Thrombus Chronicity Subanalysis of Mechanical Thrombectomy For Deep Vein Thrombosis in Real-World Patients: Six-Month Outcomes from the CLOUT Registry

Abstract

The prospective, multicenter, real-world CLOUT registry assesses the safety and effectiveness of the ClotTriever System (Inari Medical, Irvine, Calif) for the treatment of lower extremity deep venous thrombosis (DVT). The goal of this subanalysis is to evaluate the outcomes of the CLOUT registry based on thrombus chronicity. The CLOUT registry is actively enrolling patients with proximal DVT. Thrombus chronicity was assessed by the treating physician, taking into account patient medical history, intraprocedural imaging, and visual inspection of the extracted thrombus. Patients were classified as having acute (<2 weeks), subacute (2-6 weeks), and/or chronic (>6 weeks) thrombus, using the oldest chronicity extracted per treated limb. The primary effectiveness end point is complete or near-complete (≥75%) thrombus removal as determined by Marder scores adjudicated by an independent core laboratory. Ultrasound and clinical outcomes are reported to 6 months. Of the first 250 patients enrolled in CLOUT, 33% were classified with acute, 35% with subacute, and 32% with chronic thrombus. Median age was 62 years, 52% were male, 23% had prior history of DVT, and 40% were at a high bleeding risk with thrombolytics. All procedures but one were single session (99.6%) with a median of four ClotTriever passes for all chronicity subgroups. No patients required adjunctive thrombolytics. Adjuvant angioplasty was used in 73% (acute: 70%; subacute: 68%; chronic: 84%) and stents in 47% (acute: 46%; subacute: 42%; chronic: 50%) of cases. Median blood loss was 50 mL for all chronicity subgroups. Complete or near-complete thrombus removal was achieved in 85% (acute: 90%; subacute 81%; chronic: 84%) of limbs, including 51% (acute: 54%; subacute: 49%; chronic: 49%) with 100% thrombus removal (Figure ). The post-thrombectomy median hospital stay was 1 day for all chronicity subgroups. At 6 months (Table I), 90% (acute: 88%; subacute: 86%; chronic: 95%) of limbs had flow present and 90% (acute: 86%; subacute: 91%; chronic: 92%) were compressible. Post-thrombotic syndrome was present in 25% (acute: 16%; subacute: 29%; chronic: 29%) of patients and moderate or severe post-thrombotic syndrome in 8% (acute: 2%; subacute: 11%; chronic: 10%) of patients. Outcomes from the real-world CLOUT registry indicate that the ClotTriever System can effectively remove acute, subacute, and chronic thrombus. At six months, significant ultrasound and clinical improvements were observed in all chronicity subgroups. Enrollment to 500 patients and follow-up to 2 years is ongoing (NCT03575364).TableImprovement in ultrasound and clinical outcomes at 6 monthsAcuteSubacuteChronicFlow present888695Compressibility869192PTS rate162929 Moderate or severe PTS rate21110Median decrease in numeric pain rating scale10010090Median decrease in rVCSS715050Median increase in EuroQol group 5-D352235PTS, Post-thrombotic syndrome; rVCSS, Revised Venous Clinical Severity Score.P values are derived from Wilcoxon sign rank or McNemar’s tests. All P values are < .001.Improvements in outcomes at 6 months. Values are percent. Open table in a new tab