Carotid artery stenting is safe and associated with comparable outcomes in men and women
Article Outline
Objective
Historically, large randomized controlled studies looking at carotid endarterectomy (CEA) have indicated an increased perioperative risk for women when gender subgroup analysis was performed. However, the outcomes of carotid stenting in women as compared to men have not been adequately investigated. We sought to compare the safety and efficacy of carotid angioplasty and stenting (CAS) when performed in women as compared to men.
Methods
Procedures, complications, demographics, co-morbidities, and follow-up data from carotid stenting procedures performed in a bi-campus division were entered into a prospective database and then retrospectively supplemented with stored angiographic image data and reviewed. Arterial anatomic characteristics evaluated using angiographic images were: common carotid/internal carotid lesion length ratio, common carotid/internal carotid diameter, index lesion length, common carotid/internal carotid artery tortuosity, and lesion and aortic arch calcification. Outcomes compared included groin complications, postoperative pressor requirements, length of stay, restenosis, stroke, myocardial infarction (MI), and death.
Results
Between 2003 and 2008, 228 patients underwent 238 procedures. Cerebral protection devices and self-expanding stents were placed in all patients. A total of 97 percutaneous interventions performed in 93 women were compared with 141 interventions in 135 men. Mean age in women was 71.8 ± 9.2 years, in men was 72.2 ± 9.1 years (P > .99); 44.3% of women and 34.7% of men had symptomatic disease (P = .14). Preoperative demographics and co-morbidities did not differ significantly between genders, with the exception of hypertension (83.0% of males vs 96.7% of females, P = .001), and history of coronary artery bypass grafting (31.8% of males vs 16.1% of females, P = .01). There were no significant differences seen in anatomic arterial characteristics, though there was a trend towards women having larger internal carotid to common carotid diameter ratios (0.65 vs 0.62) and more plaques isolated to the common carotid segment (9.5% vs 6.9%). There were no significant differences seen in overall 30-day peri-procedural stroke rate (2.1% in women and 4.2% in men, P = .48), death rate (0 % vs 0.7%, P > .99), or cardiac events (3.2% vs 0.7%, P = .3). The combined 30-day stroke, death, and MI rate was 5.7% for males compared to 5.4% for females (P > .99). There were no differences observed in the long-term survival, stroke-free survival, or restenosis between genders.
Conclusion
Despite previous concerns over adverse outcomes in women undergoing carotid endarterectomy, from our data, carotid stenting appears to be a safe modality in women with equivalent outcomes when compared to men.
Carotid artery interventions aim to prevent cerebrovascular events in the distribution of the internal carotid artery (ICA). For the past 2 decades, large-scale trials have studied when to intervene when faced with extra-cranial carotid stenoses.1, 2, 3, 4, 5 As new endovascular procedures are being developed for the treatment of carotid lesions, carotid angioplasty and stenting (CAS) trials are attempting to define the role of stenting in the management of these lesions.6, 7, 8, 9 Many of the earlier investigations into carotid interventions have failed to adequately analyze the effect of gender on the outcome of the procedure, or failed to show a benefit for women, calling into question the utility of these interventions in female patients. The initial reports of the two most frequently-cited trials regarding the use of carotid endarterectomy (CEA) in symptomatic patients, the North American Symptomatic Carotid Endarterectomy Trial (NASCET), and the European Carotid Surgery Trial (ECST), both omitted subgroup analysis with regard to gender.2, 3 Additionally, in both trials, one-third or fewer of the patients were females. Subgroup analysis of the combined dataset for these studies via the Carotid Endarterectomy Trialists' Collaboration (CETC), showed women with ≥70% stenosis did benefit from CEA, but only if they underwent surgery within 2 weeks of their symptoms, compared to men who benefited for longer than 12 weeks.10, 11
The largest trials supporting the use of CEA in asymptomatic patients, the VA Cooperative Trial, the Asymptomatic Carotid Atherosclerosis Study (ACAS), and the Asymptomatic Carotid Surgery Trial (ACST) also failed to support CEA in asymptomatic women. The VA Cooperative Trial studied only men, the ACAS failed to show a benefit due to an almost threefold higher perioperative complication rate in women, and the ACST long-term non-perioperative risk reduction gained by women (4.1%) was made largely irrelevant when compared to the perioperative stroke and death rate (3.8%).1, 4, 5 In summary, all of the large carotid endarterectomy trials showed decreased or no benefit in women when compared to men mostly because these trials were underpowered to show any utility in the relatively small female population studied, and secondly because the long-term benefit was undermined by the high perioperative morbidity seen in women.
