- Email: [email protected]
Regarding “Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: A word of caution”
JOURNAL OF VASCULAR SURGERY Volume 48, Number 2
2. MacDonald S. Neuroprotection and flow dynamics in carotid stenting [dissertation]. Sheffield (UK): University of Sheffield Main Library; 2004. Vol I&II [MO115661SH]. 3. Sayeed S, Stanziale SF, Wholey MH, Makaroun MS. Angiographic lesion characteristics can predict adverse outcomes after carotid artery stenting. J Vasc Surg 2008;47:81-7. doi:10.1016/j.jvs.2008.04.064
Regarding “A randomized trial of carotid artery stenting with and without cerebral protection” Barbato and colleagues1 are to be congratulated on performing the first randomized trial comparing carotid artery stenting (CAS) with and without the use of a filter-type cerebral protection device. Although their results do not support the common notion that cerebral protection devices reduce the number of embolic events occurring during CAS, several points of concern arise with respect to the conduct of the trial, patient selection and data analysis. On the basis of a retrospective analysis of non-randomized data with all its inherent limitations, we recently demonstrated that the use of protection devices significantly reduces the incidence of new diffusion-weighted imaging (DWI) lesions after CAS (proportion of patients with any new ipsilateral DWI lesion, 67% in those treated without vs 49% in those treated with protection devices; P ⬍ 0.05) and that approximately 120 to 140 patients would be needed for a randomized trial on the basis of these data.2 As already pointed out by the authors, this trial therefore fell far short of a sample size that would be sufficient to detect a significant difference between both treatment modalities. More importantly, subgroup analyses of our data set have indicated that the beneficial effect of protection devices in preventing the occurrence of new DWI lesions might not pertain to older and asymptomatic patients.3 The negative findings of this trial could thus very well be based on the high number of asymptomatic patients as well as old patients. Along the way it should be noted that a minor or major stroke rate of 13% in asymptomatic patients is unacceptably high, indicating that the majority of patients included in this trial would have been better off with medical treatment alone. In the past few years, evidence has accumulated that certain anatomic features, including a severe vessel tortuosity or aortic arch abnormalities, are associated with an increased periprocedural complication rate during CAS despite the use of cerebral protection devices.4,5 Despite the small patient number, a technical failure rate of 11% in the cerebral protection group stresses the importance of excluding these patients from any future trial. Irrespective of these limitations, we definitely concur with Barbato and colleagues that further randomized trials of unprotected versus protected CAS using DWI as an additional surrogate end point should be expedited. Ideally, these trials should include only patients with a symptomatic carotid stenosis, who are younger than 70 years of age. Andreas Kastrup, MD Sonja Schnaudigel, MD Klaus Gröschel, MD
Letters to the Editor 505
3. Kastrup A, Groschel K, Nagele T, Riecker A, Schmidt F, Schnaudigel S, et al. Effects of age and symptom status on silent ischemic lesions after carotid stenting with and without the use of distal filter devices. AJNR Am J Neuroradiol 2008;29:608-12. 4. Faggioli G, Ferri M, Gargiulo M, Freyrie A, Fratesi F, Manzoli L, et al. Measurement and impact of proximal and distal tortuosity in carotid stenting procedures. J Vasc Surg 2007;46:1119-24. 5. Faggioli GL, Ferri M, Freyrie A, Gargiulo M, Fratesi F, Rossi C, et al. Aortic arch anomalies are associated with increased risk of neurological events in carotid stent procedures. Eur J Vasc Endovasc Surg 2007;33: 436-41. doi:10.1016/j.jvs.2008.03.067
Reply We read with interest the thoughtful letter to the editor of Kastrup et al and agree with most of the voiced comments, in particular the recommendation that additional investigation of the assumed salutory effects of distal protection filters should be undertaken. Our study was significantly underpowered to answer the question in a meaningful manner, and serves only to underscore our lack of understanding of the potential drawbacks of routine filter use during carotid artery stenting (CAS). We are familiar with the authors’ study referred to in the letter, showing findings quite different from ours in the frequency of diffusion-weighted magnetic resonance imaging lesions among patients treated with protected or