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Regarding “Poststent ballooning is associated with increased periprocedural stroke and death rate in carotid artery stenting”
JOURNAL OF VASCULAR SURGERY Volume 62, Number 6
REFERENCES 1. Little RJ, D’Agostino RB, Cohen M, Dickersin K, Emerson SS, Farrar JT, et al. The prevention and treatment of missing data in clinical trials. N Engl J Med 2012;367:1355-60. 2. Little RJ, Rubin DB. Statistical analysis with missing data. 2nd ed. New York: John Wiley & Sons; 2002. 3. Ambler GK, Coughlin PA, Hayes PD, Varty K, Gohel MS, Boyle JR. Incidence and outcomes of severe renal impairment following ruptured abdominal aortic aneurysm repair. [published online ahead of print July 15, 2015]. Eur J Vasc Endovasc Surg. http://dx.doi.org/10.1016/ j.ejvs.2015.06.024. 4. Ambler GK. AAA SCORE. Abdominal aortic aneurysm repair risk calculator. Updated June 26, 2015. Available at: http://www.ambler. me.uk/Vascular/AAARisk/index.shtml. Accessed July 7, 2015. http://dx.doi.org/10.1016/j.jvs.2015.07.039
Regarding “Poststent ballooning is associated with increased periprocedural stroke and death rate in carotid artery stenting” We read with interest this article regarding the risks of balloon angioplasty during carotid stenting procedures. We applaud the authors for recognizing that the goal of carotid stenosis treatment should be stabilization of plaque emboli, not restoration of normal vessel diameter. We would like to point out that there is evidence that carotid stenting can be safely and effectively performed without the use of prestent or poststent ballooning.1,2 As the authors acknowledge, self-expanding stents continue to expand after deployment. Analysis of plaque calcification can determine whether this technique, which we have termed primary carotid stenting (PCS), will achieve satisfactory anatomic results.3 Embolic protection devices are far from benign,4 may fail to catch many emboli generated by balloons,5 and may be unnecessary, thus obviating the need for prestent ballooning in the authors’ protocol. Our preliminary results indicate that PCS may generate fewer microemboli on intraprocedural transcranial Doppler ultrasound and fewer infarcts on postprocedural diffusion-weighted magnetic resonance imaging6 than in standard protocols using balloons. Carotid stenting is emerging as a reasonable alternative to endarterectomy, but the risk of stroke must be lowered. PCS may be the solution. David M. Pelz, MD, FRCPC Department of Medical Imaging Neuroradiology Section University of Western Ontario London Health Sciences Centre University Hospital London, Ontario, Canada Stephen P. Lownie, MD, FRCSC Department of Clinical Neurological Sciences University of Western Ontario London Health Sciences Centre University Hospital London, Ontario, Canada REFERENCES 1. Bussiere M, Pelz DM, Kalapos P, Lee D, Gulka I, Leung A, et al. Results using a self- expanding stent alone in the treatment of severe, symptomatic carotid bifurcation stenosis. J Neurosurg 2008;109:454-60.
Letters to the Editor 1685
2. Lownie SP, Pelz DM, Lee DH, Men S, Gulka I, Kalapos P. Efficacy of treatment of severe carotid bifurcation stenosis by using self-expanding stents without deliberate use of angioplasty balloons. AJNR Am J Neuroradiol 2005;26:1241-8. 3. Pelz DM, Lownie SP, Lee DH, Boulton MR. CTA plaque morphology (the PLAC Scale) on CT angiography: predicting long-term anatomical success of primary carotid stenting. J Neurosurg 2015;27:1-6. 4. Tallarita T, Rabinstein AA, Cloft H, Kallmes D, Oderich GS, Brown RD, et al. Are distal protection devices ‘protective’ during carotid angioplasty and stenting? Stroke 2011;42:1962-6. 5. Almekhlafi MA, Demchuk AM, Mishra S, Bal S, Menon BK, Wiebe S, et al. Malignant emboli on transcranial Doppler during carotid stenting predict postprocedure diffusion-weighted imaging lesions. Stroke 2013;44:1317-22. 6. Lopez-Ojeda P, Muñoz C, Solo K, Boulton M, Lee D, Sharma M, et al. Safety evaluation of primary carotid stenting [Abstract]. Presented at the 52nd Annual Meeting of the American Society of Neuroradiology; Montreal, Quebec, Canada; May 17-22, 2014. http://dx.doi.org/10.1016/j.jvs.2015.06.231
