCLUSIONS

DEFIANCE will be the first RCT to evaluate a mechanical thrombectomy-based interventional approach versus anticoagulation therapy alone for DVT. The results will inform the treatment of patients with iliofemoral DVT and the prevention of PTS-associated morbidity.

TRIAL REGISTRATION

DEFIANCE: RCT of ClotTriever System Versus Anticoagulation In Deep Vein Thrombosis (DEFIANCE), ClinicalTrials.gov: NCT05701917, URL: https://clinicaltrials.gov/study/NCT05701917?cond=Deep%20Vein%20Thrombosis&term=defiance&rank=1.

Post-Thrombotic Syndrome Morbidity in Mechanical Thrombectomy Versus Pharmacomechanical Catheter-Directed Thrombolysis of Iliofemoral Deep Venous Thrombosis

BACKGROUND

Iliofemoral deep venous thrombosis is strongly associated with post-thrombotic syndrome (PTS). Interventional treatment options include catheter-directed thrombolysis and pharmacomechanical thrombectomy. More recently, there has been a wide dissemination of large-bore devices for mechanical thrombectomy (MT). Both treatment types have been shown to be effective in clinical practice; however, the rates of PTS after MT are poorly characterized.

METHODS

We conducted a retrospective review of patients with acute iliofemoral deep venous thrombosis from 2007 to 2022. Patients were divided into 2 treatment groups: pharmacomechanical catheter-directed thrombolysis (PCDT) and MT with large-bore devices. Our primary endpoint was PTS (Villalta score >4). Secondary outcomes included vessel patency, mortality, and moderate/severe PTS (Villalta score >9). Predictors of PTS were analyzed using multivariable logistic regression.

RESULTS

The median age of our cohort (n = 349) was 49 (interquartile range 35-63) years, 54.2% were female. There were 294 (84.2%) patients treated with PCDT. There were no significant baseline characteristic differences between patients treated with PCDT versus MT aside from increased preoperative anticoagulant use in the MT cohort. The overall rate of PTS was 19.1%. There were no differences in rates of PTS, moderate-severe PTS, stent patency, mortality between groups, or hospital length of stay. However, patients treated with MT had higher rates of single operating room visit during their admission treatment relative to patients that underwent PCDT (33.3% vs. 9.0%, P < 0.01) and decreased intensive care unit length of stay (2 (1-3) vs. 0.5 (0-2), P < 0.01). MT treatment was not a risk factor for the development of PTS (adjusted odds ratio [aOR] 0.73; [95% confidence interval {CI} 0.30, 1.74]; P = 0.47) or associated with increased Villalta score (β: -0.34; [95% CI-1.28, 0.60]; P = 0.47). Infrainguinal deep venous thrombosis extension (aOR 2.18; [95% CI 1.16, 4.09]; P = 0.02), prior deep venous thrombosis (aOR 2.67; [95% CI 1.38, 5.13]; P < 0.01), and a hypercoagulable state (aOR 2.32; [95% CI 1.19, 4.50]; P = 0.01) were associated with increased risk of PTS.

CONCLUSIONS

Treatment with large-bore MT was not a significant predictor for the development of PTS. MT appears safe, durable, and associated with greater rates of single operating room visit relative to PCDT, which suggests that rapid thrombus removal may be of value.

Early Thrombus Removal for Acute Lower Extremity Deep Vein Thrombosis: Update on Inclusion, Technical Aspects, and Postprocedural Management

Acute lower extremity deep vein thrombosis (DVT) is a common disorder with significant associated morbidity, including pain and swelling, as well as the risk of pulmonary embolism (PE), recurrent venous thromboembolism (VTE) and chronic debilitating post-thrombotic syndrome (PTS). Anticoagulation is standard of care for DVT treatment. It assists in reducing thrombus progression and the occurrence of PE, but incomplete DVT resolution increases the risk of recurrent VTE, valvular insufficiency, and PTS. Endovascular DVT interventions, such as catheter-directed thrombolysis, pharmacomechanical thrombectomy, and large-bore mechanical thrombectomy offer an alternative therapeutic strategy for DVT management. This paper will discuss technical factors and current issues when performing lower extremity DVT interventions including patient selection, anticoagulation, choice of device for endovascular thrombus removal, adjunctive techniques, and venous stent management.Level of Evidence: No level of evidence for: review articles, basic science, laboratory investigations, and experimental study articles.