unprotected CAS. We agree that age and symptomatic status explain many of the differences between the two reports, but the retrospective study methodology, as well as the multitude of filters used with different crossing profiles may have also influenced the findings. For example, their most commonly used filter crosses the lesion as a simple wire, which may be related to a lower incidence of noted microemboli. In addition, the use of filters as well as the performance of magnetic resonance imaging studies in their review did not follow specific indications, introducing a selection bias that further complicates the comparison of our two studies. Although we agree with Kastrup’s comments regarding the lack of benefit of asymptomatic octogenarians from interventional treatment in general and CAS in particular, care must be taken to avoid the use of our clinical outcomes in a very limited dataset to support or refute that contention. A larger review we previously published agrees with the opinions presented in the letter.1 Our current manuscript, however, which includes only a fraction of our total experience, does not shed any additional light on the topic. Michel S. Makaroun, MD University of Pittsburgh Pittsburgh, Pa REFERENCE 1. Stanziale SF, Marone LK, Boules TN, Brimmeier JA, Hill K, Makaroun MS, et al. Carotid artery stenting in octogenarians is associated with increased adverse outcomes. J Vasc Surg 2006;43:297-304. doi:10.1016/j.jvs.2008.04.063
Department of Neurology University of Göttingen Göttingen, Germany REFERENCES
Regarding “Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: A word of caution”
1. Barbato JE, Dillavou E, Horowitz MB, Jovin TG, Kanal E, David S, et al. A randomized trial of carotid artery stenting with and without cerebral protection. J Vasc Surg. In press 2008. 2. Kastrup A, Nagele T, Groschel K, Schmidt F, Vogler E, Schulz J, et al. Incidence of new brain lesions after carotid stenting with and without cerebral protection. Stroke 2006;37:2312-6.
Congratulations to Drs Diehm, Dick, Katzen, Schumidli, Kalka, and Baumgartner for their review article focusing on the phenomenon of neck dilation after endovascular abdominal aortic aneurysm repair.1 However, this review did not include a study we recently conducted and published in the Journal of Endovascular Therapy.2 This study concludes with valuable results because it
JOURNAL OF VASCULAR SURGERY August 2008
506 Letters to the Editor
meets both core requirements of the Society of Vascular Surgery/ International Society of Vascular Surgery, as changes in the aneurysm size were referenced to those measurements obtained from the first set of postoperative images, and the Kaplan-Meier analysis was used to analyze freedom from aortic neck dilatation (AND). The study2 compared 200 patients treated with self-expanding aortic stent-grafts with 42 patients treated with balloon expandable aortic endografts, in terms of AND and endograft migration. The results support several conclusions: First, that endograft migration is correlated to AND; indeed, all 52 patients who presented endograft migration were part of the 58 patients with AND; second, that the ongoing aneurismal degeneration plays a key role in the etiology of AND, as the phenomenon was noticed in both groups (self-expanding and balloon expandable endografts); and third, that the endograft design plays an important role, as the phenomenon of AND was noticed significantly more frequent in the self-expanding group (55 patients in the self-expanding group, versus three patients in the balloon expandable group, P ⫽ .023). In conclusion, this study confirms findings from previous reports3,4 that support that balloon expandable endografts protect from AND.
the study by Dalainas and coworkers2 did neither provide a detailed comparison of clinical and morphological baseline data comparing both treatment groups nor was the statistical analysis adjusted for the above-mentioned factors.2 Therefore, we feel that this series does not substantially strengthen the case for an absence of AND in patients treated with balloon-expandable grafts, and it therefore does not alter our conclusions in this respect. However, we agree it might have been worthwhile to discuss the shortcomings of this study along with the other observational series in our review. In summary, both endovascular and open surgical AAA repair should at present be regarded a “mechanical solution to the problem of progressive expansion of abdominal aortic aneurysm and the risk of rupture.”7 Further studies are required to gain an in-depth understanding of the pathophysiology and potential dedicated mechanisms for its inhibition.
