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In long-term follow-up, patients with moderate/severe CRI had a higher risk of death (7.6% vs 0.55%, p ¼ 0.002) when GFR was used in the analysis; and, similarly, symptomatic patients with moderate/severe CRI had a higher chance of MAE (18.8% vs 5.7%, p ¼ 0.026). However, these differences were not significant when serum creatinine was used as the marker for renal function. A Kaplan-Meier curve analysis also showed that symptomatic patients with moderate/severe CRI had significantly lower rates of freedom from MAE at 3 years using the GFR (46% vs 81%). There is a potential limiting bias in our study. Patients with CRI are more likely to be admitted for preprocedure hydration and contrast nephropathy prophylaxis. Similarly, the interventionalist is more likely to use contrast more judiciously in these patients. Unfortunately, not all of the data regarding contrast nephropathy prophylaxis and the amount of contrast used were available to us. There were also a limited number of patients with serum creatinine > 3.0 mg/dL; therefore, we combined the late outcomes for patients with moderate and severe CRI and compared them with patients with normal renal functions.
CONCLUSIONS Chronic renal insufficiency had no effect on perioperative outcomes after CAS, whether GFR or serum creatinine was used to determine renal function. The GFR was more sensitive, however, in predicting late MAE, especially in symptomatic patients. Carotid artery stenting can be performed in patients with moderate/severe CRI with satisfactory perioperative results. However, the late death rate was significantly higher in these patients, and late MAEs were also significantly high, especially in symptomatic patients, and should be regarded when considering CAS in these patients. Author Contributions Study conception and design: AbuRahma Acquisition of data: Alhalbouni, Abu-Halimah, Stone Analysis and interpretation of data: AbuRahma, Dean Drafting of manuscript: AbuRahma, Stone Critical revision: AbuRahma, Stone REFERENCES 1. Mantese VA, Timaran CH, Chiu D, et al. The carotid revascularization endarterectomy versus stenting trial (CREST): Stenting versus carotid endarterectomy for carotid disease. Stroke 2010;41:S31eS34. 2. Yadav JS, Wholey MH, Kuntz RE, et al. Protected carotidartery stenting versus endarterectomy in high-risk patients. N Engl J Med 2004;351:1493e1501.
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3. Sidawy AN, Aidinian G, Johnson ON III, et al. Effect of chronic renal insufficiency on outcomes of carotid endarterectomy. J Vasc Surg 2008;48:1423e1430. 4. Kang JL, Chung TK, Lancaster RT, et al. Outcomes after carotid endarterectomy: Is there a high-risk population? A National Surgical Quality Improvement Program report. J Vasc Surg 2009;49:331e338. 5. Plecha EJ, King TA, Pitluk HC, Rubin JR. Risk assessment in patients undergoing carotid endarterectomy. J Cardiovasc Surg 1993;1:30e32. 6. Hamdan AD, Pomposelli FB, Gibbons GW, et al. Renal insufficiency and altered postoperative risk in carotid endarterectomy. J Vasc Surg 1999;29:1006e1011. 7. Sternbergh WC III, Garrad CL, Gonze MD, et al. Carotid endarterectomy in patients with significant renal dysfunction. J Vasc Surg 1999;29:672e677. 8. Shekherdimian RT, Golchet P, Moore W. The safety of carotid endarterectomy in patients with preoperative renal dysfunction. Ann Vasc Surg 2002;16:176e180. 9. Ascher E, Marks NA, Schutzer RW, Hingorani AP. Carotid endarterectomy in patients with chronic renal insufficiency: a recent series of 184 cases. J Vasc Surg 2005;41:24e29. 10. Debing E, van den Brande P. Chronic renal insufficiency and risk of early mortality in patients undergoing carotid endarterectomy. Ann Vasc Surg 2006;20:609e613. 11. Tarakji A, McConaughy A, Nicholas GG. The risk of carotid endarterectomy in patients with chronic renal insufficiency. Curr Surg 2006;63:326e329. 12. Protack CD, Bakken AM, Saad WE, Davies MG. Influence of chronic renal insufficiency on outcomes following carotid revascularization. Arch Surg 2011;146:1135e1141. 13. Jackson BM, English SJ, Fairman RM, et al. Carotid artery stenting: identification of risk factors for poor outcomes. J Vasc Surg 2008;48:74e79. 14. Saw J, Gurm HS, Fathi RB, et al. Effect of chronic kidney disease on outcomes after carotid artery stenting. Am J Cardiol 2004;94:1093e1096.
Discussion DR SPENCE TAYLOR (Greenville, SC): As we have become accustomed, the group from West Virginia has again “moved the ball forward” clinically, this time in the area of carotid intervention, and specifically, carotid stenting in patients with chronic kidney disease. There appear to be 2 significant findings from this wellpresented study. First, carotid stenting appears to be safe in patients with underlying renal failure, a finding most might find counterintuitive. Second, patients with underlying renal failure who undergo carotid stenting have more late major adverse events than patients without renal failure, a finding that is intuitive. My only critique of the study relates to the study cohort size. Although there were more than 300 patients in the study who underwent carotid stenting, less than 20% had renal insufficiency which, of course, was the index variable studied. Although there is little that Dr AbuRahma could do about this, the small sample size does make the study susceptible for type 2 statistical error, which may indeed be present. I have 3 questions.
