Plaque Protrusion Detected by Intravascular Ultrasound during Carotid Artery Stenting Norihiko Shinozaki, MD, PhD, Nobuhiko Ogata, MD, PhD, and Yuji Ikari, MD, PhD

Background: Stroke is a major complication of carotid artery stenting (CAS) that can occur during the procedure and for up to 30 days after the procedure in the late phase. Although the cause of late stroke after CAS is unknown, plaque protrusion may be one of the potential causes. This study aims to assess the rate of plaque protrusion during CAS by intravascular ultrasound (IVUS). Methods: We performed 77 consecutive CAS procedures using IVUS between May 2008 and December 2012. The rate of plaque protrusion was assessed at the end of the procedure using IVUS and angiography. Results: Mean age of patients was 72.5 6 7.5 years. Sixtyeight patients were male and 42 had diabetes mellitus. In all, 65 PRECISE stents and 12 Carotid Wall stents were used. All cases were distally protected with filter devices. Six plaque protrusions (7.8%) through the stent struts were detected by IVUS but only 2 (2.6%) by angiography. A predictor of plaque protrusion was preprocedural severe stenosis with flow delay. Additional postdilations (n 5 6) and stent-in-stent implantations (n 5 4) were performed to correct the plaque protrusions. No remaining plaque protrusion was observed in the final IVUS. Overall stroke rate was 2.6% (major 0%, minor 2.6%), and these occurred in the catheterization laboratory, but no late stroke was observed at 30 days after procedure. Conclusions: IVUS can detect plaque protrusion better than angiography. Because adequate management of plaque protrusion may reduce stroke complications, IVUS usage is worth considering. Key Words: Carotid artery stent—plaque protrusion—intravascular ultrasound—complication. Ó 2014 by National Stroke Association

Introduction In earlier reports,1,2 the incidence of complications was reported to be higher after carotid artery stenting (CAS) than after carotid endarterectomy (CEA), and there were no data to suggest an advantage for CAS over CEA. However, the higher rate of complications seen after CAS may have been because of the skill level of the operators or limited use of distal protection device. Recent reports

From the Department of Cardiology, Tokai University School of Medicine, Isehara, Japan. Received March 6, 2014; revision received June 1, 2014; accepted June 8, 2014. Address correspondence to Norihiko Shinozaki, MD, PhD, Department of Cardiology, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa, Japan. E-mail: [email protected]. 1052-3057/$ - see front matter Ó 2014 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2014.06.007

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showed that when CAS was performed by experienced operators with the use of a distal protection device, the outcome was comparable to CEA.3 According to the CREST (Carotid Revascularization Endarterectomy versus Stenting Trial) data,3 the incidence of stroke was higher after CAS than after CEA, whereas cardiac complications were more frequently observed with CEA. To improve the outcome of CAS, it is essential to reduce the incidence of stroke. It has been reported that complications related to stroke develop not only during or immediately after the procedure (ie, the periprocedural period) but also during the postprocedural period from 24 hours to 30 days after the procedure with high frequency.4,5 This suggests that stroke occurring as a complication of CAS cannot be attributed solely to technical problems related to the procedure. It has been suggested that the stroke developing 24 hours or more after CAS is partially associated with

Journal of Stroke and Cerebrovascular Diseases, Vol. 23, No. 10 (November-December), 2014: pp 2622-2625

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thrombosis within the stent. Several case reports endorsing this possibility have been published.6-8 It seems likely that plaque protrusion into the stent is involved in such cases.6-8 According to a previous report based on angiography alone, the frequency of plaque protrusion into the stent after CAS was very low (.4%).9 We previously reported a case with giant plaque protrusions observed by intravascular ultrasound (IVUS).10 Furthermore, the frequency of such protrusions seems to be much higher than previously reported (.4%) based on angiography alone according to our experience with IVUS. Bearing this in mind, we have recently conducted a retrospective analysis of the frequency of plaque protrusions, countermeasures, and prognosis using the data from patients having undergone CAS with the use of IVUS.