With regard to carotid stenting, the Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial, has recently reported long-term non-inferiority of CAS compared to CEA.6, 12 However, it too did not separately analyze outcomes for women, and only one-third of those patients were female. Even fewer (<30%) of the patients were female in the Stent-Protected Percutaneous Angioplasty Versus Carotid Endarterectomy (SPACE) trial, and the women suffered a larger difference in periprocedural complication rates between CAS and CEA (1.71%) than men (0.04%).7 The Endarterectomy vs Stenting in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) trial also had <30% females, and did not make any gender-specific observations.8
The lack of data in major trials regarding the benefit of carotid interventions in women prompted our group to study the outcomes of CAS in women. We therefore sought to investigate the safety, feasibility, and efficacy of the carotid angioplasty and stenting experience in our division with regard to gender.
Methods
All patients who underwent carotid angioplasty and stenting between November 2002 and March 2008 at New York Presbyterian Hospital were included in this study. A total of 228 patients underwent 238 procedures involving cerebral angiography, carotid angioplasty, and trans-catheter carotid stent deployment.
All patients underwent CAS for symptomatic stenoses >50% or asymptomatic lesions >80% and were considered to be at an increased risk for standard CEA. High-risk status was determined by either medical comorbidities (Goldman class II or III,13 American Society of Anesthesiologists [ASA] class III or IV14), severe pulmonary disease, or anatomic factors including history of neck irradiation, spinal immobility with an inability to flex the neck beyond neutral or a kyphotic deformity, prior ipsilateral CEA, contralateral carotid occlusion, or high lesion location in the ICA. The degree of stenosis was determined by preoperative duplex ultrasound scan (using the University of Washington criteria),15, 16 magnetic resonance angiography (MRA), or cerebral angiography. Preoperative lesion characteristics and postoperative surveillance were evaluated with duplex ultrasonography scan in our non-invasive vascular laboratories by ultrasound technicians experienced in carotid imaging. Vascular surgeons provided interpretation of the results of the ultrasound imaging and cerebral angiography; radiologists provided interpretation of the MRA.
Contraindications to stenting were subject to operator discretion and included excessive calcification of the target lesion, severe tortuosity of the cerebral vasculature, contraindication to administration of plavix, and small internal carotid diameter precluding placement of a stent.
In order to monitor the patient's neurologic status continuously throughout the procedure, the procedures were performed using local anesthesia without sedation. The common femoral artery was used to obtain vascular access and cerebral angiography was performed to confirm the degree of carotid stenosis. Unfractionated heparin was administered intravenously to maintain an activated clotting time of >250 seconds. The patients were placed on clopidogrel 75 mg for 5 days prior to stenting, or 300 mg loading dose 4 hours prior to carotid stenting.
A wide range of stents and protection devices were used, reflecting the evolution of available devices and involvement in clinical trials (Table I, Table II). Cerebral protection devices and self-expanding stents were placed in all patients. The lesions were routinely pre- and post-dilated with a rapid exchange system angioplasty balloon chosen during the procedure at the operator's discretion (Table I). The stent and angioplasty balloon lengths and diameters employed for each patient were retrospectively collected as available and entered into our database for review. Until 2005, 0.5 mg of atropine was routinely administered intravenously regardless of the nature of the lesion, prior to pre-dilation to minimize the parasympathetic response. After 2005, atropine was replaced with 0.2 to 0.4 mg of glycopyrrholate, given in a similar manner. All patients were maintained on 325 mg of aspirin daily and 75 mg of clopidogrel during the postoperative period. Clopidogrel was discontinued 30 days after the procedure unless there were other reasons necessitating its continuation. Patients were maintained indefinitely on a daily dose of aspirin.
Table I. Carotid stent sizes and angioplasty balloon characteristics
| Characteristics | Male | Female | P value |
|---|---|---|---|
| Pre-dilatation balloon diameter (mm) | n = 125 | n = 83 | |
 2-2.5 | 3 | 3 | .68 |
| 3-3.5 | 11 | 5 | .59 |
| 4 | 111 | 70 | .40 |
| 5-6 | 0 | 5 | .009 |
| Pre-dilatation balloon length (mm) | n = 68 | n = 38 | |
| 20 | 24 | 21 | .06 |
| 30-35 | 1 | 1 | >.99 |
| 40 | 43 | 16 | .04 |
| Stent diameter (mm) | n = 96 | n = 64 | |
| Tapered | n = 31 | n = 24 | .50 |
| 6 × 8 | 6 | 6 | .54 |
| 7 × 10 | 25 | 15 | .85 |
| Other (7 × 7, 7 × 9, 8 × 10) | 0 | 3(1each) | .06 |
| Straight | n = 65 | n = 40 | .50 |
| 5 | 3 | 1 | >.99 |
| 6 | 2 | 1 | >.99 |
| 7 | 2 | 6 | .051 |
| 8 | 20 | 15 | .53 |
| 9 | 12 | 4 | .28 |
| 10 | 26 | 13 | .53 |
| Stent length (mm) | n = 86 | n = 60 | |
