- Email: [email protected]
Vena Cava Filter Fracture: Unplanned Obsolescence
196 䡲 Commentary: IVC Filter Fracture—Unplanned Obsolescence
technical expertise in these procedures. A high percentage of patients reported by Dinglasan et al (1) had undergone attempted removal at a previous institution before referral for subsequent removal. In both series, the operators were able to retrieve 100% of the devices. Vijay et al (2) recovered 75% of the fractured filters using the recovery cone as their primary strategy. Dinglasan et al (1) recovered 80% of the filter bodies using endobronchial forceps as their primary strategy. In both articles, ⱖ 20% of the cases required an alternative approach, emphasizing the broad skill set and expertise required for these more complex recoveries. Both sets of operators were able to recover fractured fragments in some patients. Inaccessibility of the fragments precluded removal of some fragments. The potentially dangerous vascular territories in which some fragments came to rest, including the right heart and pulmonary arteries, caused justifiable trepidation in their pursuit. In conclusion, as data continue to mount regarding retrievable filters, these two articles provide valuable guidance to physicians managing these challenging cases. It is apparent that one can expect to see increasing rates of fracture of the Bard recoverable filters as dwell time progresses. Refraining from continued use of a fracture-prone filter with strict adher-
Johnson 䡲 JVIR
ence to indication guidelines is advisable. The authors of both articles seem to establish that recovery of these devices, even after prolonged dwell times with associated fractures, is both feasible and safe in the hands of highly skilled operators. When the physician is faced with a patient who previously received such a device, strong consideration needs to be given to retrieving the device and, if clinically warranted, replacing it with a proven durable alternative.
REFERENCES 1. Dinglasan LAV, Trerotola SO, Shlansky-Goldberg RD, Mondschein J, Stavropoulos SW. Removal of fractured inferior vena cava filters: feasibility and outcomes. J Vasc Interv Radiol 2012; 23:181–187. 2. Vijay K, Huges JA, Burdette AS, et al. Fractured Bard Recovery, G2, and G2 express inferior vena cava filters: incidence, clinical consequences, and outcomes of removal attempt. J Vasc Interv Radiol 2012; 23:188 –194. 3. Hull JE, Robertson SW. Bard Recovery filter: evaluation and management of vena cava limb perforation, fracture and migration. J Vasc Interv Radiol 2009; 20:52– 60. 4. Nicholson W, Nicholson WJ, Tolerico P, et al. Prevalence of fracture and fragment embolization of Bard retrievable vena cava filters and clinical implications including cardiac perforation and tamponade. Arch Intern Med 2010; 170:1827–1831.
INVITED COMMENTARY
Vena Cava Filter Fracture: Unplanned Obsolescence Matthew S. Johnson, MD ABBREVIATIONS CTAF ⫽ California Technology Assessment Forum, FDA ⫽ Food and Drug Administration, IVC ⫽ inferior vena cava, PE ⫽ pulmonary embolus, RCT ⫽ randomized controlled trial, VCF ⫽ vena cava filter
The United States Food and Drug Administration (FDA) classifies medical devices into one of three categories, from those posing the least risk to patients, class I, to those posing the highest risk, class III. Unlike class I and II devices, class III devices require an approved premarket approval application before commercial distribution in the
From the Department of Radiology and Imaging Sciences, Indiana University School of Medicine, University Hospital, Room 0290, 550 N. University Blvd., Indianapolis, IN 46202-5253. Final revision received December 6, 2011; accepted December 7, 2011. Address correspondence to M.S.J.; E-mail [email protected] M.S.J. is a paid consultant for Bayer (Robinson Township, Pennsylvania), Boston Scientific (Natick, Massachusetts), Cook (Bloomington, Indiana), CeloNova (Newnan, Georgia), and Nordion (Ottawa, Ontario, Canada), and has research funded by Nordion. © SIR, 2012 J Vasc Interv Radiol 2012; 23:196 –198 DOI: 10.1016/j.jvir.2011.12.004
United States (1). That requirement mandates that a manufacturer demonstrate that the device is safe and effective. Demonstration of safety and efficacy requires performance of a well controlled trial, optimally a randomized controlled trial (RCT). Before 1976, when the FDA gained its current authority to regulate medical devices, vena cava filters (VCFs) were considered class III devices, but filters were reclassified in 2000 as class II devices. As such, VCFs could be cleared for commercial distribution through the less rigorous 510(k) process, which requires only that a manufacturer demonstrate that a device is “substantially equivalent” to a predicate device. It is not surprising, then, given the expense and complexity of RCTs, that no RCT of a VCF to support its commercial distribution has ever been performed. The term “vena cava filter” refers to many different devices, all of which are indicated for the prevention of recurrent pulmonary embolus (PE) when anticoagulation fails or is contraindicated (2). Other than the original Greenfield filter (Boston Scientific, Natick, Massachusetts) and the Bird’s Nest