Ilias Dalainas, MD, PhD
Barry T. Katzen, MD
University of Milan Milan, Italy
Baptist Cardiac and Vascular Institute Miami, Fla
REFERENCES
Juerg Schmidli, MD Christoph Kalka, MD Iris Baumgartner, MD
1. Diehm N, Dick F, Katzen BT, Schmidli J, Kalka C, Baumgartner I. Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: a word of caution. J Vasc Surg 2008;47:886-92. 2. Dalainas I, Nano G, Bianchi P, Ramponi F, Casana R, Malacrida G, et al. Aortic neck dilatation and endograft migration are correlated with selfexpanding endografts. J Endovasc Ther 2007;14:318-23. 3. Malas MB, Ohki T, Veith FJ, Chen T, Lipsitz EC, Shah AR, et al. Absence of proximal neck dilatation and graft migration after endovascular aneurysm repair with balloon-expandable stent-based endografts. J Vasc Surg 2005; 42:639-44. 4. Parodi JC, Ferreira LM. Ten-year experience with endovascular therapy in aortic aneurysms. J Am Coll Surg 2002;194:S58-66. doi:10.1016/j.jvs.2008.04.051
Reply We thank Dr Dalainas and colleagues for their interest in our review article on aortic neck dilatation (AND)1 and congratulate them on their recently published paper.2 As elaborated in great detail in our review,1 we are very concerned that the claimed absence of AND in patients treated with balloon-expandable grafts is not sufficiently supported scientifically, but rather based on observational data only. In two series,3,4 the number of patients at risk was reduced to 50% during follow-up, thereby leading to a potential selection bias towards underestimation of AND, especially since one series4 excluded acute and mid-term failures from long-term analysis. Moreover, the authors of that series were not very diligent in describing the methodology used to determine changes in neck dimensions during follow-up.4 These are crucial shortcomings that potentially impair the validity of drawn conclusions. Several studies indicate that AND is an expression of ongoing aneurysmal degeneration in the seemingly non-diseased infrarenal aortic segment.1,5 Thus, why should the presence of an endovascular graft, be it balloon-expandable or self-expandable, alter the natural course of ongoing aneurysmal involvement? Lacking randomized controlled data, this observation is much more likely to be the result of confounding bias. Factors such as large abdominal aortic aneurysm (AAA) neck diameter as well as AAA size and circumferential thrombus were recently shown to independently predict AND.6 Unfortunately,
Nicolas Diehm, MD Florian Dick, MD Swiss Cardiovascular Center Bern, Switzerland
Swiss Cardiovascular Center Bern, Switzerland REFERENCES 1. Diehm N, Dick F, Katzen BT, Schmidli J, Kalka C, Baumgartner I. Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: A word of caution. J Vasc Surg 2008;47:886-92. 2. Dalainas I, Nano G, Bianchi P, Ramponi F, Casana R, Malacrida G, et al. Aortic neck dilatation and endograft migration are correlated with selfexpanding endografts. J Endovasc Ther 2007;14:318-23. 3. Malas MB, Ohki T, Veith FJ, Chen T, Lipsitz EC, Shah AR, et al. Absence of proximal neck dilatation and graft migration after endovascular aneurysm repair with balloon-expandable stent-based endografts. J Vasc Surg 2005;42:639-44. 4. Parodi JC, Ferreira LM. Ten-year experience with endovascular therapy in aortic aneurysms. J Am Coll Surg 2002;194:S58-66. 5. Diehm N, Di Santo S, Schaffner T, Schmidli J, Völzmann J, Jüni P, et al. Severe structural damage, medial neovascularization and upregulation of MMP-9 and p-JNK in infrarenal aortic aneurysm necks. J Vasc Surg; in press 2008. 6. Cao P, Verzini F, Parlani G, Rango PD, Parente B, Giordano G, et al. Predictive factors and clinical consequences of proximal aortic neck dilatation in 230 patients undergoing abdominal aorta aneurysm repair with self-expandable stent-grafts. J Vasc Surg 2003;37:1200-5. 7. Greenhalgh RM, Powell JT. Endovascular repair of abdominal aortic aneurysm. N Engl J Med 2008;358:494-501. doi:10.1016/j.jvs.2008.04.052
Regarding “Incidence and clinical significance of peripheral embolization during percutaneous interventions involving the superficial femoral artery” In the article by Lam et al,1 the authors investigated the incidence and clinical significance of distal embolization during endovascular procedures of the superficial femoral artery. We would like to comment on the study, as well as cite other published studies that were not discussed by the authors.2,3 Amassed litera-