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1. Can you tell me what happened to the renal function status of the patients with kidney disease who underwent carotid stenting? Was there significant contrast nephropathy? 2. The opportunity to be discussing a paper by Dr AbuRahma provides an opportunity to “pick his brain” on how he manages controversial vascular problems. Your cohort of more than 300 carotid stentings is impressive. In your practice, who receives carotid endarterectomy and who receives a carotid stent? 3. Last, the prevailing data in the literature suggest that certain highrisk patient cohorts may fare better after carotid stenting than after open carotid endarterectomy. Your study may have exposed an additional group of high-risk patients; namely, those with renal insufficiency, who may benefit from this less invasive intervention. That said, Dr John Eidt, a new addition to our Greenville vascular group, recently gave grand rounds and reviewed the literature on asymptomatic carotid stenosis. Unlike the findings of the Asymptomatic Carotid Artery Stenosis (ACAS) trial published 20 years ago, in which the annual risk of stroke for a patient with an asymptomatic hemodynamically significant carotid stenosis was approximately 5% per year, contemporary series in the age of statin therapy suggest that risk may now be closer to 1% per year. This also suggests that surgery for asymptomatic carotid stenosis may go the route of the extracranial-intracranial bypass and toward the surgical museum of retired procedures. You allude to this in your manuscript, but let me ask you directly: Is there really any benefit of intervention on asymptomatic carotid stenosis, especially in patients with chronic kidney disease? DR ERIC ENDEAN (Lexington, KY): It would appear that they are asking 2 questions. Does abnormal renal function have an effect on outcomes either early or late? And, if so, which is the better predictor, serum creatinine or estimated glomerular filtration rate? Essentially, they found that renal insufficiency had no effect on outcome except in one group of patients, that being the long-term outcome of symptomatic patients. I have a number of questions for the authors. First, all the patients included in this report had been enrolled in a number of carotid artery stent trials. Could you give us some information about these trials? For example, can you tell us who performed the stenting procedure? Were they radiologists, cardiologists, or vascular surgeons? Were these randomized trials? Were there exclusion criteria for the trials? Specifically, were patients with severe renal insufficiency excluded? And how were the patients treated if they were excluded? Second, although this study focuses on carotid stenting, could you provide us with information regarding the effect of renal insufficiency on the outcomes of patients who had carotid endarterectomy during this same time period? Third, in the manuscript, the authors cited a number of reports that document renal insufficiency as being associated with adverse outcomes for treatment of carotid disease. Could you speculate on why this study seems to differ from some of these other reports? Fourth, in patients with abnormal renal function, were there any patients who had acute kidney injury? Finally, given your extensive experience in treating carotid disease, what would you recommend for a 75-year-old woman who
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has a high-grade symptomatic carotid lesion and also has a creatinine of 4.0 mg/dL? DR JOHN RICOTTA (Washington, DC): Do you have anything on the plaque characteristics of your symptomatic patients with chronic renal insufficiency and how they compare to those in the symptomatic patients who did not have chronic renal insufficiency? DR RUTH BUSH (Round Rock, TX): I just have a logistical question. Do you do preoperative imaging, such as CT angiography or magnetic resonance angiography (MRA), on these patients who have renal insufficiency, and then what do you do in the operating room to decrease contrast usage? Do you cut the contrast in half? Do you use intravascular ultrasound? DR ALI ABURAHMA: Every member of our group treated these patients with a similar protocol. Patients were preadmitted for hydration, given Mucomyst and bicarb, and we judicially minimized the amount of contrast used. There were a few patients who had a temporary rise in their creatinine for a few days. Contrast nephropathy is something you need to watch for; however, if you are careful, carotid artery stenting (CAS) can be done with a minimum amount of contrast. As for the indication for carotid intervention (carotid endarterectomy [CEA] vs CAS), presently CAS is done at our institution only for symptomatic patients who are considered high-risk for CEA, either anatomically or physiologically, as defined by Medicare/Centers for Medicare and Medicaid Services criteria. The CAS is also done for high-risk (80%) asymptomatic patients at our institution who are participating in clinical trials. In regard to whether or not medical therapy is the appropriate therapy for asymptomatic stenosis, I understand your concern regarding this issue. As a matter of fact, similar concerns were raised in the VEITHsymposium in New York in November 2013, where several authorities addressed this issue. Presently, there is no level 1 evidence to support that optimum medical therapy alone is better than carotid intervention, specifically CEA. I am hoping that within the next few years, some of the randomized trials will address this issue once and for all. My personal bias is that CEA is still a good option for asymptomatic patients with 70% stenosis in healthy individuals, specifically, with a life span of at least 3 to 5 years in good hands. In regard to the questions and comments by Dr Endean, first, about which patients were enrolled in these CAS trials, our program participated in at least 8 CAS trials over the past 10 to 15 years, and each carotid trial had its own criteria for inclusion and exclusion; therefore, it would be difficult for me to specify each trial’s criteria in this limited amount of time. Concerning the outcomes of CEA in patients with chronic renal insufficiency, this was addressed in our previous meeting in Florida last year, where we presented the early results (30-day perioperative outcomes on patients with chronic renal insufficiency) and the long-term outcomes were also analyzed and will be presented at a future meeting. However, the results were somewhat similar to the outcomes in patients with CAS, as indicated in this presentation.
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Finally, patients who had an acute kidney injury were addressed earlier. In regard to your question of a 75-year-old woman who had a high-grade symptomatic carotid lesion with a creatinine of 4.0 mg/dL, my best advice for this patient would be a CEA at this stage. To answer Dr John Ricotta’s question, carotid plaque characteristics were not analyzed in this study.
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In regard to the question by Dr Ruth Bush, we do not get preoperative imaging, other than duplex ultrasound in asymptomatic patients, particularly if the duplex ultrasound was done at our own vascular laboratory. Other preoperative imaging, eg, CT or MRA, is done in symptomatic patients. However, in patients with chronic renal insufficiency, we rely more on MRA than CT. At this time we do not routinely do intravascular ultrasounds on these patients.