Reply We highly appreciate this thoughtful letter and the discussion it generates. Whereas few studies show no benefit in using protection devices during carotid artery stenting, two systematic reviews in 20031 and 20082 demonstrated that distal protection devices reduce the stroke and death rate by 67% (37 studies, 3200 patients) as well as ipsilateral magnetic resonance imaging lesions by 27% (17 studies, 1400 patients), respectively. In addition, most prospective stent registries and case series found that periprocedural stroke risk is significantly lowered with the use of protection devices. More recently, a meta-analysis showed that flow reversal devices have an even lower microembolic load than distal protection devices.3 The paper quoted in your letter by Tallarita et al4 reports on a composite primary end point of stroke, death, or myocardial infarction. However, closer inspection of individual outcomes shows that the rate of ipsilateral stroke between distal protection and no protection use was 0.8% and 3.8%, respectively; despite no statistical significance because of lack of power, there is an apparent effect that is captured more clearly in the systematic reviews. Whether prestent, poststent, or dual ballooning or lack thereof during carotid artery stenting provides the best “plaque-stabilizing” result is still inconclusive. Some ballooning techniques result in higher hemodynamic depression rates,5 yet others carry benefits in terms of reducing restenosis rates or stroke and death rates.6 The primary stenting studies referenced by the respective authors are relatively small (97 patients in the first and 21 patients in the second) and possibly lend themselves to selection bias. In the paper quoted in your response by Bussiere et al, “preinsertion balloon dilation was only performed if required to enable the stent physically to cross the stenosis,” thereby automatically selecting the most severe of lesions for predilation. The notion to minimize manipulation at the carotid lesion has substantial merit. However, forgoing protection devices and any ballooning may prove detrimental. The majority of our patients have severe stenotic lesions, in which forcing a 5F stent delivery system without embolic protection is conceivably worse than passing a balloon or an embolic protection device with a much smaller diameter. In addition, it is perhaps valid to argue that protected predilation provides a degree of “contouring” of the carotid artery under safer conditions than allowing aggressive self-expansion of the stent. Primary stenting may prove useful in moderately stenotic noncalcified lesions. However, we are of the opinion that best medical management might be the better option in these patients. Despite our aforementioned points of view, we reserve final judgment on experimental techniques such as primary carotid
REFERENCES 1. Little RJ, D’Agostino RB, Cohen M, Dickersin K, Emerson SS, Farrar JT, et al. The prevention and treatment of missing data in clinical trials. N Engl J Med 2012;367:1355-60. 2. Little RJ, Rubin DB. Statistical analysis with missing data. 2nd ed. New York: John Wiley & Sons; 2002. 3. Ambler GK, Coughlin PA, Hayes PD, Varty K, Gohel MS, Boyle JR. Incidence and outcomes of severe renal impairment following ruptured abdominal aortic aneurysm repair. [published online ahead of print July 15, 2015]. Eur J Vasc Endovasc Surg. http://dx.doi.org/10.1016/ j.ejvs.2015.06.024. 4. Ambler GK. AAA SCORE. Abdominal aortic aneurysm repair risk calculator. Updated June 26, 2015. Available at: http://www.ambler. me.uk/Vascular/AAARisk/index.shtml. Accessed July 7, 2015. http://dx.doi.org/10.1016/j.jvs.2015.07.039
Regarding “Poststent ballooning is associated with increased periprocedural stroke and death rate in carotid artery stenting” We read with interest this article regarding the risks of balloon angioplasty during carotid stenting procedures. We applaud the authors for recognizing that the goal of carotid stenosis treatment should be stabilization of plaque emboli, not restoration of normal vessel diameter. We would like to point out that there is evidence that carotid stenting can be safely and effectively performed without the use of prestent or poststent ballooning.1,2 As the authors acknowledge, self-expanding stents continue to expand after deployment. Analysis of plaque calcification can determine whether this technique, which we have termed primary carotid stenting (PCS), will achieve satisfactory anatomic results.3 Embolic protection devices are far from benign,4 may fail to catch many emboli generated by balloons,5 and may be unnecessary, thus obviating the need for prestent ballooning in the authors’ protocol. Our preliminary results indicate that PCS may generate fewer microemboli on intraprocedural transcranial Doppler ultrasound and fewer infarcts on postprocedural diffusion-weighted magnetic resonance imaging6 than in standard protocols using balloons. Carotid stenting is emerging as a reasonable alternative to endarterectomy, but the risk of stroke must be lowered. PCS may be the solution. David M. Pelz, MD, FRCPC Department of Medical Imaging Neuroradiology Section University of Western Ontario London Health Sciences Centre University Hospital London, Ontario, Canada Stephen P. Lownie, MD, FRCSC Department of Clinical Neurological Sciences University of Western Ontario London Health Sciences Centre University Hospital London, Ontario, Canada REFERENCES 1. Bussiere M, Pelz DM, Kalapos P, Lee D, Gulka I, Leung A, et al. Results using a self- expanding stent alone in the treatment of severe, symptomatic carotid bifurcation stenosis. J Neurosurg 2008;109:454-60.