Volume 23 䡲 Number 2 䡲 February 䡲 2012
filter (Cook, Bloomington, Indiana), which were approved for distribution through the premarket approval process, each of the filters currently available in the US was cleared for distribution by the FDA through the 510(k) pathway, ie, as being substantially equivalent to a predicate device, a legally marketed filter. It is worth noting that the 510(k) process has been used for both nonretrievable VCFs and retrievable VCFs, even though, of course, the Greenfield filter was never approved for retrieval. It is also worth noting that the retrievable VCFs, the first of which was approved in 2003, are all approved for permanent as well as temporary use. Whether it is appropriate that VCFs should be class II devices, that most were cleared through the 510(k) pathway may have contributed to the current lack of understanding of the safety and efficacy of the devices widely used throughout the US today. That lack of understanding, and hence of agreement regarding the safety and efficacy of VCFs, may also account for the relative paucity of their use in the rest of the world. The absence of clinical equipoise should be of great interest to physicians who do place VCFs: Why does the majority of the world use them so infrequently? Are they failing to provide optimal care to their patients? Or are we in the US making inappropriate assumptions? The answers to those questions are not certain: Two articles in the current issue of JVIR, by Dinglasan et al (3) and Vijay et al (4), demonstrate that one of the risks of VCF placement, the risk of filter fracture, and the concomitant clinical risks of that mode of device failure, are real. However, those two reports are representative of the great majority of data on VCFs, in that they are retrospective and uncontrolled. Such studies are of value, in that they may demonstrate patterns, support concepts, and provide procedural detail, but they are incapable of demonstrating safety or efficacy. In addition, although several prospective studies of VCFs have been published (5– 8) in recent years, none involving a specific device has had a control group. The actual safety and efficacy of the available devices are not truly known. Therefore, practice patterns inside and outside the US are necessarily guided by interpretation of incomplete data, leading to wide disagreement in the value of filters in general and in comparative value of specific filters. Indeed, the Cochrane Peripheral Vascular Diseases Group (9) found only two RCTs that fulfilled inclusion criteria in their evaluation of VCFs. In finding no reduction in mortality in either study, they concluded that “no recommendations can be drawn from the two studies” and further that “there is a paucity of VCF outcome evidence when used within currently approved indications and a lack of trials on retrievable filters. Further trials are needed to assess vena caval filter safety and effectiveness” (9). Clearly, “VCF” refers to a very disparate group of devices, differing in their most basic characteristics, including the materials from which they are constructed and their physical characteristics, such as their sizes and shapes. They range from conical devices with or without supporting struts, with or without upper “arms” in addition to lower “legs,” to ovoid devices, to one—the Bird’s Nest filter—with leading and trailing fixation pieces connected by multiple wires. Despite
197
those obvious differences, because we cannot confidently quantify them, it is commonplace to refer to VCFs as if they comprise a homogeneous group, and thus to the “complications of VCFs” or to the “efficacy of VCFs” as a group, rather than to complications of or efficacy of a particular type of filter. The Initial Communication published by the FDA on August 9, 2010 (10), was, then, directed at all retrievable inferior vena cava (IVC) filters. Noting the rapid increase in the numbers of VCFs implanted—projected to be more than 250,000 in 2012—and noting that, since 2005, the FDA had received 921 device adverse event reports, including 56 involving filter fracture, the FDA recommended “that implanting physicians and clinicians responsible for the ongoing care of patients with retrievable IVC filters consider removing the filter as soon as protection from PE is no longer needed” (10). That recommendation, however, failed to account for the differences in materials and design discussed earlier, and the different safety profiles of the various VCFs. Dinglasan et al (3) and Vijay et al (4) describe the authors’ methods and success in removing fractured IVC filters and fragments of those filters. They describe techniques that will likely be of value to physicians treating patients with such devices. Although the techniques do appear to warrant consideration for more widespread use in selected patients, such as those with symptoms attributable to fractured filters, perhaps they are the right answer to the wrong question: Rather than develop aggressive techniques for the removal of fractured filters, it would seem more appropriate to try to prevent that complication and other