DETECT-DVT: Detroit Evaluation of Thrombectomy and Evaluation of Intravascular Ultrasound in Deep Vein Thrombosis

Background

We sought to evaluate the use of intravascular ultrasound (IVUS) and mechanical thrombectomy (MT) for the treatment of deep vein thrombosis (DVT) in a community hospital setting.

Methods

Data were analyzed among patients with lower extremity DVT who underwent MT from December 1, 2021 to December 1, 2022.

Results

A total of 1263 patients were evaluated and only 8.8% of patients with DVT received intervention. Of them, 42% were women. The mean age and length of stay were 61.3 years and 3.5 days, respectively. For cases that proceeded to intervention, IVUS was used in 89% of cases, 80% received venoplasty, and 30% received stents. The mean number of MT passes was 4 and the mean contrast volume used was 71 mL. Flow was restored in 96.7% of cases. The procedure was unable to be completed in 1.8% of the cases, and 1.8% had a reported complication after the procedure. Vascular surgery was consulted in 64.4% of the cases, cardiology in 33%, interventional radiology in 12.5%, and 10.9% of the patients had multiple consults. MT was associated with postprocedure reduction of hemoglobin levels (13.4 vs 12.1; P < .001) and no change in postprocedure creatinine levels (1.08 vs 1.04; P = .28). IVUS was associated with fewer passes, although this was not statistically significant (P = .09). Additionally, IVUS was associated with increased stenting (P = .03) and venoplasty (P < .001).

Conclusions

MT is shown to be successful in restoring venous flow and is utilized by multiple specialties in the treatment of DVT. Additionally, IVUS was widely used in conjunction with MT, and it was associated with increased advanced interventions, such as venoplasty and stent placement.

Outcomes From Mechanical Thrombectomy for Deep Vein Thrombosis: Insights From the PINC AI Healthcare Database

Background

Mechanical thrombectomy (MT) is playing an increasingly important role in treating deep vein thrombosis (DVT). Although degrees of safety and efficacy have been shown in independent studies, there remains a lack of comparative evidence between MT devices. To address this, we aimed to compare demographics, clinical outcomes, and resource metrics of patients receiving MT for DVT with 3 common devices using a real-world database.

Methods

Patients receiving MT for DVT between January 2018 and March 2022 were identified from the PINC AI Healthcare Database and divided into analysis populations for the AngioJet ZelanteDVT (AJ), the ClotTriever system (CT), and the Indigo system (IN). Rates of in-hospital mortality, resource utilization, and 30-day readmission were compared. Regression modeling was performed to adjust for potential covariates and compare outcomes.

Results

A total of 4455 MT encounters were identified and met inclusion criteria (AJ, 1753; CT, 1344; IN, 1358). In-hospital mortality ranged from 1.0% (CT) to 2.9% (IN), with modeling predicting significantly higher odds for the AJ (odds ratio [OR], 3.42) and IN (OR, 3.38) groups. Similarly, higher rates of resource utilization were predicted in the AJ and IN groups when compared with the reference group (CT). Average costs ranged from $29,549 (CT: SD, $30,705) to $42,705 (IN: SD, $41,114). Thirty-day readmissions ranged from 10.0% (AJ) to 14.6% (IN), while modeling predicted significantly greater odds for the IN group (OR, 1.47).

Conclusions

These results suggest that all MT interventions may be unequal in terms of outcomes and resources, with the CT device associated with lower in-hospital mortality and resource burden.