| ≤30 | 61 | 50 | .11 |
| ≤40 | 25 | 10 | .11 |
| Post-dilatation balloon diameter (mm) | n = 128 | n = 85 | |
| 4 | 2 | 2 | >.99 |
| 5 | 21 | 56 | 1.88 e-13 |
| 5.5 | 95 | 25 | 1.07 e-10 |
| 6 | 9 | 1 | .053 |
| 7 | 1 | 1 | >.99 |
| Post-dilatation balloon length (mm) | n = 69 | n = 46 | |
| 20 | 48 | 36 | .39 |
| 30 | 8 | 0 | .02 |
| 40 | 13 | 9 | >.99 |
| 50-60 | 0 | 1 | .04 |
Table II. Carotid stent systems and cerebral protection devices
| Characteristics | Male | Female | P value |
|---|---|---|---|
| Stent | n = 141 | n = 97 | |
| Closed Cell | n=41(29.1%) | n=27(27.8%) | .88 |
| Wallstent | 23(56.1%) | 18(66.7%) | .45 |
| Nex Stent | 17(41.5%) | 6(22.2%) | .12 |
| Xact | 1(2.4%) | 3(11.1%) | .30 |
| Open Cell | n=94(66.7%) | n=67(69.1%) | .78 |
| Precise | 23(24.5%) | 12(17.9%) | .34 |
| Acculink | 64(68.1%) | 47(70.1%) | .86 |
| Maverick (exponent) | 1(1.1%) | 2(3.0%) | .57 |
| Vivex | 4(4.2%) | 4(6.0%) | .72 |
| Protege | 2(2.1%) | 2(3.0%) | >.99 |
| Unknown | n = 6(4.2%) | n = 3(3.1%) | .74 |
| Protection Device | n = 141 | n = 97 | |
| Percusurge | 16(11.3%) | 21(21.6%) | .04 |
| Epi Filter Wire | 44(31.2%) | 22(22.7%) | .18 |
| Accunet | 49(34.7%) | 37(38.1%) | .68 |
| Angioguard | 23(16.3%) | 9(9.3%) | .13 |
| Emboshield | 7(5.0%) | 6(6.2%) | .77 |
| Spider Filter | 2(1.4%) | 2(2.1%) | >.99 |
Angiographic data was retrospectively reviewed and recorded on a Leonardo workstation (Siemens Medical, Munich, Germany). Image measurements were quantified by calibrating the system using a table-object distance calibration, supplied as a software function of the workstation which calculates a calibration factor on the basis of image geometry. Arterial anatomic characteristics evaluated using angiographic images were: aortic arch elongation classification, aortic arch calcification, index lesion calcification, common carotid diameter, internal carotid diameter, index lesion length, common carotid/internal carotid lesion length ratio, common carotid tortuosity, and internal carotid tortuosity. Internal carotid diameter was measured at the first point in the artery distal to the lesion at which the arterial walls became parallel. The aortic arch elongation classification was defined by the location of the origin of the arch vessels: arising from the top of the arch (class I), between the parallel planes delineated by the outer and inner curves of the arch (class II), and caudal to the inner surface of the arch or off the ascending aorta (class III).17 Aortic arch calcification was classified as no calcium present, single arch surface with calcified irregularity (mild to moderate), or significant calcification of both luminal arch surfaces (severe). Lesion calcification was classified in a similar manner with regard to the luminal surfaces of the index lesion (none, mild-moderate, severe). Vessel tortuosity was graded in three groups: vessels with <30 degree angulation from the centerline of blood flow, 30-60 degree angulation, and >60 degree angulation. A bovine arch configuration was defined as the innominate artery and left common carotid artery either originating from a common orifice, or the left common carotid artery originating as a branch of the innominate artery. Of these anatomic features, the individual surgeon recorded the degree of stenosis of the index lesion, the presence and degree of lesion calcification, and the anatomic specifics of the aortic arch at the time of the procedure in a prospective manner. The authors of this paper collected other angiographic data retrospectively from existing archived angiographic images.
Procedures, complications, demographics, co-morbidities, angiographic characteristics, and follow-up data were entered into a prospective database for review (Microsoft Excel, Microsoft Corp, Redmond, Wash). Categorical data was compared between groups using the Fisher's Exact Test. Kaplan-Meier curves for survival, stroke-free survival, and long-term carotid patency were compared using the log rank test.
Results
Demographics
A total of 238 interventions were performed on 228 patients from 2003 to 2008 at New York Presbyterian Hospital. A total of 141 interventions were performed on 135 males, and 97 interventions were performed on 93 females. Preoperative demographics collected are listed in Table III. The mean age was 72.2 ± 9.1 years for males (range, 51-93), and 71.8 ± 9.2 years for females (range, 46-94) (P > .99). Forty-nine males (34.7%) and 43 females (44.3%) were symptomatic at the time of their presentation (P = .14). Only the presence of hypertension, history of smoking, and the history of a previous coronary artery bypass grafting (CABG) were found to occur in significantly different frequencies between men and women. Women were more likely to have hypertension compared to men (96.7% vs 83.0%, P = .001). Interestingly, while there was no statistically significant difference in the history of coronary disease (defined as a prior myocardial infarction [MI] or acute coronary event, positive stress test, angina, ischemic cardiomyopathy, or documented cardiac catheterization findings), men were more likely than women to have undergone CABG (31.8% vs 16.1%, P = .01). Men were also more likely to be smokers (65.9% vs 51.6%, P = .04).
