Purpose Aim of this study was to identify preprocedural parameters, which may predict the application of a complex IVC filter retrieval technique and estimate the procedural outcome by applying two dedicated score systems.Materials and methods In this retrospective multicenter analysis, data concerning patient, filter and procedure characteristics were retrieved from January 2018 to March 2020. Patients were evaluated according to the retrieval technique (standard vs. complex) and the procedural outcome (success vs. failure). Significant differences among these groups were evaluated, and two score systems were developed to predict the application of a complex retrieval technique and the procedural outcome.Results One hundred and sixteen IVC filters were retrieved in 116 patients. In 98 subjects, the filter was retrieved with a standard procedure (Standard group, 84.5% vs. Complex group, 15.5%), while in 106 patients the procedure was successful (Success group, 91.4% vs. Failure group, 8.6%). Statistically significant differences were noted in terms of embedded filter hook, filter apex tilt, angle between filter axis and IVC, caval wall penetration, dwelling time and procedural time. Two score 0–5 points to predict the need for a complex retrieval technique and the procedural outcome were developed, with a prognostic accuracy of 88.8% and 91.4%, respectively.Conclusion Significant differences were appreciable analyzing the sample data comparing both the retrieval technique applied and the procedural outcome. Two predictive scores were developed to assess the need for applying a complex retrieval tech‑nique and to estimate the procedural outcome.Keywords IVC · Filter · Retrieval · Complex technique · Outcome · Scor
Inferior vena cava (IVC) retrievable filters should be removed as soon as possible once patients are no longer at risk of pulmonary embolism, ideally within 8weeks of implantation , even if most of manufacturers ensures retrieval up to 1 year. The recent SIR guidelines  recom‑mend the use of a structured follow‑up program to increase retrieval rates and detect complications in patients who have an IVC filter; interventional radiologists who positioned the filter should track the patient together with the clinician and plan retrieval in a timely manner.Despite the increase in recent years, the filter retrieval rate is still low [3–5], standing at approximately 25% [1, 6] in the USA.Retrieval procedures may be technically challenging requiring the application of complex retrieval techniques , especially in patients with long‑standing filters.Preprocedural clinical and radiological data would certainly help the interventional radiologist to plan the removal procedure and adopt the best suitable endovascular technique.The aim of our multicentric study was to identify demo‑graphic, filter and preprocedural findings, which may predict the application of a complex retrieval technique and estimate the procedural outcome by applying two dedicated score systems.
Materials and methods
This study was approved by the hospital institutional review board of each participating center, and written informed con‑sent was waived due to its retrospective nature.
This is a multicenter analysis where patients from eleven interventional radiology departments were included.In each center, the local radiology information systems and picture archiving systems were reviewed.All patients receiving an IVC filter between January 2018 and December 2019 were identified; then, the analysis was focused on those where the filter was removed up to March 2020.Data about patient, filter and procedure characteristics were retrieved and included into an Excel database file. Demographic data included sex and age. Filter data were brand, dwelling time, angle measured between filter main axis and IVC at removal, caval wall penetration, direction of filter apex and embedded hook. Caval wall penetration was defined as any filter leg overcrossing the IVC wall for more than 3 mm. Embedded hook was considered when the apex of the filter was outside the IVC wall at CT or when no contrast flow between filter apex and caval wall was appre‑ciable at angiography. Procedural characteristics accounted for anticoagulation therapy at the time of retrieval, venous access at positioning and retrieval, beam‑on time, removal outcome, retrieval technique applied and complications (Table1).In accordance with the recent guidelines provided by the SIR , a routine preprocedural imaging was not acquired. When a contrast‑enhanced computed tomography (CT) was performed before the retrieval procedure, this was evaluated; otherwise, filter and procedure characteristics were assessed on angiographic images.
IVC filter placement and retrieval
All procedures were performed by interventional radi‑ologists with more than 5years of experience in vascular diseases.Standard indication for filter positioning was pulmonary embolus or IVC, iliac‑femoro‑popliteal deep vein thrombo‑sis in patients with contraindication, complication or failure to anticoagulation.Indications for retrieval was resolution of deep vein thrombosis and ceased risk of pulmonary embolism.A standard retrieval technique was always applied first, and in case of failure, a complex technique was attempted.A standard retrieval technique was defined as simple snaring of the filter hook followed by over‑sheathing and removal; in most cases, devices are provided by the same manufacturers of the filter implanted; all other additional elements adopted during the procedure identify a complex technical approach (Fig.1).
Data analysis was conducted with a dual approach: first, patients were evaluated according to the retrieval technique and divided into two groups (standard vs. complex); then, data were analyzed according to the procedural outcome and patients were divided into two groups (success vs. failure).Complications were evaluated according to CIRSE clas‑sification system for complications .A comparison between these groups (standard vs. com‑plex; success vs. failure) was performed to identify signifi‑cant variables influencing technique and its success.Finally, two score systems were developed to predict the application of a complex retrieval technique and the proce‑dural outcom
Fig. 1 A 42‑year‑old man, motorbike accident with multiple abdomi‑nal injuries requiring right nephrectomy and coiling embolization because of retroperitoneal bleeding. a Coronal contrast‑enhanced CT reconstruction, venous phase, after nephrectomy: a wide hema‑toma developed into the right renal fossa (white asterisk), compress‑ing the IVC (black dotted arrow) and causing deep vein thrombosis complicated by pulmonary embolism. Coilings artifacts are appreci‑able (black arrows). b Axial CT showing pulmonary embolus into the right pulmonary artery (white circle). c Initial IVC phlebography acquired from right femoral vein confirmed stenosis ab estrinseco of the IVC (black dotted circle) caused by the hematoma (white aster‑isk). Previous coiling is evident too. d Coronal contrast‑enhanced CT reconstruction, delayed phase, acquired after 96 days from filter positioning. Clinical conditions markedly improved and IVC filter retrieval was planned; narrowing of the hematoma (white asterisk) with IVC complete patency and tilting of the filter with embedded hook into the right caval wall are appreciable. e, f After failure of transjugular standard snaring technique, filter was retrieved with a complex approach: through a right femoral access, a balloon was positioned between the caval wall and the filter in order to displace the filter hook that was finally snared through the jugular access and removed without complications. Previous coiling is evident too.