Letters to the Editor 1685
2. Lownie SP, Pelz DM, Lee DH, Men S, Gulka I, Kalapos P. Efficacy of treatment of severe carotid bifurcation stenosis by using self-expanding stents without deliberate use of angioplasty balloons. AJNR Am J Neuroradiol 2005;26:1241-8. 3. Pelz DM, Lownie SP, Lee DH, Boulton MR. CTA plaque morphology (the PLAC Scale) on CT angiography: predicting long-term anatomical success of primary carotid stenting. J Neurosurg 2015;27:1-6. 4. Tallarita T, Rabinstein AA, Cloft H, Kallmes D, Oderich GS, Brown RD, et al. Are distal protection devices ‘protective’ during carotid angioplasty and stenting? Stroke 2011;42:1962-6. 5. Almekhlafi MA, Demchuk AM, Mishra S, Bal S, Menon BK, Wiebe S, et al. Malignant emboli on transcranial Doppler during carotid stenting predict postprocedure diffusion-weighted imaging lesions. Stroke 2013;44:1317-22. 6. Lopez-Ojeda P, Muñoz C, Solo K, Boulton M, Lee D, Sharma M, et al. Safety evaluation of primary carotid stenting [Abstract]. Presented at the 52nd Annual Meeting of the American Society of Neuroradiology; Montreal, Quebec, Canada; May 17-22, 2014. http://dx.doi.org/10.1016/j.jvs.2015.06.231
Reply We highly appreciate this thoughtful letter and the discussion it generates. Whereas few studies show no benefit in using protection devices during carotid artery stenting, two systematic reviews in 20031 and 20082 demonstrated that distal protection devices reduce the stroke and death rate by 67% (37 studies, 3200 patients) as well as ipsilateral magnetic resonance imaging lesions by 27% (17 studies, 1400 patients), respectively. In addition, most prospective stent registries and case series found that periprocedural stroke risk is significantly lowered with the use of protection devices. More recently, a meta-analysis showed that flow reversal devices have an even lower microembolic load than distal protection devices.3 The paper quoted in your letter by Tallarita et al4 reports on a composite primary end point of stroke, death, or myocardial infarction. However, closer inspection of individual outcomes shows that the rate of ipsilateral stroke between distal protection and no protection use was 0.8% and 3.8%, respectively; despite no statistical significance because of lack of power, there is an apparent effect that is captured more clearly in the systematic reviews. Whether prestent, poststent, or dual ballooning or lack thereof during carotid artery stenting provides the best “plaque-stabilizing” result is still inconclusive. Some ballooning techniques result in higher hemodynamic depression rates,5 yet others carry benefits in terms of reducing restenosis rates or stroke and death rates.6 The primary stenting studies referenced by the respective authors are relatively small (97 patients in the first and 21 patients in the second) and possibly lend themselves to selection bias. In the paper quoted in your response by Bussiere et al, “preinsertion balloon dilation was only performed if required to enable the stent physically to cross the stenosis,” thereby automatically selecting the most severe of lesions for predilation. The notion to minimize manipulation at the carotid lesion has substantial merit. However, forgoing protection devices and any ballooning may prove detrimental. The majority of our patients have severe stenotic lesions, in which forcing a 5F stent delivery system without embolic protection is conceivably worse than passing a balloon or an embolic protection device with a much smaller diameter. In addition, it is perhaps valid to argue that protected predilation provides a degree of “contouring” of the carotid artery under safer conditions than allowing aggressive self-expansion of the stent. Primary stenting may prove useful in moderately stenotic noncalcified lesions. However, we are of the opinion that best medical management might be the better option in these patients. Despite our aforementioned points of view, we reserve final judgment on experimental techniques such as primary carotid