2. MacDonald S. Neuroprotection and flow dynamics in carotid stenting [dissertation]. Sheffield (UK): University of Sheffield Main Library; 2004. Vol I&II [MO115661SH]. 3. Sayeed S, Stanziale SF, Wholey MH, Makaroun MS. Angiographic lesion characteristics can predict adverse outcomes after carotid artery stenting. J Vasc Surg 2008;47:81-7. doi:10.1016/j.jvs.2008.04.064
Regarding “A randomized trial of carotid artery stenting with and without cerebral protection” Barbato and colleagues1 are to be congratulated on performing the first randomized trial comparing carotid artery stenting (CAS) with and without the use of a filter-type cerebral protection device. Although their results do not support the common notion that cerebral protection devices reduce the number of embolic events occurring during CAS, several points of concern arise with respect to the conduct of the trial, patient selection and data analysis. On the basis of a retrospective analysis of non-randomized data with all its inherent limitations, we recently demonstrated that the use of protection devices significantly reduces the incidence of new diffusion-weighted imaging (DWI) lesions after CAS (proportion of patients with any new ipsilateral DWI lesion, 67% in those treated without vs 49% in those treated with protection devices; P ⬍ 0.05) and that approximately 120 to 140 patients would be needed for a randomized trial on the basis of these data.2 As already pointed out by the authors, this trial therefore fell far short of a sample size that would be sufficient to detect a significant difference between both treatment modalities. More importantly, subgroup analyses of our data set have indicated that the beneficial effect of protection devices in preventing the occurrence of new DWI lesions might not pertain to older and asymptomatic patients.3 The negative findings of this trial could thus very well be based on the high number of asymptomatic patients as well as old patients. Along the way it should be noted that a minor or major stroke rate of 13% in asymptomatic patients is unacceptably high, indicating that the majority of patients included in this trial would have been better off with medical treatment alone. In the past few years, evidence has accumulated that certain anatomic features, including a severe vessel tortuosity or aortic arch abnormalities, are associated with an increased periprocedural complication rate during CAS despite the use of cerebral protection devices.4,5 Despite the small patient number, a technical failure rate of 11% in the cerebral protection group stresses the importance of excluding these patients from any future trial. Irrespective of these limitations, we definitely concur with Barbato and colleagues that further randomized trials of unprotected versus protected CAS using DWI as an additional surrogate end point should be expedited. Ideally, these trials should include only patients with a symptomatic carotid stenosis, who are younger than 70 years of age. Andreas Kastrup, MD Sonja Schnaudigel, MD Klaus Gröschel, MD
Letters to the Editor 505
3. Kastrup A, Groschel K, Nagele T, Riecker A, Schmidt F, Schnaudigel S, et al. Effects of age and symptom status on silent ischemic lesions after carotid stenting with and without the use of distal filter devices. AJNR Am J Neuroradiol 2008;29:608-12. 4. Faggioli G, Ferri M, Gargiulo M, Freyrie A, Fratesi F, Manzoli L, et al. Measurement and impact of proximal and distal tortuosity in carotid stenting procedures. J Vasc Surg 2007;46:1119-24. 5. Faggioli GL, Ferri M, Freyrie A, Gargiulo M, Fratesi F, Rossi C, et al. Aortic arch anomalies are associated with increased risk of neurological events in carotid stent procedures. Eur J Vasc Endovasc Surg 2007;33: 436-41. doi:10.1016/j.jvs.2008.03.067
Reply We read with interest the thoughtful letter to the editor of Kastrup et al and agree with most of the voiced comments, in particular the recommendation that additional investigation of the assumed salutory effects of distal protection filters should be undertaken. Our study was significantly underpowered to answer the question in a meaningful manner, and serves only to underscore our lack of understanding of the potential drawbacks of routine filter use during carotid artery stenting (CAS). We are familiar with the authors’ study referred to in the letter, showing findings quite different from ours in the frequency of diffusion-weighted magnetic resonance imaging lesions among patients treated with protected or unprotected CAS. We agree that age and symptomatic status explain many of the differences between the two reports, but the retrospective