Materials and Methods CAS Procedure A total of 77 CAS procedures for 68 patients were performed using IVUS, Volcano S5 Imaging System (Volcano Corporation, San Diego, CA) between May 2008 and December 2012. Patients were prescribed the standard dosage of dual antiplatelet therapy (aspirin 100 mg/day 1 clopidogrel 75 mg/day or ticlopidine 200 mg/day) for all the cases before the procedure for at least 1 week. The CAS procedures were performed under local anesthesia in the endovascular suite by 3 experienced operators. An intra-arterial bolus of heparin was administered to maintain an activated clotting time of more than 250 seconds. Filter-based embolic capture guide wires were mandatory. Initial IVUS imaging was performed after the filter device crossed the lesion, and final IVUS was performed after an optimal angiographic result was obtained. The balloon and stent diameter were determined according to the IVUS findings. If plaque protrusion was detected by IVUS after stenting, balloon dilation was used at first, followed by re-evaluation by IVUS. If plaque protrusion was still remaining, an additional stent was implanted. In these cases, IVUS was repeated at the end of the procedure. Balloon or stent design selection was at the discretion of the operator.

Postprocedure Analysis After the procedure, all patients were prescribed lifelong aspirin (100 mg/day), and prolonged (at least 1 month) clopidogrel 75 mg/day or ticlopidine 200 mg/ day was recommended. Thirty-day clinical follow-ups were performed in outpatient clinics. Medical examinations were performed to diagnose the neurologic or cardiac complication.

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Statistical Analysis Continuous variables are expressed as means 6 standard deviation, whereas discrete variables are given as absolute values, percentages, or both. Continuous variables were compared using Wilcoxon signed rank test. Multiple logistic regression analysis was performed to identify independent predictor of plaque protrusion. All variables with a P value less than .10 in univariate analyses were included in multiple logistic regression analysis. Results were considered statistically significant at P value of .05 or less.

Results Mean age was 72.5 6 7.5 years. Sixty patients were male. Among all patients, 37 had diabetes mellitus, 60 had hypertension, and 55 had dyslipidemia. Fifteen patients were symptomatic, and the other 53 patients were asymptomatic. Sixty-nine cases were performed from the femoral artery, and the other 8 cases were performed via the radial artery. All cases were distally protected with filter devices. In all, 72 lesions were performed with predilatation, and in the other 5 lesions stents were implanted directly without predilatation. Mean diameter of predilatation balloon was 3.8 6 .6 mm. We used 65 PRECISE stents (Cordis, Miami Lakes, FL) and 12 Carotid Wall stents (Boston Scientific, Natick, MA) as the first implanted stents. Mean stent diameter and length were 8.8 6 1.0 mm and 36.9 6 5.8 mm, respectively. Postdilatation was performed for all the lesions. Mean diameter of postdilatation balloon was 5.0 6 .6 mm. Six plaque protrusions (7.8%) were detected by IVUS after postdilatation. Among the 6 plaque protrusions, there were 4 cases where plaque protrusion was not detected by angiography. Table 1 lists the differences between protrusion-positive and protrusion-negative groups. Among the cases with plaque protrusion, 2 were symptomatic, 4 had severe stenosis with delayed flow before the procedure, and the rate of severe stenosis was significantly higher than in those without plaque protrusion (67 % vs. 10 %, P 5 .0031). In multivariate logistic regression analysis, the only independent predictor of plaque protrusion was severe stenosis with delayed flow before the procedure (Table 2). After detecting plaque protrusion, a balloon was used for all the cases at first, and in 4 cases additional stents had to be implanted because plaque protrusion still remained. After performing these procedures, plaque protrusion was corrected, and no stroke occurred in cases with plaque protrusion. The overall stroke rate was 2.6% with temporary symptoms during procedure. No major stroke occurred. There was no stroke after the procedure for 30 days. One patient with aortic valve stenosis died suddenly because of ventricular fibrillation after 6 days.