Intraprocedural Use of the Novel Protrieve Sheath Removes Embolus During Mechanical Thrombectomy of a Complex Iliocaval Deep Vein Thrombosis

Extension of proximal deep vein thrombosis (DVT) into the inferior vena cava (IVC) complicates treatment with mechanical thrombectomy, as the presence of IVC thrombus increases embolization risks. In the case of a 39-year-old man with left-sided iliocaval DVT, the novel Protrieve sheath (Inari Medical, Irvine, California) was intraprocedurally placed in the IVC to ensure such complications would not outweigh the benefits of intervention. During successful thrombectomy, the sheath's wall-apposing funnel trapped and removed procedural embolus from the IVC, with no complications occurring. Studies to determine whether the device can broadly improve the safety of complex DVT procedures are warranted.

Mechanical Thrombectomy vs. Pharmacomechanical Catheter Directed Thrombolysis for the Treatment of Iliofemoral Deep Vein Thrombosis: A Propensity Score Matched Exploratory Analysis of 12 Month Clinical Outcomes

OBJECTIVE

To compare thrombus removal and residual venous symptoms and signs of disease following interventional treatment of iliofemoral deep vein thrombosis (DVT) with mechanical thrombectomy (MT) and pharmacomechanical catheter directed thrombolysis (PCDT).

METHODS

Retrospective cohort analysis of propensity score matched subgroups from the multicentre prospective MT ClotTriever Outcomes registry and the PCDT arm of the randomised Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter Directed Thrombolysis trial. Patients with bilateral DVT, symptom duration greater than four weeks, isolated femoral-popliteal disease, or incomplete case data were excluded. Patients with iliofemoral DVT were propensity score matched (1:1) on 10 baseline covariables, including race, sex, age, body mass index, leg treated, prior thromboembolism, Marder score, symptom duration, provoked deep vein thrombosis status, and Villalta score. Reduction in post-procedure thrombus burden (i.e., Marder scores), assessment of venous symptoms and signs (i.e., Villalta scores) at 12 months, and healthcare resource utilisation were compared between subgroups.

RESULTS

Propensity score matching resulted in 130 patient pairs with no significant differences in baseline characteristics between the MT and PCDT groups. MT was associated with a greater reduction in Marder scores (91.0% vs. 67.7%, p < .001), and a greater proportion of patients at 12 months with no post-thrombotic syndrome (83.1% vs. 63.6%, p = .007) compared with matched patients receiving PCDT. No differences in rates of adjunctive stenting or venoplasty were identified (p = .27). Higher rates of single session treatment were seen with MT (97.7% vs. 26.9%, p < .001), which also showed shorter mean post-procedure hospital stays (1.81 vs. 3.46 overnights, p < .001), and less post-procedure intensive care unit utilisation (2.3% vs. 52.8%, p < .001).

CONCLUSION

Compared with PCDT, MT was associated with greater peri-procedural thrombus reduction, more efficient post-procedure care, and improved symptoms and signs of iliofemoral vein disease at 12 months.

In Vivo Porcine Model of Acute Iliocaval Deep Vein Thrombosis

CLINICAL IMPACT

The study establishes a rapid, technically straightforward, and reproducible porcine large animal model for acute iliocaval deep vein thrombosis (DVT). The procedure can be performed with basic endovascular skillsets. With its procedural efficiency and consistency, the platform is promising for comparative in vivo testing of venous thrombectomy devices in a living host, and for future verification and validation studies to determine efficacy of novel thrombectomy devices relative to predicates.

Single-center experience with the ClotTriever BOLD catheter for deep vein thrombosis percutaneous mechanical thrombectomy of the lower extremity

Background

The ClotTriever System is a percutaneous mechanical thrombectomy system used to treat deep vein thrombosis (DVT). The BOLD catheter is a newer compatible component with a modified coring element for which reported outcomes are limited. This retrospective study aims to assess the preliminary procedural safety and success data for patients treated with the BOLD catheter.