Table III. Patient demographics
| Males | Females | P value | |
|---|---|---|---|
| Mean age (years) | 72.2±9.1 | 71.8±9.2 | >.99 |
| Hypertension | 112(83.0%) | 90(96.7%) | .001 |
| Hypercholesterolemia | 89(65.9%) | 68(73.1%) | .31 |
| CABG | 43(31.8%) | 15(16.1%) | .01 |
| Coronary disease | 89(65.9%) | 50(53.7%) | .07 |
| Previous MI | 30(22.2%) | 18(19.3%) | .62 |
| Diabetes | 38(28.1%) | 29(31.1%) | .66 |
| PVD | 27(20.0%) | 20(21.5%) | .87 |
| Smoker | 89(65.9%) | 48(51.6%) | .04 |
| Cancer history | 38(28.1%) | 20(21.5%) | .28 |
| Previous ipsilateral CEA | 13(9.6%) | 16(16.4%) | .11 |
| Previous contralateral CEA | 8(5.9%) | 9(9.2%) | .31 |
| Symptomatic | 49(34.7%) | 43(44.3%) | .14 |
| Contralateral occlusion | 15(10.6%) | 9(9.3%) | .83 |
Angiographic characteristics
Prospective angiographic data was collected and supplemented with retrospective angiographic review, and was available as follows: common carotid tortuosity for 186 procedures, internal carotid tortuosity for 208 procedures, lesion calcification for 216 procedures, arch elongation type for 223 procedures, bovine arch configuration for 226 procedures, and arch calcification for 211 procedures. Retrospective angiographic review was used when available to obtain the internal and common carotid artery diameters, the internal to common carotid artery diameter ratio, and the extent of the lesion distribution for 149 procedures. There were no significant differences for any of these traits between men and women in our cohort. The mean ICA diameter was 4.2 ± 1.0 mm for males vs 3.9 ± 0.8 mm for females (P > .99). Women were more likely than men to have a carotid lesion confined with the common carotid, however, this trend did not become statistically significant (9.5% vs 6.9% P = .76) (Table IV).
Table IV. Angiographic lesion characteristics
| Characteristics | Males | Females | P value |
|---|---|---|---|
| Lesion calcium | |||
| None | 63(48.8%) | 46(52.8%) | .58 |
| Mild-moderate | 43(33.3%) | 26(29.9%) | .65 |
| Severe | 23(17.8%) | 15(17.2%) | >.99 |
| Mean ICA diameter (mm) | 4.2±1.0 | 3.9±0.8 | >.99 |
| Mean CCA diameter (mm) | 6.9±1.4 | 6.0±1.1 | .77 |
| ICA/CCA diameter ratio | 0.62 | 0.65 | >.99 |
| Lesion distribution | |||
| CCA only | 6(6.9%) | 6(9.5%) | .76 |
| Mean length (mm) | 17.4±6.5(8.7-24.5) | 14.5±8.4(4.6-27.6) | >.99 |
| CCA + ICA | 30(34.8%) | 20(31.7%) | .72 |
| Mean length (mm) | 15.0±6.1(2.3-26.6) | 15.4±6.0(8.6-28.7) | .48 |
| ICA only | 50(58.1%) | 37(58.7%) | >.99 |
| Mean length (mm) | 10.9±4.8(1.6-22.6) | 9.5±5.3(1.7-26.2) | >.99 |
| Length in ICA/total length | 0.78 | 0.79 | >.99 |
| Common carotid tortuosity | |||
| 0-30 | 74(64.9%) | 49(63.6%) | .87 |
| 30-60 | 25(21.9%) | 23(29.8%) | .23 |
| >60 | 10(8.7%) | 5(6.4%) | .78 |
| Internal carotid tortuosity | |||
| 0-30 | 49(40.1%) | 24(27.5%) | .07 |
| 30-60 | 36(29.5%) | 31(35.6%) | .37 |
| >60 | 37(30.3%) | 32(36.7%) | .37 |
| Arch calcium | |||
| None | 79(63.2%) | 52(60.4%) | .77 |
| Mild-mod | 36(28.8%) | 25(29.0%) | >.99 |
| Severe | 10(8.0%) | 9(10.4%) | .62 |
| Bovine arch configuration | 29(21.8%) | 25(26.8%) | .42 |
| Arch type | |||
| 1 | 56(44.8%) | 39(42.8%) | .78 |
| 2 | 57(45.6%) | 45(49.6%) | .58 |
| 3 | 12(9.6%) | 7(7.6%) | .80 |
Retrospective analysis of the stent systems and cerebral protection devices employed revealed no difference between genders in the use of straight vs tapered stents, or closed vs open cell designed stent systems (Table I, Table II). Women were significantly more likely to have had a 5 mm post-dilatation balloon employed vs men (56 vs 21, P < .0001) while men were more likely to have had a 5.5 mm post-dilatation balloon employed vs women (95 vs 25, P < .0001) (Table I).