complications to the greatest extent possible. To that point, it is important to note that the fractured filters removed in both of the studies (3,4) were almost exclusively filters marketed by Bard Peripheral Vascular (Tempe, Arizona): 13 of 15 in the study of Dinglasan et al (3) and all 63 in the study of Vijay et al (4). Both articles (3,4) describe removal of not only Recovery filters but also of G2 filters, and the latter article also describes removal of fractured G2 Express filters. Although fracture is not a complication exclusive to Bard filters (11–14), review of the literature (15–18) suggests that they fracture at a much higher rate than do other filters. Filter fracture is, of course, not the only possible complication of VCF placement. As noted in guidance provided by the FDA (2), myriad other complications can occur during or after VCF placement, paramount among them death, recurrent PE, caval or other thrombosis, filter embolization or migration, and caval penetration. It is likely that the various retrievable and nonretrievable VCFs vary in rates of each concomitant to their use. It is incumbent on the implanting physician to place the “best” VCF possible for his or her patients, even though it is currently not possible to make that determination. That is a sobering thought. What should the considerate physician do? From a strictly scientific standpoint, our practices should be guided by level 1 data. Double-blind, placebocontrolled, multicenter RCTs of each filter should be performed, and the device that yields the greatest protection
198 䡲 Commentary: IVC Filter Fracture—Unplanned Obsolescence
against PE and has the fewest associated complications should be used. Unfortunately, even were it possible to perform an RCT for each filter, it might not be possible to design such a study: Who would comprise the control population? Most US clinicians believe that VCFs are appropriately placed according to their approved indications, ie, in patients with known PE in whom anticoagulation is contraindicated or has failed. It would be difficult for many, including me, to consign such patients to best supportive care. The Prevention du Risque d’Embolie Pulmonaire par Interruption Cave study (19), the major study reviewed by the Cochrane group (9), may have attempted to overcome that ethical concern by performing anticoagulation in every subject in the trial (19). However, that methodology likely contributed to the confounding results of that study: The population comprised people in whom VCFs were not indicated, ie, those who could undergo anticoagulation (19). It is interesting that, even in that population, VCFs led to a statistically significant reduction in PE versus the control group, although, as noted, not to a benefit in overall survival. Even were it possible to overcome ethical considerations, each trial would address only one or perhaps a few clinical scenarios, such as the safety and efficacy of VCF type A in preventing recurrent PE in an adult with malignancy, or of VCF type B in preventing PE in a patient with severe trauma. The complexity of venous thromboembolic disease, coupled with that of VCFs, mitigate against performance of a valuable RCT whose results could be extrapolated to a more protean population. We are left, then, with a difficult scenario. Our practices are necessarily based upon incomplete data. Many, including the majority of physicians outside the United States, question the value of VCF placement. The Cochrane review cannot make a recommendation. The California Technology Assessment Forum (CTAF) recommended, in February 2011, that “the use of IVC filters to protect against pulmonary embolism does not meet CTAF criteria 3, 4, or 5 for safety, effectiveness, and improvement in health outcomes” (20). The US government and insurers pay close attention to the recommendations of bodies such as the Cochrane group and the CTAF. Although many physicians, myself among them, believe that VCF placement is the right thing to do in many patients with venous thromboembolic disease, it is likely that the growing concerns among those with competing opinions will force us to demonstrate the value of that practice. The Society of Interventional Radiology and Society of Vascular Surgery recognize the necessity of the demonstration of the safety and efficacy of the various VCFs now in use in the United States. Representatives of those societies have met several times during the past year with representatives of the FDA and of other societies, including the American College of Chest Physicians, in an attempt to design a study that would address the questions noted here, including the most basic question of all: What is the safety and efficacy of each type of VCF? Those discussions are ongoing. In the meantime, physicians who implant VCFs should try to place the best filter for the particular clinical scenario
Johnson 䡲 JVIR
in which it is being considered, to the extent that the available data allow. Until we understand the relative safety and efficacy of the devices we place, the techniques described by Dinglasan et al (3) and Vijay et al (4) will likely be of value for some time to come.