Methods

All consecutive patients with symptomatic lower extremity DVT who underwent thrombectomy with the BOLD catheter between 23 November 2021 and 26 June 2022 at a single center were included. Baseline and procedural characteristics were reported. The primary outcome, intraprocedural safety, was assessed by a chart review of recorded intraprocedural adverse events (AEs) or device malfunction. The secondary outcome, procedural success, was defined as ≥75% reduction in the total occlusion across treated venous segments. This was assessed by an interventionalist review of pre- and postprocedural venograms. Additional outcomes included length of postprocedural hospital stay and assessment of AEs at discharge and a 30-day follow-up visit.

Results

Eleven patient cases were reviewed. The median patient age was 65 years, the majority were women, and all were treated unilaterally. All procedures were completed in a single session without intraprocedural AEs or device malfunction. The median procedural blood loss was 50 ml. A review of pre- and postprocedural venograms showed that 35 venous segments were treated, including the femoral (n = 9), common femoral (n = 9), external iliac (n = 10), and common iliac (n = 7) veins. Procedural success was achieved in 10 patients (90.9%), and the median reduction rate in venous occlusion was 100%. The median length of postprocedural hospital stay was 1 day, and no AEs were noted at discharge (N = 11). One adverse event occurred among the eight patients who completed their follow-up visit. A patient with advanced-stage cancer and medication failure had a recurrent DVT 13 days postprocedure, which was not related to the device or procedure.

Conclusions

No safety concerns concerning the BOLD catheter were raised during the review of the cases included in this analysis, and the device was successful in reducing venous occlusion in patients with symptomatic proximal lower extremity DVT.

Percutaneous mechanical thrombectomy to remove post-thrombotic obstructions and manage post-thrombotic syndrome-associated venous leg ulceration

BACKGROUND

Up to one half of patients with a diagnosis of deep vein thrombosis will develop post-thrombotic syndrome (PTS). Patients with PTS can develop venous leg ulcers (VLUs) due to post-thrombotic obstructions (PTOs) that contribute to prolonged ambulatory venous hypertension. The current treatments for PTS, which include chronic thrombus, synechiae, trabeculations, and inflow lesions, do not target PTOs, and such obstructions can affect stenting success. The aim of the present study was to determine whether removal of chronic PTOs using percutaneous mechanical thrombectomy would promote VLU resolution and positive outcomes.

METHODS

In this retrospective analysis, the characteristics and outcomes for patients with VLUs secondary to chronic PTO who were treated using the ClotTriever System (Inari Medical) between August 2021 and May 2022 were assessed. Technical success was considered the ability to cross a lesion and introduce the thrombectomy device. Clinical success was defined as a decrease of ≥1 in the severity category for the ulcer diameter using the revised venous clinical severity score (score 0, no VLU; score 1, mild VLU [size <2 cm]; score 2, moderate VLU [size 2-6 cm]; score 3, severe VLU [size >6 cm]) at the latest follow-up visit.

RESULTS

A total of 11 patients with 15 VLUs on 14 limbs were identified. Their mean age was 59.7 ± 11.8 years, and four patients (36.4%) were women. The median VLU duration was 11.0 months (interquartile range [IQR], 6.0-17.0 months), and 2 patients had VLUs secondary to a deep vein thrombosis event >40 years previously. All treatments were performed in a single session, with technical success achieved in 100% of the 14 limbs. A median of five passes (IQR, four to six passes) with the ClotTriever catheter were performed per limb. Chronic PTOs were successfully extirpated, and intraprocedural intravascular ultrasound showed effective disruption of venous synechiae and trabeculations. Stents were placed in 10 limbs (71.4%). The time to VLU resolution or the latest follow-up was 12.8 ± 10.5 weeks, and clinical success was achieved for all 15 VLUs (100%), with the revised venous clinical severity score for the ulcer diameter improving from a median of 2 (IQR, 2-2) at baseline to a median score of 0 (IQR, 0-0) at last follow-up. The VLU area had decreased by 96.6% ± 8.7%. Of the 15 VLUs, 12 (80.0%) had resolved completely, and 3 had demonstrated near-complete healing.

