Efficacy of IVC filters in Preventing Blood Clots and Pulmonary Embolisms

The efficacy of IVC filters in preventing blood clots and pulmonary embolisms has been a matter of debate in the medical community. Medical studies are conflicted on the issue. The results matter, because thousands of people are relying on implanted IVC filters to prevent these problems, and live with the risks of medical complications that come with an IVC filter. If IVC filters fail to prevent blood clots and pulmonary embolisms, it could mean that their design is defective, which could lead to even more IVC filter lawsuits.

ivc filter

1. Do IVC filters prevent blood clots and pulmonary embolisms?

IVC filters are designed to keep blood clots from traveling up the inferior vena cava vein and to the lungs, where they can block the pulmonary arteries and cause a potentially fatal embolism. However, medical researchers are split over whether they work, or not.

Some studies have found that IVC filters are just as effective as blood thinners at preventing clots and embolisms, making IVC filters an important option for people who cannot take blood thinners. Other studies, though, have come to the opposite conclusion, and warn that IVC filters increase the risk for clotting and do not prevent pulmonary embolisms as often as thought.

2. Several studies show that IVC filters work

On the one hand, there are a handful of studies that suggest that IVC filters are effective at preventing blood clots and pulmonary embolisms.

One study found that, after controlling for the medical histories of IVC filter patients and those who only received blood thinners, the survival rate of both groups was similar.1

Another medical study suggested that patients who received IVC filter implants did not suffer any more short term medical complications if they did not also receive anticoagulants.2

A third study came to a more mixed conclusion, but still supported the use of IVC filters for certain patients. That study found that, when compared to using blood thinners and anticoagulant therapy, IVC filters increased the risk of developing recurrent blood clotting, but lowered the risk of suffering a fatal pulmonary embolism.3

3. Other studies show that IVC filters are ineffective

On the other hand, a few studies have shown that IVC filters are so prone to failure that the risks of having one implanted might outweigh the medical benefits.

In one study, researchers looked at how often IVC filter patients were sent back to the hospital within a year for blood clotting or pulmonary embolism after receiving their filter. The study found that IVC filters did not significantly reduce the odds of a subsequent hospitalization for a pulmonary embolism. In fact, people who had an IVC filter implanted to prevent a pulmonary embolism were even more likely to be sent back to the hospital for blood clots.4

Another study conducted a randomized trial of 400 patients who had deep vein thrombosis – blood clotting problems in deep veins – and who were at risk of a pulmonary embolism. 200 of them received an IVC filter implant and were treated with anticoagulant blood thinner. The other 200 only received the blood thinners. After two years, those who received IVC filter implants only suffered pulmonary embolisms 2.9% less than those who did not receive a filter. However, IVC filter patients were 9.2% more likely to develop recurrent deep vein thrombosis.5

A third study suggested that this increased risk for deep vein thrombosis and blood clotting was actually caused by IVC filters. The study suggested that implanted IVC filters in the inferior vena cava could slow down blood flow there, which could stagnate blood in deeper veins that emptied into it. This stagnation could contribute to the formation of blood clots.6

4. Why an IVC filter's efficacy matters

If the medical community decides that IVC filters are ineffective at preventing pulmonary embolisms and blood clots, it could strengthen the lawsuits that have claimed that IVC filters suffer from a defective design.

The whole point of having an IVC filter implanted in a patient's inferior vena cava vein is to prevent blood clots from migrating through the vein, up the patient's leg to their lungs, and causing a pulmonary embolism. If IVC filters fail to prevent pulmonary embolisms, then it would be a sign that their design is defective.

However, evidence that IVC filters increase the rates of recurrent blood clots is not irrelevant. Pulmonary embolisms are caused by blood clots that migrate to the lungs. By increasing the risk for long term blood clotting, IVC filters can indirectly create a risk for future pulmonary embolisms, effectively backfiring against their primary purpose.


References:

  1. Zektser M, et al., “Effectiveness of Inferior Vena Cava Filters without Anticoagulation Therapy for Prophylaxis of Recurrent Pulmonary Embolism,” Rambam Maimonides Medical Journal 7(3):e0019 (July 28, 2016).

  2. Ortega M, Gahtan V, Roberts A, Matsumoto T, Kerstein M, “Efficacy of anticoagulation post-inferior vena caval filter placement,” The American Surgeon 64(5):419-23 (May 1998).

  3. Muriel A, et al., “Survival Effects of Inferior Vena Cava Filter in Patients With Acute Symptomatic Venous Thromboembolism and a Significant Bleeding Risk,” Journal of the American College of Cardiology 63(16):1675-83 (April 2014).

  4. White RH, Zhou H, Kim J, Romano PS, “A population-based study of the effectiveness of inferior vena cava filter use among patients with venous thromboembolism,” Archives of Internal Medicine 160(13):2033-41 (July 10, 2000).

  5. Decousus H, et al., “A Clinical Trial of Vena Caval Filters in the Prevention of Pulmonary Embolism in Patients with Proximal Deep-Vein Thrombosis,” New England Journal of Medicine 338(7):409-16 (February 12, 1998).

  6. Andreoli JM, Thornburg BG, Hickey RM, “Inferior Vena Cava Filter–Related Thrombus/Deep Vein Thrombosis: Data and Management,” Seminars in Interventional Radiology 33(2):101-4 (June 2016).

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