REFERENCES 1. Pritchard W, Carey R. US Food and Drug Administration and regulation of medical devices in radiology. Radiology 1997; 205:27–36. 2. US Food and Drug Administration. Guidance for Industry and FDA Staff: Guidance for Cardiovascular Intravascular Filter 510(k) Submissions; November 26, 1999. Available at: http://www.fda.gov/Medical Devices/DeviceRegulationandGuidance/GuidanceDocuments/ucm073776. htm. Accessed December 3, 2011. 3. Dinglasan LAV, Trerotola SO, Shlansky-Goldberg RD, Mondschein J, Stavropoulos SW. Removal of fractured inferior vena cava filters: feasibility and outcomes. J Vasc Interv Radiol 2012; 23:181–187. 4. Vijay K, Hughes JA, Burdette AS, et al. Fractured Bard Recovery, G2, and G2 Express inferior vena cava filters: incidence, clinical consequences, and outcomes of removal attempts. J Vasc Interv Radiol 2012; 23:188 –194. 5. Mismetti P, Rivron-Guillot K, Quenet S, et al. A prospective long-term study of 220 patients with a retrievable vena cava filter for secondary prevention of venous thromboembolism. Chest 2007; 131:223–229. 6. Ziegler JW, Dietrich GJ, Cohen SA, Sterling K, Duncan J, Samotowka M. PROOF trial: protection from pulmonary embolism with the OptEase filter. J Vasc Interv Radiol 2008; 19:1165–1170. 7. Binkert CA, Drooz AT, Caridi JG, et al. Technical success and safety of retrieval of the G2 filter in a prospective, multicenter study. J Vasc Interv Radiol 2009; 20:1449 –1453. 8. Johnson MS, Nemcek AA Jr, Benenati JF, et al. The safety and effectiveness of the retrievable option inferior vena cava filter: a United States prospective multicenter clinical study. J Vasc Interv Radiol 2010; 21:1173–1184. 9. Young T, Tang H, Hughes R. Vena caval filters for the prevention of pulmonary embolism. Cochrane Database Syst Rev 2010; 2:CD006212. 10. US Food and Drug Administration. Removing retrievable inferior vena cava filters: initial communication; August 9, 2010. Available at: http:// www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm221676.htm. Accessed December 3, 2011. 11. Maleux G, Heye S, Verhamme P, Vaninbroukx J, Delcroix M. Penetration of a fractured Bird’s Nest filter strut into the liver parenchyma: report of two cases. Acta Radiol; 2011; 52:643– 645. 12. Phelan HA, Gonzalez RP, Scott WC, White CQ, McClure M, Minei JP. Long-term follow-up of trauma patients with permanent prophylactic vena cava filters. J Trauma 2009; 67:485– 489. 13. Sangwaiya MJ, Marentis TC, Walker TG, Stecker M, Wicky ST, Kalva SP. Safety and effectiveness of the Celect inferior vena cava filter: preliminary results. J Vasc Interv Radiol 2009; 20:1188 –1192. 14. Rogers NA, Nguyen L, Minniefield NE, Jessen ME, de Lemos JA. Fracture and embolization of an inferior vena cava filter strut leading to cardiac tamponade. Circulation 2009; 119:2535–2536. 15. Zhu X, Tam MD, Bartholomew J, Newman JS, Sands MJ, Wang W. Retrievability and device-related complications of the G2 filter: a retrospective study of 139 filter retrievals. J Vasc Interv Radiol 2011; 22:806 – 812. 16. Oh JC, Trerotola SO, Dagli M, et al. Removal of retrievable inferior vena cava filters with computed tomography findings indicating tenting or penetration of the inferior vena cava wall. J Vasc Interv Radiol 2011; 22:70 –74. 17. Nicholson W, Nicholson WJ, Tolerico P, et al. Prevalence of fracture and fragment embolization of Bard retrievable vena cava filters and clinical implications including cardiac perforation and tamponade. Arch Intern Med 2010; 170:1827–1831. 18. Hull JE, Robertson SW. Bard Recovery filter: evaluation and management of vena cava limb perforation, fracture, and migration. J Vasc Interv Radiol 2009; 20:52– 60. 19. The PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism. Circulation 2005; 112:416 – 422. 20. Walsh J. Safety and effectiveness of inferior vena cava filters used to protect against pulmonary embolus. San Francisco: California Technology Assessment Forum, 2011. Available at: www.ctaf.org/files/1247_ file_IVC_Filters_final_W.pdf. Accessed December 3, 2011.