CONCLUSIONS

All patients showed complete or near-complete VLU healing within a few months after mechanical thrombectomy. Mechanical extirpation and interruption of chronic PTOs allowed for luminal gain and restoration of cephalad inflow. With additional investigation, mechanical thrombectomy with the study device could prove a vital component to the treatment of VLUs secondary to PTOs.

Six-Month Deep Vein Thrombosis Outcomes by Chronicity: Analysis of the Real-World ClotTriever Outcomes Registry

PURPOSE

To analyze the first 250 patients from the prospective, multicenter, industry-sponsored ClotTriever Outcomes (CLOUT) registry, assessing the safety and effectiveness of mechanical thrombectomy for acute, subacute, and chronic deep vein thrombosis (DVT).

MATERIALS AND METHODS

Real-world patients with lower extremity DVT were treated with the ClotTriever System (Inari Medical, Irvine, California). Adjuvant venoplasty, stent placement, or both were performed at the physician's discretion. Thrombus chronicity was determined by visual inspection of removed thrombus, categorizing patients into acute, subacute, and chronic subgroups. Serious adverse events (SAEs) were assessed through 30 days. Clinical and quality-of-life (QoL) outcomes are reported through 6 months.

RESULTS

Thrombus chronicity was designated for 244 of the 250 patients (acute, 32.8%; subacute, 34.8%; chronic, 32.4%) encompassing 254 treated limbs. Complete or near-complete (≥75%) thrombus removal was achieved in 90.8%, 81.9%, and 83.8% of the limbs with acute, subacute, and chronic thrombus, respectively. No fibrinolytics were administered, and 243 (99.6%) procedures were single sessions. One (0.4%) patient in the subacute group experienced a device-related SAE, a fatal pulmonary embolism. On comparing baseline and 6-month data, improvements were demonstrated in median Villalta scores (acute, from 10 to 1; subacute, from 9 to 1; chronic, from 10 to 3; for all, P < .0001) and mean EuroQol group 5-dimension (EQ-5D) self-report questionnaire scores (acute, 0.58 to 0.89; subacute, 0.65 to 0.87; chronic, 0.58 to 0.88; for all, P < .0001). There were no significant differences in outcomes across the subgroups.

CONCLUSIONS

Mechanical thrombectomy using the ClotTriever System with adjunctive venoplasty and stent placement is safe and similarly effective for acute, subacute, and chronic DVT.

Use of the Protrieve Sheath to Trap Embolizing Thrombus During a Complex Mechanical Thrombectomy Procedure With a Thrombosed IVC Filter

Removal of thrombosed inferior vena cava (IVC) filters can be complicated by the risk of thrombus embolization. A 67-year-old patient presented for temporary IVC filter retrieval with complaints of worsening lower extremity swelling. Diagnostic imaging identified significant filter thrombosis and bilateral lower extremity deep vein thrombosis (DVT). In the present case, the novel Protrieve sheath was used to successfully remove the IVC filter and thrombus, with an estimated blood loss of 100 mL. The intraprocedurally generated embolus was trapped and removed without complication. This approach could mitigate embolization risks when removing thrombosed IVC filters or complex DVT.

ClotTriever system for mechanical thrombectomy of deep vein thrombosis

There is increasing evidence that early and comprehensive removal of thrombus in deep vein thrombosis is associated with improved outcomes, including decreased incidence of post-thrombotic syndrome and debilitating long-term symptoms. Catheter-directed thrombolysis is effective for the rapid removal of clot, but it is associated with high bleeding risk. Percutaneous mechanical thrombectomy is a highly effective method for the removal of clot without the use of systemic or catheter-directed thrombolytic therapy. The Inari ClotTriever system (Inari Medical Inc., CA, USA) is a thrombectomy device, which is approved for deep vein thrombosis by the US FDA in 2017. Herein we review the current treatment strategies using the ClotTriever system, its specifications, indications and current state of literature.

