Inferior vena cava (IVC) filters were developed with the goal of offering an alternative for patients with venous thromboembolism and contraindications to anticoagulation. There is much controversy around the indications of IVC filters, and various societal guidelines differ in their recommendations.
Yan Hang Fong
Multiorgan trauma patients are at risk for PE, including fatal PE. Prophylactic IVC filter use has been suggested to prevent PE in these patients, with the intent of reducing mortality. Although this practice may have theoretical merit, data have been limited and risk for IVC filter-related complications may offset any potential benefit of these devices in the absence of appropriate benefit.
Adequately, researchers concluded that early IVC filter placement did not improve patient outcomes. However, several interesting observations should be noted.
Researchers analyzed a prespecified subgroup of patients who survived 7 days, but who did not receive prophylactic anticoagulation within this period due to contraindications (46 in the filter group and 34 in the control group). Although the study was not powered to look at this subgroup, none of the patients in the IVC filter group had symptomatic PE, whereas five (14.7%) in the control group did. Of these, one was a saddle PE diagnosed on postmortem exam. Thus, although widespread use of prophylactic IVC filters in trauma patients is likely wrong, there may be a very specific subpopulation of patients who, if identified beforehand, might benefit from these devices. Unfortunately, identifying such patients, while avoiding overutilization of IVC filters, may prove difficult in clinical practice.
One clue to the nature of these patients was that in the current study, 69% of them had intracranial hematomas or contusions. As a reminder, there is no consensus recommendation from different international societies on the use of prophylactic anticoagulation among patients with intracranial hematomas, likely due to the limited quality of available data.
Also worth mentioning is that in six patients (5% of those who received an IVC filter), retained clots were identified in the IVC filter. This should not immediately denote “dodged PE,” as some of these may have autolysed and one could make the argument that the IVC filter was the cause of these clots. However, perhaps some of these clots signified utility of the device in otherwise sick patients.
Readers should take note of a few additional limitations of the study. First, as the authors recognize, there was an inherent bias introduced regarding decisions on anticoagulation in the filter group. After a filter is placed, the risk for VTE persists, but the contraindication to anticoagulation may have resolved. Therefore, presence of an IVC filter may lead to a delay in starting appropriate anticoagulation.
Second, most patients in both study groups received prophylactic anticoagulation. Although the authors presented an analysis of outcomes among patients who could not receive anticoagulation, these were a relative minority of the whole study. This limits the power of any conclusions about these patients.
Third, timely retrieval (defined as within 90 days), even in the setting of close, dedicated surveillance, was not achieved in 34% of patients. All filters were removed by day 232, except in one patient who became pregnant. Whether this translates to any additional safety concerns was not addressed but has been shown in prior publications. Nonetheless, it reflects the difficulties in daily clinical practice of complying with prompt removal.
Finally, the data cannot be generalized to patients of other ethnicities, especially Asians, for whom thrombotic risk is lower in general, but risk for intracranial bleeding is known to be higher than for Caucasians.
In summary, and in line with most current guidelines, we believe that IVC filters should probably be avoided in most trauma patients. However, we would stop short of stating that they should never be used in this setting. There is likely a subset of trauma patients who can benefit from selective and appropriate IVC filter implantation and retrieval. Hopefully, future studies will better characterize these patients.
Ido Weinberg, MD, and Yan Hang Fong, MBBS
Disclosures: Weinberg and Hang Fong report no relevant financial disclosures.