technical expertise in these procedures. A high percentage of patients reported by Dinglasan et al (1) had undergone attempted removal at a previous institution before referral for subsequent removal. In both series, the operators were able to retrieve 100% of the devices. Vijay et al (2) recovered 75% of the fractured filters using the recovery cone as their primary strategy. Dinglasan et al (1) recovered 80% of the filter bodies using endobronchial forceps as their primary strategy. In both articles, ⱖ 20% of the cases required an alternative approach, emphasizing the broad skill set and expertise required for these more complex recoveries. Both sets of operators were able to recover fractured fragments in some patients. Inaccessibility of the fragments precluded removal of some fragments. The potentially dangerous vascular territories in which some fragments came to rest, including the right heart and pulmonary arteries, caused justifiable trepidation in their pursuit. In conclusion, as data continue to mount regarding retrievable filters, these two articles provide valuable guidance to physicians managing these challenging cases. It is apparent that one can expect to see increasing rates of fracture of the Bard recoverable filters as dwell time progresses. Refraining from continued use of a fracture-prone filter with strict adher-
Johnson 䡲 JVIR
ence to indication guidelines is advisable. The authors of both articles seem to establish that recovery of these devices, even after prolonged dwell times with associated fractures, is both feasible and safe in the hands of highly skilled operators. When the physician is faced with a patient who previously received such a device, strong consideration needs to be given to retrieving the device and, if clinically warranted, replacing it with a proven durable alternative.
REFERENCES 1. Dinglasan LAV, Trerotola SO, Shlansky-Goldberg RD, Mondschein J, Stavropoulos SW. Removal of fractured inferior vena cava filters: feasibility and outcomes. J Vasc Interv Radiol 2012; 23:181–187. 2. Vijay K, Huges JA, Burdette AS, et al. Fractured Bard Recovery, G2, and G2 express inferior vena cava filters: incidence, clinical consequences, and outcomes of removal attempt. J Vasc Interv Radiol 2012; 23:188 –194. 3. Hull JE, Robertson SW. Bard Recovery filter: evaluation and management of vena cava limb perforation, fracture and migration. J Vasc Interv Radiol 2009; 20:52– 60. 4. Nicholson W, Nicholson WJ, Tolerico P, et al. Prevalence of fracture and fragment embolization of Bard retrievable vena cava filters and clinical implications including cardiac perforation and tamponade. Arch Intern Med 2010; 170:1827–1831.
INVITED COMMENTARY
Vena Cava Filter Fracture: Unplanned Obsolescence Matthew S. Johnson, MD ABBREVIATIONS CTAF ⫽ California Technology Assessment Forum, FDA ⫽ Food and Drug Administration, IVC ⫽ inferior vena cava, PE ⫽ pulmonary embolus, RCT ⫽ randomized controlled trial, VCF ⫽ vena cava filter
The United States Food and Drug Administration (FDA) classifies medical devices into one of three categories, from those posing the least risk to patients, class I, to those posing the highest risk, class III. Unlike class I and II devices, class III devices require an approved premarket approval application before commercial distribution in the
From the Department of Radiology and Imaging Sciences, Indiana University School of Medicine, University Hospital, Room 0290, 550 N. University Blvd., Indianapolis, IN 46202-5253. Final revision received December 6, 2011; accepted December 7, 2011. Address correspondence to M.S.J.; E-mail [email protected] M.S.J. is a paid consultant for Bayer (Robinson Township, Pennsylvania), Boston Scientific (Natick, Massachusetts), Cook (Bloomington, Indiana), CeloNova (Newnan, Georgia), and Nordion (Ottawa, Ontario, Canada), and has research funded by Nordion. © SIR, 2012 J Vasc Interv Radiol 2012; 23:196 –198 DOI: 10.1016/j.jvir.2011.12.004
United States (1). That requirement mandates that a manufacturer demonstrate that the device is safe and effective. Demonstration of safety and efficacy requires performance of a well controlled trial, optimally a randomized controlled trial (RCT). Before 1976, when the FDA gained its current authority to regulate medical devices, vena cava filters (VCFs) were considered class III devices, but filters were reclassified in 2000 as class II devices. As such, VCFs could be cleared for commercial distribution through the less rigorous 510(k) process, which requires only that a manufacturer demonstrate that a device is “substantially equivalent” to a predicate device. It is not surprising, then, given the expense and complexity of RCTs, that no RCT of a VCF to support its commercial distribution has ever been performed. The term “vena cava filter” refers to many different devices, all of which are indicated for the prevention of recurrent pulmonary embolus (PE) when anticoagulation fails or is contraindicated (2). Other than the original Greenfield filter (Boston Scientific, Natick, Massachusetts) and the Bird’s Nest
Volume 23 䡲 Number 2 䡲 February 䡲 2012