Procedural outcomes
Postoperative data is listed in Table V. Local groin complications occurred with low frequency in both men and women. Men had five hematomas, and females had four (3.5% vs 4.1%, P > .99). Pseudoaneurysm occurred in one male and one female (0.7% vs 0.1%, P > .99). There were six strokes in males (4.2%), including four minor strokes and two major strokes, and two strokes in females (2.1%), including one minor stroke and one major stroke (P = .48 for men vs women). One minor stroke occurred in a male who also went on to suffer an MI, and one major stroke in a male resulted in a mortality. The 30-day mortality rate in our series for all patients was 0.4%, with one death occurring in a male, and no deaths occurring in females. Three females (3.1%) suffered an MI, compared to one male (0.7%), (P = .3). The combined stroke, death, and MI rate was 5.7% for males compared to 5.4% for females (P > .99). There was no difference in the requirement for postoperative hemodynamic pressor therapy related to carotid bulb insult (defined as requiring an infusion of epinephrine, norepinephrine, dopamine, or phenylephrine to maintain adequate arterial blood pressure at the discretion of the operator for any length of time), or postoperative length of stay.
Table V. Postoperative patient data
| Males | Females | P value | |
|---|---|---|---|
| Hematoma | 5(3.5%) | 4(4.1%) | >.99 |
| Pseudoaneurysm | 1(0.7%) | 1(0.1%) | >.99 |
| Stroke | 6(4.2%) | 2(2.1%) | .48 |
| 4 minor, 2 major | 1 minor, 1 major | ||
| Death | 1(0.7%) | 0 | >.99 |
| MI | 1(0.7%) | 3(3.2%) | .30 |
| Stroke/death/MI | 8(5.7%) | 5(5.4%) | >.99 |
| Postoperative pressors | 20(14.2%) | 17(17.5%) | .46 |
| Average LOS (days) | 2.0±1.6 | 1.6±1.3 | >.99 |
| LOS (1 day only) | 101(71.6%) | 67(69.0%) | >.99 |
Follow-up
Patients were followed with clinic visits and carotid duplex at 1 month postoperatively and then 3, 6, and 12 months postoperatively and yearly thereafter. Follow-up duplex scans were available for 111 of 141 males and for 72 of 97 females, with a mean follow-up time of 15.6 ± 15.6 months (range, 0 to 68 months). Kaplan-Meier analysis of duplex scan-assessed restenosis (>50% luminal reduction, also assessed using the University of Washington duplex scan criteria)15, 16 revealed no significant differences between men and women (Fig 1, P = .92). Only 1 male patient in the series (and no female patients) demonstrated a greater than 70% restenosis which occurred 7.5 months following his CAS. He remained asymptomatic and he underwent repeat CAS, which again progressed to greater than 70% stenosis in just 4 months after the second intervention, after which the patient was lost to follow-up.
Fig 1.
Kaplan-Meier plot of men versus women demonstrating greater than 50% restenosis by duplex ultrasonography scan following carotid angioplasty and stenting. There is no difference in long-term restenosis seen between genders (P = .92). CAS, Carotid artery stenting.
Mean clinical follow-up was 22.3 ± 17.4 months (range, 0 to 68 months). During our follow-up period, 24 men and 15 women died. One-year survival was 93.0% for men and 94.4% for women, and 3-year survival was 76.3% for men and 75.0% for women. Kaplan-Meier survival analysis demonstrated no difference in long-term survival between men and women (P = .47) (Fig 2).
Fig 2.
Kaplan-Meier survival curve following carotid angioplasty and stenting. There is no long-term survival difference between men and women (P = .47). CAS, Carotid artery stenting.
During the follow-up period, two women developed neurologic events. One patient experienced mild neurologic symptoms 15 months after the carotid intervention with symptoms largely improving with medical management. The second woman sustained an ischemic stroke manifested by upper and lower extremity paresis and aphasia 32 days after the carotid stenting. Thrombolytic treatment in another hospital led to a severely debilitating hemorrhagic stroke. The patient never recovered from the dense neurologic symptoms. One man experienced aphasia and paraplegia 2 years after the initial procedure due to an ipsilateral ischemic infarct. For both of the women and the man who developed late-onset neurologic symptoms, duplex ultrasonography scan verified stent patency after the onset of their symptoms. Kaplan-Meier analysis demonstrated no difference in stroke-free survival between men and women throughout our follow-up period (P = .48) (Fig 3).
Fig 3.