study methodology, as well as the multitude of filters used with different crossing profiles may have also influenced the findings. For example, their most commonly used filter crosses the lesion as a simple wire, which may be related to a lower incidence of noted microemboli. In addition, the use of filters as well as the performance of magnetic resonance imaging studies in their review did not follow specific indications, introducing a selection bias that further complicates the comparison of our two studies. Although we agree with Kastrup’s comments regarding the lack of benefit of asymptomatic octogenarians from interventional treatment in general and CAS in particular, care must be taken to avoid the use of our clinical outcomes in a very limited dataset to support or refute that contention. A larger review we previously published agrees with the opinions presented in the letter.1 Our current manuscript, however, which includes only a fraction of our total experience, does not shed any additional light on the topic. Michel S. Makaroun, MD University of Pittsburgh Pittsburgh, Pa REFERENCE 1. Stanziale SF, Marone LK, Boules TN, Brimmeier JA, Hill K, Makaroun MS, et al. Carotid artery stenting in octogenarians is associated with increased adverse outcomes. J Vasc Surg 2006;43:297-304. doi:10.1016/j.jvs.2008.04.063
Department of Neurology University of Göttingen Göttingen, Germany REFERENCES
Regarding “Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: A word of caution”
1. Barbato JE, Dillavou E, Horowitz MB, Jovin TG, Kanal E, David S, et al. A randomized trial of carotid artery stenting with and without cerebral protection. J Vasc Surg. In press 2008. 2. Kastrup A, Nagele T, Groschel K, Schmidt F, Vogler E, Schulz J, et al. Incidence of new brain lesions after carotid stenting with and without cerebral protection. Stroke 2006;37:2312-6.
Congratulations to Drs Diehm, Dick, Katzen, Schumidli, Kalka, and Baumgartner for their review article focusing on the phenomenon of neck dilation after endovascular abdominal aortic aneurysm repair.1 However, this review did not include a study we recently conducted and published in the Journal of Endovascular Therapy.2 This study concludes with valuable results because it
JOURNAL OF VASCULAR SURGERY August 2008
506 Letters to the Editor
meets both core requirements of the Society of Vascular Surgery/ International Society of Vascular Surgery, as changes in the aneurysm size were referenced to those measurements obtained from the first set of postoperative images, and the Kaplan-Meier analysis was used to analyze freedom from aortic neck dilatation (AND). The study2 compared 200 patients treated with self-expanding aortic stent-grafts with 42 patients treated with balloon expandable aortic endografts, in terms of AND and endograft migration. The results support several conclusions: First, that endograft migration is correlated to AND; indeed, all 52 patients who presented endograft migration were part of the 58 patients with AND; second, that the ongoing aneurismal degeneration plays a key role in the etiology of AND, as the phenomenon was noticed in both groups (self-expanding and balloon expandable endografts); and third, that the endograft design plays an important role, as the phenomenon of AND was noticed significantly more frequent in the self-expanding group (55 patients in the self-expanding group, versus three patients in the balloon expandable group, P ⫽ .023). In conclusion, this study confirms findings from previous reports3,4 that support that balloon expandable endografts protect from AND.
the study by Dalainas and coworkers2 did neither provide a detailed comparison of clinical and morphological baseline data comparing both treatment groups nor was the statistical analysis adjusted for the above-mentioned factors.2 Therefore, we feel that this series does not substantially strengthen the case for an absence of AND in patients treated with balloon-expandable grafts, and it therefore does not alter our conclusions in this respect. However, we agree it might have been worthwhile to discuss the shortcomings of this study along with the other observational series in our review. In summary, both endovascular and open surgical AAA repair should at present be regarded a “mechanical solution to the problem of progressive expansion of abdominal aortic aneurysm and the risk of rupture.”7 Further studies are required to gain an in-depth understanding of the pathophysiology and potential dedicated mechanisms for its inhibition.