filter (Cook, Bloomington, Indiana), which were approved for distribution through the premarket approval process, each of the filters currently available in the US was cleared for distribution by the FDA through the 510(k) pathway, ie, as being substantially equivalent to a predicate device, a legally marketed filter. It is worth noting that the 510(k) process has been used for both nonretrievable VCFs and retrievable VCFs, even though, of course, the Greenfield filter was never approved for retrieval. It is also worth noting that the retrievable VCFs, the first of which was approved in 2003, are all approved for permanent as well as temporary use. Whether it is appropriate that VCFs should be class II devices, that most were cleared through the 510(k) pathway may have contributed to the current lack of understanding of the safety and efficacy of the devices widely used throughout the US today. That lack of understanding, and hence of agreement regarding the safety and efficacy of VCFs, may also account for the relative paucity of their use in the rest of the world. The absence of clinical equipoise should be of great interest to physicians who do place VCFs: Why does the majority of the world use them so infrequently? Are they failing to provide optimal care to their patients? Or are we in the US making inappropriate assumptions? The answers to those questions are not certain: Two articles in the current issue of JVIR, by Dinglasan et al (3) and Vijay et al (4), demonstrate that one of the risks of VCF placement, the risk of filter fracture, and the concomitant clinical risks of that mode of device failure, are real. However, those two reports are representative of the great majority of data on VCFs, in that they are retrospective and uncontrolled. Such studies are of value, in that they may demonstrate patterns, support concepts, and provide procedural detail, but they are incapable of demonstrating safety or efficacy. In addition, although several prospective studies of VCFs have been published (5– 8) in recent years, none involving a specific device has had a control group. The actual safety and efficacy of the available devices are not truly known. Therefore, practice patterns inside and outside the US are necessarily guided by interpretation of incomplete data, leading to wide disagreement in the value of filters in general and in comparative value of specific filters. Indeed, the Cochrane Peripheral Vascular Diseases Group (9) found only two RCTs that fulfilled inclusion criteria in their evaluation of VCFs. In finding no reduction in mortality in either study, they concluded that “no recommendations can be drawn from the two studies” and further that “there is a paucity of VCF outcome evidence when used within currently approved indications and a lack of trials on retrievable filters. Further trials are needed to assess vena caval filter safety and effectiveness” (9). Clearly, “VCF” refers to a very disparate group of devices, differing in their most basic characteristics, including the materials from which they are constructed and their physical characteristics, such as their sizes and shapes. They range from conical devices with or without supporting struts, with or without upper “arms” in addition to lower “legs,” to ovoid devices, to one—the Bird’s Nest filter—with leading and trailing fixation pieces connected by multiple wires. Despite
197
those obvious differences, because we cannot confidently quantify them, it is commonplace to refer to VCFs as if they comprise a homogeneous group, and thus to the “complications of VCFs” or to the “efficacy of VCFs” as a group, rather than to complications of or efficacy of a particular type of filter. The Initial Communication published by the FDA on August 9, 2010 (10), was, then, directed at all retrievable inferior vena cava (IVC) filters. Noting the rapid increase in the numbers of VCFs implanted—projected to be more than 250,000 in 2012—and noting that, since 2005, the FDA had received 921 device adverse event reports, including 56 involving filter fracture, the FDA recommended “that implanting physicians and clinicians responsible for the ongoing care of patients with retrievable IVC filters consider removing the filter as soon as protection from PE is no longer needed” (10). That recommendation, however, failed to account for the differences in materials and design discussed earlier, and the different safety profiles of the various VCFs. Dinglasan et al (3) and Vijay et al (4) describe the authors’ methods and success in removing fractured IVC filters and fragments of those filters. They describe techniques that will likely be of value to physicians treating patients with such devices. Although the techniques do appear to warrant consideration for more widespread use in selected patients, such as those with symptoms attributable to fractured filters, perhaps they are the right answer to the wrong question: Rather than develop aggressive techniques for the removal of fractured filters, it would seem more appropriate to try to prevent that complication and other complications to the greatest extent possible. To