Kaplan-Meier stroke-free survival curve following angioplasty and stenting. There is no difference in long-term stroke free survival between men and women (P = .48). CAS, Carotid artery stenting.
Discussion
This study looked specifically at the outcomes at our institution of carotid angioplasty and stenting by gender. In our cohort, women undergoing CAS comprised a similar patient population as men and shared similar angiographic characteristics of their arteries and lesions as men. Compared to men, women had no statistically significant difference in technical outcomes from the procedure, with similar peri-procedural cardiovascular and neurologic event rates, procedure-associated mortality, short hospital lengths of stay, and low rates of local groin complications. Men were found to be more likely to have undergone CABG in our patient population. While a higher percentage of men presented with coronary disease, there was not a significant difference between genders. From our data it is unclear whether the observed disparity between the two genders in surgically treating patients with coronary disease actually reflects a different severity of coronary disease or a tendency to undertreat females with coronary disease.
In our cohort, we did not observe any statistically significant gender-associated difference in the plaque area or distribution. This contrasts with the findings of other authors. Indeed, Schulz and Rothwell18 showed that women had better carotid outflow ratios, with a larger internal carotid artery/common carotid artery (ICA/CCA) diameter ratio than men (0.67 vs 0.62), and men were more likely to have disease distal to the carotid bulb while women were more likely than men to have a stenotic lesion within the common carotid. Our study found women to have a larger ICA/CCA ratio as well (0.65 vs 0.62), however, this did not reach significance presumably in part due to our sample size (nearly one-eighth that of Schulz and Rothwell) and the fact that the previous study only examined vessels with less than a 50% stenosis (perhaps skewing their results). We also found women more likely than men to have a stenotic lesion localized in the common carotid (9.5% vs 6.9%), however, this trend did not become statistically significant (P = .76) likely due to the small sample for comparison and the fact that such lesions within the common carotid are technically more challenging and thus less favorable for carotid stenting. Iemolo et al19 studied gender differences in carotid plaques and stenosis, and found women to have more focal lesions when compared to men. We did not identify such differences in our study, again most likely due to selection bias since focal lesions are more preferable for angioplasty.
We also did not find a statistically significant difference in the mean diameter of the ICA between genders in our study (4.2 mm ± 1.0 for men vs 3.9 mm ± 0.8 for women, P > .99). Gender-related difference in internal carotid size has been reported in the existing literature: Goubergrits et al20 looked at post-mortem vessel casts of carotid arteries and did find smaller diameters in women for absolute measurements of the ICA, but that difference disappeared once normalized against the common carotid diameter. Smaller carotid arteries in women have also been confirmed clinically using ultrasound scans by other authors including Hansen et al21 and Williams et al.22 Our cohort represents a group of patients who received carotid stents, potentially excluding women with smaller internal carotid arteries who may have been unsuitable for carotid stenting. Despite our measured similarity in ICA diameters, women were significantly more likely to have had a 5 mm post-dilatation balloon employed vs men, while men were more likely to have had a 5.5 mm post-dilatation balloon employed vs women. The operator made the choice of post-dilatation balloon size at the time of the procedure, and this finding may be related to preconceived notions regarding the sizes of arteries between genders.
The large randomized trials that have looked at the efficacy of carotid endarterectomy in preventing stroke in both symptomatic and asymptomatic patients as emphasized above, have either failed to show a significant benefit for women, or failed to specifically analyze gender as a subgroup. NASCET and ECST did not initially report gender subgroup analysis.2, 3 The CETC analysis of symptomatic patients showed that men with ≥70% stenosis benefit from surgery even after 12 weeks, while women only benefit if operated on in less than 2 weeks after the onset of symptoms.11 The asymptomatic trials fared no better, with ACAS reporting a 5-year relative stroke-risk reduction for men of 66% (95% confidence interval [CI], 36% to 82%) and for women a statistically insignificant 17% 5-year relative stroke-risk reduction (95% CI, −96% to 65%).1 They attributed this discrepancy to the higher perioperative complication rate seen in women compared to men (3.6% vs 1.7%, P = .12), yet among patients not suffering a perioperative event, the relative stroke-risk reduction of 56% was still not significant for women (56%, 95% CI, −50% to 87%), despite a strong reduction for men of 79% (95% CI, 52% to 91%).1 ACST touted a long-term non-perioperative risk reduction for women of 4.1%, but when compared to the perioperative stroke and death rate of 3.8%, there seemed little benefit to CEA in asymptomatic women.5 This increased perioperative risk has also been demonstrated in retrospective single institution studies,23 while other groups have concluded that CEA is equally safe and beneficial in women as in men.24, 25, 26 Rockman et al27 demonstrated retrospectively that CEA could be performed safely with similarly low perioperative stroke rates for both genders (2.3% for men vs 2.4% for women, P = .92). Lee et al28 added support to this with their cohort of patients who also demonstrated the safety of performing CEA in asymptomatic females, and similar conclusions were made by Mattos et al,24 and Schneider et al.25 These studies were not randomized, and did not take into account the complication rate attributable to perioperative arteriography in the ACAS trial.