Ilias Dalainas, MD, PhD
Barry T. Katzen, MD
University of Milan Milan, Italy
Baptist Cardiac and Vascular Institute Miami, Fla
REFERENCES
Juerg Schmidli, MD Christoph Kalka, MD Iris Baumgartner, MD
1. Diehm N, Dick F, Katzen BT, Schmidli J, Kalka C, Baumgartner I. Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: a word of caution. J Vasc Surg 2008;47:886-92. 2. Dalainas I, Nano G, Bianchi P, Ramponi F, Casana R, Malacrida G, et al. Aortic neck dilatation and endograft migration are correlated with selfexpanding endografts. J Endovasc Ther 2007;14:318-23. 3. Malas MB, Ohki T, Veith FJ, Chen T, Lipsitz EC, Shah AR, et al. Absence of proximal neck dilatation and graft migration after endovascular aneurysm repair with balloon-expandable stent-based endografts. J Vasc Surg 2005; 42:639-44. 4. Parodi JC, Ferreira LM. Ten-year experience with endovascular therapy in aortic aneurysms. J Am Coll Surg 2002;194:S58-66. doi:10.1016/j.jvs.2008.04.051
Reply We thank Dr Dalainas and colleagues for their interest in our review article on aortic neck dilatation (AND)1 and congratulate them on their recently published paper.2 As elaborated in great detail in our review,1 we are very concerned that the claimed absence of AND in patients treated with balloon-expandable grafts is not sufficiently supported scientifically, but rather based on observational data only. In two series,3,4 the number of patients at risk was reduced to 50% during follow-up, thereby leading to a potential selection bias towards underestimation of AND, especially since one series4 excluded acute and mid-term failures from long-term analysis. Moreover, the authors of that series were not very diligent in describing the methodology used to determine changes in neck dimensions during follow-up.4 These are crucial shortcomings that potentially impair the validity of drawn conclusions. Several studies indicate that AND is an expression of ongoing aneurysmal degeneration in the seemingly non-diseased infrarenal aortic segment.1,5 Thus, why should the presence of an endovascular graft, be it balloon-expandable or self-expandable, alter the natural course of ongoing aneurysmal involvement? Lacking randomized controlled data, this observation is much more likely to be the result of confounding bias. Factors such as large abdominal aortic aneurysm (AAA) neck diameter as well as AAA size and circumferential thrombus were recently shown to independently predict AND.6 Unfortunately,
Nicolas Diehm, MD Florian Dick, MD Swiss Cardiovascular Center Bern, Switzerland
Swiss Cardiovascular Center Bern, Switzerland REFERENCES 1. Diehm N, Dick F, Katzen BT, Schmidli J, Kalka C, Baumgartner I. Aortic neck dilatation after endovascular abdominal aortic aneurysm repair: A word of caution. J Vasc Surg 2008;47:886-92. 2. Dalainas I, Nano G, Bianchi P, Ramponi F, Casana R, Malacrida G, et al. Aortic neck dilatation and endograft migration are correlated with selfexpanding endografts. J Endovasc Ther 2007;14:318-23. 3. Malas MB, Ohki T, Veith FJ, Chen T, Lipsitz EC, Shah AR, et al. Absence of proximal neck dilatation and graft migration after endovascular aneurysm repair with balloon-expandable stent-based endografts. J Vasc Surg 2005;42:639-44. 4. Parodi JC, Ferreira LM. Ten-year experience with endovascular therapy in aortic aneurysms. J Am Coll Surg 2002;194:S58-66. 5. Diehm N, Di Santo S, Schaffner T, Schmidli J, Völzmann J, Jüni P, et al. Severe structural damage, medial neovascularization and upregulation of MMP-9 and p-JNK in infrarenal aortic aneurysm necks. J Vasc Surg; in press 2008. 6. Cao P, Verzini F, Parlani G, Rango PD, Parente B, Giordano G, et al. Predictive factors and clinical consequences of proximal aortic neck dilatation in 230 patients undergoing abdominal aorta aneurysm repair with self-expandable stent-grafts. J Vasc Surg 2003;37:1200-5. 7. Greenhalgh RM, Powell JT. Endovascular repair of abdominal aortic aneurysm. N Engl J Med 2008;358:494-501. doi:10.1016/j.jvs.2008.04.052
Regarding “Incidence and clinical significance of peripheral embolization during percutaneous interventions involving the superficial femoral artery” In the article by Lam et al,1 the authors investigated the incidence and clinical significance of distal embolization during endovascular procedures of the superficial femoral artery. We would like to comment on the study, as well as cite other published studies that were not discussed by the authors.2,3 Amassed litera-