that point, it is important to note that the fractured filters removed in both of the studies (3,4) were almost exclusively filters marketed by Bard Peripheral Vascular (Tempe, Arizona): 13 of 15 in the study of Dinglasan et al (3) and all 63 in the study of Vijay et al (4). Both articles (3,4) describe removal of not only Recovery filters but also of G2 filters, and the latter article also describes removal of fractured G2 Express filters. Although fracture is not a complication exclusive to Bard filters (11–14), review of the literature (15–18) suggests that they fracture at a much higher rate than do other filters. Filter fracture is, of course, not the only possible complication of VCF placement. As noted in guidance provided by the FDA (2), myriad other complications can occur during or after VCF placement, paramount among them death, recurrent PE, caval or other thrombosis, filter embolization or migration, and caval penetration. It is likely that the various retrievable and nonretrievable VCFs vary in rates of each concomitant to their use. It is incumbent on the implanting physician to place the “best” VCF possible for his or her patients, even though it is currently not possible to make that determination. That is a sobering thought. What should the considerate physician do? From a strictly scientific standpoint, our practices should be guided by level 1 data. Double-blind, placebocontrolled, multicenter RCTs of each filter should be performed, and the device that yields the greatest protection
198 䡲 Commentary: IVC Filter Fracture—Unplanned Obsolescence
against PE and has the fewest associated complications should be used. Unfortunately, even were it possible to perform an RCT for each filter, it might not be possible to design such a study: Who would comprise the control population? Most US clinicians believe that VCFs are appropriately placed according to their approved indications, ie, in patients with known PE in whom anticoagulation is contraindicated or has failed. It would be difficult for many, including me, to consign such patients to best supportive care. The Prevention du Risque d’Embolie Pulmonaire par Interruption Cave study (19), the major study reviewed by the Cochrane group (9), may have attempted to overcome that ethical concern by performing anticoagulation in every subject in the trial (19). However, that methodology likely contributed to the confounding results of that study: The population comprised people in whom VCFs were not indicated, ie, those who could undergo anticoagulation (19). It is interesting that, even in that population, VCFs led to a statistically significant reduction in PE versus the control group, although, as noted, not to a benefit in overall survival. Even were it possible to overcome ethical considerations, each trial would address only one or perhaps a few clinical scenarios, such as the safety and efficacy of VCF type A in preventing recurrent PE in an adult with malignancy, or of VCF type B in preventing PE in a patient with severe trauma. The complexity of venous thromboembolic disease, coupled with that of VCFs, mitigate against performance of a valuable RCT whose results could be extrapolated to a more protean population. We are left, then, with a difficult scenario. Our practices are necessarily based upon incomplete data. Many, including the majority of physicians outside the United States, question the value of VCF placement. The Cochrane review cannot make a recommendation. The California Technology Assessment Forum (CTAF) recommended, in February 2011, that “the use of IVC filters to protect against pulmonary embolism does not meet CTAF criteria 3, 4, or 5 for safety, effectiveness, and improvement in health outcomes” (20). The US government and insurers pay close attention to the recommendations of bodies such as the Cochrane group and the CTAF. Although many physicians, myself among them, believe that VCF placement is the right thing to do in many patients with venous thromboembolic disease, it is likely that the growing concerns among those with competing opinions will force us to demonstrate the value of that practice. The Society of Interventional Radiology and Society of Vascular Surgery recognize the necessity of the demonstration of the safety and efficacy of the various VCFs now in use in the United States. Representatives of those societies have met several times during the past year with representatives of the FDA and of other societies, including the American College of Chest Physicians, in an attempt to design a study that would address the questions noted here, including the most basic question of all: What is the safety and efficacy of each type of VCF? Those discussions are ongoing. In the meantime, physicians who implant VCFs should try to place the best filter for the particular clinical scenario
Johnson 䡲 JVIR
in which it is being considered, to the extent that the available data allow. Until we understand the relative safety and efficacy of the devices we place, the techniques described by Dinglasan et al (3) and Vijay et al (4) will likely be of value for some time to come.
