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03 November 2011

Dendrite and the BSIR publish the First IVC Filter Registry Report

Dendrite Clinical Systems and the British Society of Interventional Radiology have announced the release of the First Inferior Vena Cava Filter Registry Report 2011. The report, published in November 2011, includes analysis of data on 1,255 caval filter placements and 387 attempted retrievals performed at 68 United Kingdom centres between January 2008 and December 2010.


“The registry has accumulated a substantial amount of data. Although there are numerous previous case series reported, there are few prospective studies that enable comparison of different types of filter,” said co-authors of the report, Drs Nicholas Chalmers and Raman Uberoi. “The registry provides information on how operators are using IVC filters, and suggests some possible differences in complications due to the design of filters which may help guide future practice.”


Prior to the Report, there was little information on exactly how many retrievable filters were actually being recovered and on the associated complications with filter placement and filter retrieval. The BSIR instituted the United Kingdom Inferior Vena Cava Filter Registry to try and gain some insight into the use of these devices across the United Kingdom. In particular, the registry assessed the various technical aspects of filter placement; determined the rate of complications during the insertion procedure; examined the frequency of complications whilst the filter is in place; and measured the rate of successful retrieval.


Indications


The data from the Report reveals filter use in the vast majority of patients in the UK follows accepted guidelines and were undertaken for recognised indications according to CIRSE guidelines. The most frequently-recorded indications were: pre-operatively for acute DVT/pulmonary embolus (PE); PE with contra-indications to anticoagulation; and prophylaxis in high risk patients. The most common placement that did not conform to guidelines was DVT associated with malignancy (but without associated PE or surgery). In general, filter complication rates were low, with an average complication rate of 3.5%.


Retrieval


The report states that the chances of a successfully retrieving a filter diminishes with the duration of implantation. For example, filters that have been deployed for more than nine weeks (>62 days) are significantly less likely to be successfully retrieved, compared with those with a shorter duration of implantation (p=0.001). The authors suggest this is likely to be because of incorporation of the device in the caval wall, sometimes due to IVC thrombosis, and penetration of the caval wall by the filter legs.


Mortality


The average in-hospital mortality rate following IVC filter placement is 8.1% indicating that this patient population is overall a high risk group of individuals with most probably a more significant mortality risk from underlying existing conditions. the report states. The large group of patients who have permanent filters inserted appear to have an elevated mortality rate of 12.3% while, as expected, those patients with temporary filters (and most probably only a temporary risk of PE) have a lower mortality rate of 4.3%. The difference in mortality, both in-hospital and at 30 days, between temporary and permanent placements is probably due to difference in severity of the underlying disease.


The initial decision regarding temporary versus permanent filter placement is based on objective clinical criteria, which are reflected in the long-term mortality rates following placement.


PE and DVT


There were 16 reported cases of PE during follow-up and was reported to be the cause of death in six, although this is not supported by objective evidence in most cases. The high mortality in the group where no retrieval was attempted is probably due to deterioration in the patient"s underlying clinical condition. There was no significant difference in mortality between patients who had failed versus successful retrieval.


According to the data reported to this registry, patients were not exposed to a higher risk of future pulmonary embolism than if the filter had been left in situ. The risk of further pulmonary embolism is the same whether or not the filter is retrieved, there were no filter-related deaths reported in the Registry.


Recommendations


In the report, the authors recommend a jugular approach for filter placement should be used when possible, if a right femoral access is not available. They also recommend that if a patient receives a retrievable filter (with the intention to remove), procedures should be put in place to avoid the patient being lost to follow up. They state that filter retrieval appears to be the most successful before nine weeks and patients should be booked for removal within this time-frame.


“The information presented in this report will be invaluable in helping to guide practice in an important area of interventional radiology, with specific recommendations within the report to make filter placement and retrieval easier,” Drs David Kessel (President, BSIR) and Iain Robertson (Vice President, BSIR) write in the forward of the Report.


The IVC filter registry follows on from a series of successful registries such as BIAS (BSIR Iliac Angioplasty & Stenting), ROST (Registry of Oesophageal Stenting), and BDSR (Biliary Drainage & Stenting Registry). The information in these registries helps us to fulfil key objectives of the Society in terms of improving its understanding of contemporary practice.


Although the report is primarily aimed at interventional radiologists who place the filters, it should also be of interest to many other health professionals, especially those who refer patients for IVC filter placement: haematologists, general physicians, general and trauma surgeons. If you would like to purchase the First Inferior Vena Cava Filter Registry Report 2011, please click here.