Catheter-Directed Interventions for the Treatment of Lower Extremity Deep Vein Thrombosis

Lower extremity deep vein thrombosis (DVT) leads to significant morbidity including pain, swelling, and difficulty walking in the affected limb. If left untreated, DVT increases the risk of pulmonary embolism (PE), recurrent venous thromboembolism (VTE), and post thrombotic syndrome (PTS). The objective of this review was to identify catheter-directed interventions and their success rates for the treatment of lower extremity DVT. A comprehensive search of current and emerging catheter-directed interventions for lower extremity DVT treatment was conducted in PubMed and Google Scholar. Clinical trials, retrospective and prospective observational studies, and case reports were identified to classify percutaneous mechanical thrombectomy (PMT), catheter-directed thrombolysis (CDT), and pharmacomechanical CDT (PCDT) devices based on their mechanism of action and indication of use. Catheter-directed interventions such as PMT, CDT, and PCDT offer an alternative therapeutic strategy for DVT management, particularly in patients with limb-threatening conditions and absolute contraindications to anticoagulants. Currently, there are limited guidelines for the use of mechanical and pharmacomechanical devices because of the lack of clinical evidence available for their use in treatment. Future studies are required to determine the short and long-term effects of using catheter-directed interventions as well as their effectiveness in treating acute versus subacute and chronic DVT.

Restoring venous patency with the ClotTriever following deep vein thrombosis

OBJECTIVE

Though randomized data remains inconclusive, invasive endovenous therapy is increasingly favored in patients with extensive iliocaval or iliofemoral deep venous thrombosis (DVT) to reduce rates of post-thrombotic syndrome (PTS). Previously, pharmacomechanical thrombectomy was the therapy of choice, but the Inari ClotTriever device (Inari Medical, Irvine, California) is an appealing, purely mechanical, alternative. It may reduce bleeding risk, ICU admission, and the need for multiple procedures, when compared to traditional thrombolysis. We present a series of eighteen patients treated with the ClotTriever for extensive iliocaval or iliofemoral DVT.

METHODS

The Inari ClotTriever is a percutaneous mechanical thrombectomy system consisting of an expandable nitinol collection bag that is dragged along the vein wall, separating and capturing thrombus for collection into the retrieval sheath. We retrospectively reviewed all patients undergoing ClotTriever thrombectomy since the device became available at our quaternary referral center in June 2019. Review of these patients' records was determined to be exempt by our institutional IRB.

RESULTS

Eighteen patients underwent ClotTriever thrombectomy between June 2019 and November 2021. The majority of patients (N=16, 89%) presented within 2 weeks of symptom onset, and identifiable provoking factors were present in all patients. The most common provoking factor was anatomy, with May-Thurner Syndrome present in 8 patients. All patients had restoration of unimpeded venous flow in the treated segments, though three had some residual non-flow limiting thrombus. There were no bleeding events or repeat venous procedures. Median post-procedure length of stay of 2 days. Postoperative venous imaging was performed in 15 patients and showed patency of the treated segment in 14 patients. Revised Clinical Venous Severity Scores were available in 14 patients during the course of follow-up. Of these, nine patients' highest scores were 0, two patients' highest scores were 2, two patients' highest scores were 4, and one patient had a high score of 8.

CONCLUSIONS

Venous flow was re-established in all 18 patients treated with the ClotTriever in this series, with no bleeding complications, and median post-procedure length of stay of 2 days. All patients with available follow-up, except 1, retained patency of the treated venous segments and most had mild post-thrombotic syndrome or none at all. These findings suggest that the ClotTriever is a safe and effective way to treat extensive iliocaval/femoral DVT.