Vena cava filters may fracture frequently

A widely used permanent inferior vena cava filters (IVCF) frequently fractures within two or three years of implantation, a study of 20 patients suggests.

While none of the patients developed life-threatening adverse events due to filter fractures, several reports have previously warned of potentially fatal complications, such as cardiac tamponade or ventricular tachycardia, caused by rupture of the struts, Dr Masaki Sano and colleagues from Japan's Hamamatsu University School of Medicine warn in a research letter published online in the Archives of Internal Medicine.

But the device's manufacturer, Johnson & Johnson, says the fracture rate the researchers found is much higher than the rate identified in larger, longer-term studies. We are in touch with the study authors to ensure that the fractures in their study are included in our safety data base, a J&J spokesperson told Reuters Health via email.

Implanted devices were fractured

While studies found the popular TrapEase IVCF (Cordis Endovascular, Johnson & Johnson) to be safe, effective, and fracture-resistant, Dr Sano and colleagues maintain the studies were performed over a short-term follow-up period, and their evaluation methods seemed to be insufficient to adequately asses IVCF fractures.

Their research letter reports on 20 patients who received the device at their centre between November 2002 and July 2006. (They excluded another six patients who died of malignancy within six months of IVCF implantation.)

On evaluations done at a mean of 50 months after implantation (range, nine to 94 months), three-dimensional computed tomography showed that half of the implanted devices were fractured.

In all cases, fractures involved straight struts. Eight of the devices had a single facture and the remaining two had several. Nine devices appeared to have been fractured by compression of vertebral osteophytes, and three by a tortuous aorta.

Encourage IVCF removals

Based on the findings and other research showing the potential for serious complications of strut fracture, permanent IVCFs should be used with caution and followed closely, Dr Sano and colleagues write.

They note that while the use of retrievable devices with a similar structure to the TrapEase, such as Cordis Endovascular's OptEase, for PTE prophylaxis in trauma patients is dramatically increasing, only about 20% of these devices are actually being removed.

The remaining cases of retrievable IVCF placement are considered permanent IVCF placements owing to technical difficulties during retrieval or loss to follow-up, the researcher’s state. The outcomes of retrievable IVCF placement should be studied and removal should be encouraged.

While filter fractures are a potential complication of vena cava filters, the fracture rates found in this trial are not consistent with our long-term data (which is in a much larger patient population), the J&J spokesperson told Reuters Health, noting that one 751-patient, single-centre study found a 3% fracture rate. We take all product issues very seriously and are working with the authors to better understand their results.

(Reuters Health, December 2011) 



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