The SAPPHIRE trial was the first stenting trial to show non-inferiority of CAS to CEA in high-risk patients, but women were under-represented within the recruited population. Furthermore, the study did not analyze data or compare outcomes for gender subgroups.6, 12 Regarding regular-risk patients with a high degree of symptomatic carotid stenoses, the more recent SPACE and EVA 3-S trials not only failed to show non-inferiority, but also had significantly higher rates of stroke and death than contemporary series for endarterectomy.29 Women demonstrated a higher absolute risk difference between CAS and CEA than men for primary endpoint events in the SPACE trial 1.71 (90% CI = −3.63 to 6.53) vs 0.04 (90% CI = −2.80 to 2.86).7 Both trials have been criticized for not meeting the intended number of randomized patients, not utilizing cerebral protection devices for all patients, and for varying experience of the operators performing the interventions. From all of these randomized trials comparing stenting to endarterectomy, only the Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) is designed to provide gender-specific outcomes with subgroup analysis but it is ongoing for now.
Therefore, until we have such data from the CREST trial or other future randomized prospective studies, the unsettled debate regarding the safety and efficacy of carotid stenting and our gender-specific management strategy as interventionalists should be based on information derived from smaller existing trials and registries. As in our study, Roubin et al30 also found men and women to have similar peri-procedural complication rates (8.0% vs 5.9%, respectively; P = .4) when undergoing carotid stenting. Eskandari et al31 looked at 44 women and 123 men and had both a major and minor stroke rate of 1.1%, with no appreciable differences noted between genders, though the absolute numbers of strokes occurring between the genders were not detailed. Park et al32 retrospectively looked at 42 women and 47 men undergoing carotid stenting and 40 women and 53 men undergoing carotid endarterectomy during the same period. They reported a 0% perioperative stroke rate in men and 2% in women, but this difference did not reach statistical significance. They had no deaths and no coronary events in the carotid stenting group. Interestingly they found no statistically significant difference between genders in any of the outcomes in the carotid endarterectomy arm of the study, although their reported incidence of MI after endarterectomy was 2% for men and 5% for women.
The addition of this larger cohort of patients in our study strengthens the findings of these previous studies with similar results. Eskandari also observed higher rates of clinically significant restenosis in women (all three observed lesions in their study occurred in females), which was not supported by our findings. In our opinion, although there is significant evidence that carotid endarterectomy in women is strongly associated with higher rates of restenosis, this might not hold true for carotid stenting.33, 34 Women have been shown to have better outflow to inflow ratios and higher carotid velocities than men.18, 35, 36 Both of these features should theoretically have a negative impact on the development of restenosis after stenting, but this needs further investigation. Finally, our results agree with the data collected and published in the ongoing Italian and German Registry: In 2007 the published data from CAS procedures performed in 179 women and 516 men showed no statistically significant difference in perioperative major stroke rate (1.1% vs 1.6%), death (0% vs 1.6%) and combined stroke/death adverse event rate (3.4% vs 4.1%).37
There are several limitations to our study: it is a nonrandomized, retrospective study, and patient inclusion, preoperative evaluation of the carotid lesion, and decisions during the intervention that might affect the outcome were all subject to each operator's discretion. This causes many biases typical for this type of study regardless of the careful data collection and analysis performed by the authors. Moreover, retrospective data collection has its own flaws as the same type and amount of information is not available for all patients and, therefore, some demographic, angiographic, procedural, and outcome data are missing for the final analysis. However, as CAS is a relatively new procedure and there are no randomized trials to answer questions regarding the impact of gender on carotid stenting, our study, being one of the largest of its kind, should provide useful information regarding carotid stenting in women.
In addition, our long-term data are derived from a relatively short follow-up period with an average duration of 15.6 months. Few of our patients have a shorter follow-up of only 3 months and thus the Kaplan-Meier curves are limited. However, it is known that restenosis due to intimal hyperplasia occurs within the first 12-18 months after the primary procedure and our analyses have shown no statistically significant difference in late occurring events or restenoses between the genders within this period. Future studies with longer follow-up are necessary to evaluate the long-term impact of the carotid stenting in the natural history of the disease in the different genders.
Conclusion
In conclusion, this study is one of the first and largest to address the issue of carotid angioplasty and stenting with regard to outcome by gender. We have found CAS to be safe, with similar angiographic characteristics between genders, and similar perioperative outcomes. Future randomized studies would be necessary to answer the question of how women and men may differently respond to vascular interventions in each of the vascular beds in which we intervene.
