April 2016

Endovascular Today published an article in July 2014 in which three doctors well-versed in dealing with inferior vena cava (IVC) filters were interviewed for their opinions on indications, patient follow-up & retrieval rates and the prophylactic use of the devices. The three interviewees were:
•    Dr. William T. Kuo, MD, FSIR, FCCP FCIRSE; Director, Interventional Radiology at Stanford University Medical Center, Stanford, California
•    Dr. Gerard Goh, MD, EBIR; Consultant Interventional & Diagnostic Radiologist at The Alfred Hospital in Melbourne, Australia
•    Dr. Frank Arko, MD; Vascular and Endovascular Surgery at Sanger Heart and Vascular Institute in Charlotte, North Carolina

Guidelines for using IVC Filters
The interviewees were questioned as to what guidelines they and their respective facilities followed re: implanting IVC filters. Their answers point to a problem in the field: namely, that there isn’t one uniform set of guidelines for IVC filter use and that they differ across the board.

Dr. Goh employs his facility’s local guidelines. These are based upon the Cardiovascular and Interventional Radiological Society of Europe’s (CIRSE) “quality improvement guidelines” for IVC filter use. These guidelines essentially indicate IVC use is proper in patients with:
•    Pulmonary embolism (PE), a dangerous condition involving a blood clot that could reach the lungs, potentially causing death
•    Deep-vein thrombosis (DVT), another dangerous condition in which the clots form in the deep veins, typically in the legs
•    History of complications from anticoagulant (blood thinning) therapy or in whom such therapies are either ineffective or contraindicated
•    Severe trauma
•    Poor patient compliance with anticoagulant therapy
•    Free-floating iliofemoral or IVC clots.

Dr. Arko follows different guidelines based upon those of the Society of Interventional Radiology (SIR). His facility only implants IVC filters when there are contraindications to blood thinning therapies or such therapies cause complications or simply don’t work. Dr. Arko’s facility doesn’t use IVC filters in trauma patients, however he knows of prophylactic use in severe trauma cases, such as closed head injuries, spinal cord injuries and long bone or pelvic fractures.

Dr. Kuo and his facility are perhaps the most cautious in their use of IVC filters. He cites various published guidelines, such as those from the American College of Chest Physicians (ACCP), the American Heart Association (AHA), the Eastern Association for the Surgery of Trauma (EAST) and SIR. Dr. Kuo said the most recent and often updated guidelines come from the ACCP. However, the most important factor for Dr. Kuo in deciding to use an IVC filter is based on the PREPIC study.

Follow-up & Removal
IVC filters were not intended to be permanent implants. However, at least in the U.S., there is a huge percentage of patients (66% in 2014) who still have their IVC filters long after the risk of PE has passed. The FDA has issued two safety alerts recommending that IVC filters be removed once the risk of PE has passed.

According to Dr. Kuo, the medical literature as well as the FDA’s MAUDE database for adverse event reporting clearly shows that the longer an IVC filter remains in place after the risk of PE has passed, the greater the risk for serious, potentially fatal, complications. In fact, Dr. Kuo and Stanford developed a follow-up protocol for those patients who only need the temporary type of IVC filter device.

Their patients are automatically scheduled for a return visit for removal “within a few months after successful therapeutic anticoagulation has been achieved and once the risk of PE has diminished.” If the IVC filter is still necessary following that appointment, the clinic closely monitors patients and brings them in for removal once the conditions are met. This is accomplished via the clinic’s in-house FILTER registry.

Dr. Kuo has become the “go-to” surgeon for removal of IVC filters that have been left in too long. He and his team have set up the Stanford IVC Filter Clinic, the purpose of which is to help patients who are not necessarily Stanford Medical Center patients, but who have developed complications with their filters that make standard retrieval almost impossible. The Clinic receives referrals from across the country.

Likewise, Dr. Goh’s facility uses an in-house registry, recording all IVC filter implants and projected dates for removal. A removal appointment is typically set for six weeks post-implant and most of their patients undergo removal surgery at that appointment or a later rescheduled time. The clinic also calls patients who don’t keep their removal appointments and focuses on educating them about the need for prompt removal.

Dr. Arko’s removal protocol has patients return four weeks post-implant for a removal assessment. He said their follow-up is very good “due to the fact that we really do not have any trauma patients in our practice.”

Prophylactic Use of IVC Filters
There is a trend in the U.S. to implant IVC filters in certain patient populations as a prophylactic or preventative measure, even when there is no history of PE or DVT. Such populations typically include those undergoing high-risk surgery like spinal or bariatric procedures. None of the doctors felt that enough evidence existed to support such widespread prophylactic use of the devices.

In fact, Dr. Arko said, “I personally try to limit the use of prophylactic filters.” Dr. Goh is of the opinion that, while such use lowers the occurrence of PE, it increases the risk of DVT and, as such, may not be the best choice.

Dr. Kuo agreed. His practice doesn’t typically implant prophylactic IVC filters in trauma patients without a history of venous thromboembolism (VTE), a condition involving both DVT and PE. He said that most trauma patients don’t get the high level of follow-up necessary to ensure prompt removal, which opens them to greater complications in the future. He currently cooperates with Stanford’s bariatric surgery department if they request the implantation of a prophylactic IVC filter. However, he is considering stopping the practice as data showed “little benefit and perhaps significant risks associated with prophylactic IVC filters among bariatric surgery patients.”