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Table 1. Comparison of groups with and without plaque protrusion Variables

With protrusion, N 5 6

Without protrusion, N 5 71

P value

Age, mean 6 SD, y Male, n (%) Diabetes mellitus, n (%) Hypertension, n (%) Dyslipidemia, n (%) Symptomatic, n (%) Severe stenosis with delayed filling, n (%) PRECISE stent, n (%) Wall stent, n (%) Predilatation balloon diameter, mean 6 SD, mm Stent diameter, mean 6 SD, mm Stent length, mean 6 SD, mm Postdilatation balloon diameter, mean 6 SD, mm

75.8 6 7.3 5 (83) 5 (83) 6 (100) 4 (67) 2 (33) 4 (67) 5 (83) 1 (17) 3.0 6 1.0 8.7 6 1.0 37.3 6 6.5 4.8 6 0.5

72.4 6 7.6 63 (89) 37 (52) 61 (86) 63 (89) 14 (20) 7 (10) 60 (85) 11 (15) 3.9 6 0.5 8.8 6 1.0 36.9 6 5.8 5.0 6 0.6

.6945 .5384 .2121 ..999 .1718 .5985 .0031 ..999 ..999 .0098 .8048 .7677 .2589

Abbreviation: SD, standard deviation.

Discussion In this study, the incidence of plaque protrusion among patients undergoing CAS with the use of IVUS was 7.8%, much higher than the .4% previously reported based on angiography alone.9 IVUS allows accurate diagnosis of plaque protrusion, and the frequency of plaque protrusion was found to be higher than previously anticipated. The rate of severe stenosis with delayed filling before the procedure in the case with plaque protrusion was significantly higher than in those without plaque protrusion. Severe stenosis with delayed filling was also the only independent predictor of plaque protrusion in multivariate logistic regression analysis. When we perform CAS procedure, we might have to pay more attention to the risk of plaque protrusion for the patient with severe stenosis with delayed filling. During the periprocedural period in patients undergoing CAS, stroke has been reported to develop not only during or immediately after the procedure but also during the period from 24 hours to 30 days postprocedure with high incidence.4 The CASCARD study reported the timing of stroke complication as follows: 46% in the catheter laboratory, 33% within 24 hours, and 21% between 24 hours and 30 days.5 The mechanism of late stroke complication has not been clarified as it cannot Table 2. Multivariate analysis of parameters for the independent prediction of plaque protrusion

Variables

Odds 95% Confidence ratio interval P value

Severe stenosis with 17.58 delayed filling Predilatation balloon .68 diameter

2.65-116.73

.0030

.33-1.45

.3252

be explained by distal protection techniques used during the procedure. It was reported that thrombus formation and onset of stroke were seen in some patients after plaque protrusion for several days after the procedure.6-8 Thus, we hypothesized the plaque protrusion may be one of the causes for late stroke. After plaque protrusion was detected, all patients underwent balloon dilatation, resulting in disappearance of the plaque in 2 cases (33%). Balloon dilatation probably fixed the prolapsing plaque by compression or it caused the plaque to be dislocated distally and be caught in the filter. In the remaining 4 cases (67%), plaque protrusion remained after balloon dilatation alone, requiring insertion of an additional stent. In any event, it was possible to complete the procedure in all the cases developing plaque protrusion without any complication. In addition, there were no cases of stroke after the procedure. According to our experience, it seems possible to avoid complications in patients developing plaque protrusion if appropriate treatment is continued until disappearance of plaque protrusion. Aspiration seems to be one of the therapeutic options. However, aspiration cannot work in practice because aspiration devices or guiding catheters are smaller than the diameter of the stented artery and selective aspiration might be impossible. If the plaque protrusion still remains after additional stenting, surgical removal should be considered.6-8 In the field of coronary artery intervention, it has been reported that the use of IVUS can improve the outcome of treatment because it enables detection of insufficient stent dilatation.11,12 There are some reports that show IVUS is useful during CAS to evaluate plaque characteristics,13-16 or to assess stent expansion or apposition.13-17 However, to our knowledge, this is the first report that shows the usefulness of IVUS during CAS to detect plaque protrusion. In the present study, the detection rate of plaque protrusions was more precise

PLAQUE PROTRUSION DURING CAS

by IVUS at 7.8% (6/77) than by angiography 2.6% (2 of 77). The cases reported here had no plaque protrusion at the end of CAS procedure, and none had late stroke after the procedure. The detection of plaque protrusion and confirmation of no plaque protrusion by IVUS may have played a role in improving the outcome for late stroke complications. The limitations of this study were that it was conducted in a single center with small number of patients, and it was retrospective. A larger multicenter study is needed to confirm these results. Because there were no cases with positive plaque protrusion at the end of CAS procedure, the relationship between plaque protrusion and late stroke complications remains a hypothesis.