Author contributions
References
- Endarterectomy for asymptomatic carotid artery stenosis (Executive Committee for the Asymptomatic Carotid Atherosclerosis Study). JAMA. 1995;273:1421–1428
- [No authors listed.] Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis (North American Symptomatic Carotid Endarterectomy Trial Collaborators). N Engl J Med. 1991;325:445–453
- [No authors listed.] MRC European Carotid Surgery Trial: interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis (European Carotid Surgery Trialists' Collaborative Group). Lancet. 1991;337:1235–1243
- Efficacy of carotid endarterectomy for asymptomatic carotid stenosis (The Veterans Affairs Cooperative Study Group). N Engl J Med. 1993;328:221–227
- Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial. Lancet. 2004;363:1491–1502
- Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med. 2004;351:1493–1501
- 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
- Endarterectomy versus stenting in patients with symptomatic severe carotid stenosis. N Engl J Med. 2006;355:1660–1671
- [No authors listed.] Endovascular versus surgical treatment in patients with carotid stenosis in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS): a randomised trial. Lancet. 2001;357:1729–1737
- Analysis of pooled data from the randomised controlled trials of endarterectomy for symptomatic carotid stenosis. Lancet. 2003;361:107–116
- . Sex difference in the effect of time from symptoms to surgery on benefit from carotid endarterectomy for transient ischemic attack and nondisabling stroke. Stroke. 2004;35:2855–2861
- Long-term results of carotid stenting versus endarterectomy in high-risk patients. N Engl J Med. 2008;358:1572–1579
- Multifactorial index of cardiac risk in noncardiac surgical procedures. N Engl J Med. 1977;297:845–850
- . The role of anesthesia in surgical mortality. JAMA. 1961;178:261–266
- . Carotid artery duplex scanning. J Clin Ultrasound. 1987;15:635–644
- . Ultrasonic duplex scanning for disease of the carotid artery. Circulation. 1981;64:1191–1195
- Analysis of anatomic factors and age in patients undergoing carotid angioplasty and stenting. Ann Vasc Surg. 2005;19:798–804
- . Sex differences in carotid bifurcation anatomy and the distribution of atherosclerotic plaque. Stroke. 2001;32:1525–1531
- . Sex differences in carotid plaque and stenosis. Stroke. 2004;35:477–481
- . Geometry of the human common carotid artery (A vessel cast study of 86 specimens). Pathol Res Pract. 2002;198:543–551
- . Diameter and compliance in the human common carotid artery–variations with age and sex. Ultrasound Med Biol. 1995;21:1–9
- . Predicting the normal dimensions of the internal and external carotid arteries from the diameter of the common carotid. Eur J Vasc Surg. 1987;1:91–96
- Gender as a primary predictor of outcome after carotid endarterectomy. J Vasc Surg. 2002;35:748–753
- Carotid endarterectomy in women: challenging the results from ACAS and NASCET. Ann Surg. 2001;234:438–445discussion 45-6
- . Carotid endarterectomy in women versus men: patient characteristics and outcomes. J Vasc Surg. 1997;25:890–896discussion 7-8
- . Gender and carotid endarterectomy: does it matter?. J Vasc Surg. 2000;31:1103–1108discussion 8-9
- Carotid endarterectomy in female patients: are the concerns of the Asymptomatic Carotid Atherosclerosis Study valid?. J Vasc Surg. 2001;33:236–240discussion 40-1
- . Association of sex with perioperative mortality and morbidity after carotid endarterectomy for asymptomatic carotid stenosis. J Cardiothorac Vasc Anesth. 2003;17:10–16
- . Where next after SPACE and EVA-3S: ‘the good, the bad and the ugly!'. Eur J Vasc Endovasc Surg. 2007;33:44–47
- Immediate and late clinical outcomes of carotid artery stenting in patients with symptomatic and asymptomatic carotid artery stenosis: a 5-year prospective analysis. Circulation. 2001;103:532–537
- Carotid stenting done exclusively by vascular surgeons: first 175 cases. Ann Surg. 2005;242:431–436discussion 6-8
- . No gender influences on clinical outcomes or durability of repair following carotid angioplasty with stenting and carotid endarterectomy. Vasc Endovascular Surg. 2008;42:321–328
- . Clinical and technical factors influencing recurrent carotid stenosis and occlusion after endarterectomy. J Vasc Surg. 1987;5:702–706
- . Natural history of recurrent and residual stenosis after carotid endarterectomy: implications for postoperative surveillance and surgical management. Surgery. 1992;112:656–661discussion 62-3
- . Gender differences in blood velocities across carotid stenoses. J Vasc Surg. 2004;40:939–944
- . Gender differences in blood flow velocities after carotid angioplasty and stenting. Ann Vasc Surg. 2007;21:576–579
- Impact of diabetes, patient age, and gender on the 30-day incidence of stroke and death in patients undergoing carotid artery stenting with embolus protection: a post-hoc subanalysis of a prospective multicenter registry. J Endovasc Ther. 2007;14:271–278
Competition of interest: none.
PII: S0741-5214(08)01585-1
doi:10.1016/j.jvs.2008.08.110
© 2009 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