The bottom line is that prolonged use of IVC filters presents the majority of patients with an increased risk of serious, potentially life-threatening complications. There are few, if any, long-term use benefits, especially when compared to these risks, which include:
•    Migration of the IVC filter, including to another blood vessel (called embolization)
•    Fracture of the filter
•    Penetration of the inferior vena cava by the filter
•    IVC perforation of the inferior vena cava
•    IVC thrombosis (a clot forming around the filter)

In an article published in the International Journal of Cardiology in 2014, Drs. Mohamad Alkhouli and Riyaz Bashir question the efficacy of the inferior vena cava (IVC) filter as a device for routine use and raise cautions about the apparent lack of retrieval of these temporary filters, particularly in U.S. patients. There is little doubt that in some cases, the IVC filter is a necessary device; however, the article’s authors expressed concern over “prophylactic” use of IVC filters in certain patient populations.

The IVC filter is a device designed to reduce the possibility of recurrent pulmonary embolism or PE, (blood clots reaching the heart and lungs) as well as fatalities caused by PE. The filters are manufactured by eleven companies and, when called for, are implanted in the inferior vena cava, the largest vein in the human body. The article’s authors state there is “only one randomized-controlled trial” that examined the efficacy of the IVC filter in accomplishing its primary purpose. This study, called PREPIC (Prevention du Risque d’Embolie Pulmonaire par Interruption Cave), showed that, while there was a reduction in PE occurrence, there was no impact on short- or long-term mortality. Worse, PREPIC showed a significant increase in the occurrence of deep-vein thrombosis (DVT). DVT is a condition in which a blood clot (thrombus) forms in one of the deeper veins, typically in the legs. If DVT occurs and the clot breaks loose, PE is a likely result and can be fatal.

Though there is a definite lack of data strongly supporting IVC filter use, Drs. Alkhouli and Bashir found that the use of IVC filters in the U.S. is on the rise. At the time of their writing, IVC filters were being used in 12% – 17% of patients with venous thromboembolism (VTE), a condition involving both DVT and PE, but used in over 40% of patients with a high risk of bleeding. One of the items the doctors found most intriguing was the fact that the implantation rates in patients with a high risk of bleeding was 25 times greater in the U.S. than in Europe. This is likely due to a lack of commonality among guidelines for IVC filter use.

The indications (or conditions calling for use) for IVC filters vary widely, even in the U.S. There are two types of indications: therapeutic and prophylactic. The most common indications are therapeutic and include:

  • DVT or PE and contraindication of anticoagulation therapies (reasons blood thinners should not be used)
  • Anticoagulation therapy failure
  • Massive PE
  • Severe cardiopulmonary (heart and lung) disease complicated by DVT.

Among the more controversial prophylactic uses of IVC filters are:

  • Preventing PE in patients having high-risk surgeries, such as bariatric or spinal procedures
  • Trauma victims without VTE

The problem, according to the authors, is that over half of IVC filter placements fall into the prophylactic category, despite one population-based study of 213 IVC filter patients. That study, conducted by a panel of thrombosis experts, showed that only 51% of those studied actually needed the IVC filter. The other 49% didn’t meet the requisite indications for such therapy. Further, there is a marked lack of agreed-upon definition of “contraindication to anticoagulation” therapy, as well as evidence that several patients who were implanted with an IVC filter due to contraindication to anticoagulation were, in face, on anticoagulation protocols.

One paper, referencing the RIETE registry (registry of patients with venous thromboembolism), stated that 60% of patients studied who were implanted with an IVC filter due to “relative or absolute contraindication to anticoagulation” were on some form of anticoagulant therapy. This further underscores the question of “true contraindications to anticoagulation.”

Perhaps the worst issue with IVC filters is the possibility of serious short- and long-term health complications due to their use. Such complications include:

Migration of the IVC filter, including to another blood vessel (called embolization)

Fracture of the filter

Penetration of the inferior vena cava by the filter

IVC perforation of the inferior vena cava

IVC thrombosis (a clot forming around the filter)

The main reason for these complications is late retrieval of the IVC filters. These devices were not meant to be permanent; rather, they are intended for use only until the risk of PE passes and then they are supposed to be removed. Drs. Alkhouli and Bashir cite research that shows “late filter-related thrombosis” occurred in 8% – 30% of cases studied.

The major problem with IVC filters in the U.S. is the poor rates of retrieval. At the time the authors wrote their article, the highest removal rate reported in the U.S. was 34%, compared to 81% in U.K. They found that some IVC filters aren’t removed for good reasons, such as a tilted filter or a trapped clot.

However, the most common reason they found for lack of removal was poor follow-up by implanting doctors. In the meantime, the IVC filters that remain in the body longer than recommended continue to put patients at risk of very serious health complications. This, even after the FDA issued two safety warnings (2010 & 2014) stating that implanting doctors should remove the IVC filters as soon as the risk of PE has passed.