REFERENCES 1. Pritchard W, Carey R. US Food and Drug Administration and regulation of medical devices in radiology. Radiology 1997; 205:27–36. 2. US Food and Drug Administration. Guidance for Industry and FDA Staff: Guidance for Cardiovascular Intravascular Filter 510(k) Submissions; November 26, 1999. Available at: http://www.fda.gov/Medical Devices/DeviceRegulationandGuidance/GuidanceDocuments/ucm073776. htm. Accessed December 3, 2011. 3. Dinglasan LAV, Trerotola SO, Shlansky-Goldberg RD, Mondschein J, Stavropoulos SW. Removal of fractured inferior vena cava filters: feasibility and outcomes. J Vasc Interv Radiol 2012; 23:181–187. 4. Vijay K, Hughes JA, Burdette AS, et al. Fractured Bard Recovery, G2, and G2 Express inferior vena cava filters: incidence, clinical consequences, and outcomes of removal attempts. J Vasc Interv Radiol 2012; 23:188 –194. 5. Mismetti P, Rivron-Guillot K, Quenet S, et al. A prospective long-term study of 220 patients with a retrievable vena cava filter for secondary prevention of venous thromboembolism. Chest 2007; 131:223–229. 6. Ziegler JW, Dietrich GJ, Cohen SA, Sterling K, Duncan J, Samotowka M. PROOF trial: protection from pulmonary embolism with the OptEase filter. J Vasc Interv Radiol 2008; 19:1165–1170. 7. Binkert CA, Drooz AT, Caridi JG, et al. Technical success and safety of retrieval of the G2 filter in a prospective, multicenter study. J Vasc Interv Radiol 2009; 20:1449 –1453. 8. Johnson MS, Nemcek AA Jr, Benenati JF, et al. The safety and effectiveness of the retrievable option inferior vena cava filter: a United States prospective multicenter clinical study. J Vasc Interv Radiol 2010; 21:1173–1184. 9. Young T, Tang H, Hughes R. Vena caval filters for the prevention of pulmonary embolism. Cochrane Database Syst Rev 2010; 2:CD006212. 10. US Food and Drug Administration. Removing retrievable inferior vena cava filters: initial communication; August 9, 2010. Available at: http:// www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm221676.htm. Accessed December 3, 2011. 11. Maleux G, Heye S, Verhamme P, Vaninbroukx J, Delcroix M. Penetration of a fractured Bird’s Nest filter strut into the liver parenchyma: report of two cases. Acta Radiol; 2011; 52:643– 645. 12. Phelan HA, Gonzalez RP, Scott WC, White CQ, McClure M, Minei JP. Long-term follow-up of trauma patients with permanent prophylactic vena cava filters. J Trauma 2009; 67:485– 489. 13. Sangwaiya MJ, Marentis TC, Walker TG, Stecker M, Wicky ST, Kalva SP. Safety and effectiveness of the Celect inferior vena cava filter: preliminary results. J Vasc Interv Radiol 2009; 20:1188 –1192. 14. Rogers NA, Nguyen L, Minniefield NE, Jessen ME, de Lemos JA. Fracture and embolization of an inferior vena cava filter strut leading to cardiac tamponade. Circulation 2009; 119:2535–2536. 15. Zhu X, Tam MD, Bartholomew J, Newman JS, Sands MJ, Wang W. Retrievability and device-related complications of the G2 filter: a retrospective study of 139 filter retrievals. J Vasc Interv Radiol 2011; 22:806 – 812. 16. Oh JC, Trerotola SO, Dagli M, et al. Removal of retrievable inferior vena cava filters with computed tomography findings indicating tenting or penetration of the inferior vena cava wall. J Vasc Interv Radiol 2011; 22:70 –74. 17. Nicholson W, Nicholson WJ, Tolerico P, et al. Prevalence of fracture and fragment embolization of Bard retrievable vena cava filters and clinical implications including cardiac perforation and tamponade. Arch Intern Med 2010; 170:1827–1831. 18. Hull JE, Robertson SW. Bard Recovery filter: evaluation and management of vena cava limb perforation, fracture, and migration. J Vasc Interv Radiol 2009; 20:52– 60. 19. The PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism. Circulation 2005; 112:416 – 422. 20. Walsh J. Safety and effectiveness of inferior vena cava filters used to protect against pulmonary embolus. San Francisco: California Technology Assessment Forum, 2011. Available at: www.ctaf.org/files/1247_ file_IVC_Filters_final_W.pdf. Accessed December 3, 2011.