Conclusions With IVUS, detection rate of plaque protrusion was 7.8% during CAS procedures. The rate was higher than the incidence previously reported using only angiography. Plaque protrusions disappeared after additional ballooning or stenting. There were no incidents of stroke for the cases with plaque protrusion. There was no stroke after procedure in all. These results suggest that periprocedural stroke can be reduced with adequate management of the patients with plaque protrusion. IVUS usage is worth considering for detection of plaque protrusion and to reduce complications during CAS.

References 1. Mas JL, Chatellier G, Beyssen B, et al. Endarterectomy versus stenting in patients with symptomatic severe carotid stenosis. N Engl J Med 2006;355:1660-1671. 2. Ringleb PA, Allenberg J, Bruckmann H, et al. 30 day results from the SPACE trial of stent-protected angioplasty versus carotid endarterectomy in symptomatic patients: a randomised non-inferiority trial. Lancet 2006; 368:1239-1247. 3. Brott TG, Hobson RW 2nd, Howard G, et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis. N Engl J Med 2010;363:11-23. 4. Bosiers M, de Donato G, Deloose K, et al. Does free cell area influence the outcome in carotid artery stenting? Eur J Vasc Endovasc Surg 2007;33:135-141. discussion 42-3.

2625 5. Ikari Y, Misumi K, Yokoi H, et al. Initial results of carotid artery stenting in Japan. Cardiovasc Interv Ther 2013; 28:37-44. 6. Ferrero E, Ferri M, Viazzo A, et al. Carotid stent removal of symptomatic plaque protrusion after carotid angioplasty stenting. Interact Cardiovasc Thorac Surg 2010; 11:254-256. 7. Takigawa T, Matsumaru Y, Kubo T, et al. Recurrent subacute in-stent restenosis after carotid artery stenting due to plaque protrusion. Neurol Med Chir (Tokyo) 2009;49:413-417. 8. Setacci C, de Donato G, Setacci F, et al. Surgical management of acute carotid thrombosis after carotid stenting: a report of three cases. J Vasc Surg 2005;42:993-996. 9. Aikawa H, Kodama T, Nii K, et al. Intraprocedural plaque protrusion resulting in cerebral embolism during carotid angioplasty with stenting. Radiat Med 2008;26:318-323. 10. Ogata N, Shinozaki N, Ikari Y. Potential cause of delayed strokes following carotid artery stenting. Cardiovasc Interv Ther 2013;29:52-54. 11. Oemrawsingh PV, Mintz GS, Schalij MJ, et al. Intravascular ultrasound guidance improves angiographic and clinical outcome of stent implantation for long coronary artery stenoses: final results of a randomized comparison with angiographic guidance (TULIP Study). Circulation 2003;107:62-67. 12. Casella G, Klauss V, Ottani F, et al. Impact of intravascular ultrasound-guided stenting on long-term clinical outcome: a meta-analysis of available studies comparing intravascular ultrasound-guided and angiographically guided stenting. Catheter Cardiovasc Interv 2003;59: 314-321. 13. Tresukosol D, Wongpraparut N, Lirdvilai T. The value of intravascular ultrasound-facilitated internal carotid artery stenting in a patient with heavily calcified and ambiguous common carotid artery stenosis. J Invasive Cardiol 2007;19:E203-E206. 14. Clark DJ, Lessio S, O’Donoghue M, et al. Mechanisms and predictors of carotid artery stent restenosis: a serial intravascular ultrasound study. J Am Coll Cardiol 2006; 47:2390-2396. 15. Wehman JC, Holmes DR Jr, Ecker RD, et al. Intravascular ultrasound identification of intraluminal embolic plaque material during carotid angioplasty with stenting. Catheter Cardiovasc Interv 2006;68:853-857. 16. Clark DJ, Lessio S, O’Donoghue M, et al. Safety and utility of intravascular ultrasound-guided carotid artery stenting. Catheter Cardiovasc Interv 2004;63:355-362. 17. Wilson EP, White RA, Kopchok GE. Utility of intravascular ultrasound in carotid stenting. J Endovasc Surg 1996;3:63-68.

Plaque protrusion detected by intravascular ultrasound during carotid artery stenting.

Stroke is a major complication of carotid artery stenting (CAS) that can occur during the procedure and for up to 30 days after the procedure in the l...
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