Endovascular Management versus Surgery for Proximal Subclavian Artery Lesions

Article Outline

• Abstract
• Introduction
• Materials and Methods
  • Technique of sPTA
  • Technique of SCT
  • Antithrombotic Regimen
  • Postoperative Management and Follow-Up
  • Statistical Presentation and Reporting Standards
• Results
  • Patient Demographics and Indication for Treatment
  • Anatomy of Supra-Aortic Extracranial Artery Occlusive Lesions
  • Procedural Success Rate
  • Patency and Follow-Up
  • Postprocedural Complications
• Discussion
• Conclusions
• References
• Copyright

Current management of subclavian artery (SA) lesions is controversial. Subclavian-to-carotid artery transposition (SCT) may be challenging but exhibits unparalleled long-term results. Stent-supported percutaneous transluminal angioplasty (sPTA) is technically easier but not always feasible. Long-term results and comparisons have not been published. We compared both methods performed by vascular surgeons. Data were collected prospectively with retrospective analysis at a tertiary-care center. sPTA was performed through a retrograde transbrachial access using self-expanding nitinol stents. Open surgery was SCT only. Society for Vascular Surgery/International Society of Cardiovascular Surgery reporting standards were applied. Seventy-four patients underwent treatment from January 1995 to August 2007 (median age 62.6 years, 40 female; left-sided pathology 60 [81.1%]; risk factors: hypertension 45 [60.8%], dyslipidemia 47 [63.5%], diabetes 21 [28.4%], smoking 43 [58.1%], SA occlusion 50 [67.6%]). Forty patients (54.1%) underwent primary sPTA (62.5% occlusions) and 34 SCT (73.5% occlusions). The two groups were comparable with regard to risk factors. In 12 patients occlusions could not be recanalized (30%), and in two stents failed within 1 month (both for stenosis). All but one underwent subsequent uneventful SCT. All SCTs were successful. No risk factor could be identified for treatment failure except sPTA (p = 0.002, Fisher's exact test). Median follow-up was 50.1 months with sPTA and 52.6 months with SCT. No procedure failed during follow-up in either group. sPTA can be performed successfully by surgeons. Primary sPTA failed in 48% of occlusions (30% of all sPTAs). Prediction of failure is not possible. According to our experience, we recommend primary sPTA for SA stenosis and surgery for SA occlusions.

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Introduction 

Best management of first subclavian artery (SA) segment stenotic and occlusive pathologies remains controversial. Initially, symptomatic SA lesions characterized by vertebrobasilar insufficiency (VBI) and/or upper limb ischemia have been treated via direct repair. However, transthoracic procedures have demonstrated unfavorable morbidity and mortality rates.¹ Therefore, extrathoracic approaches and extra-anatomic procedures for the reconstruction of proximal SA lesions (i.e., subclavian-to-carotid transposition [SCT], carotid-subclavian artery bypass, subclavian-to-subclavian bypass, axilloaxillary bypass) have been developed and have enjoyed increasing popularity. According to the literature, SCT, described by Parrott in 1964, is the most durable procedure with reported long-term patency rates of 90-100%.², ³, ⁴, ⁵ Most recently, SCT has gained renewed importance in patients suffering from aneurysms of the proximal descending aorta, to create an adequate proximal landing zone for endovascular repair.⁶, ⁷ Nevertheless, for anatomical reasons, all procedures involving the SA are technically demanding, and local complications may play a detrimental role.⁸ Therefore, endovascular techniques (percutaneous transluminal angioplasty [PTA] with or without stenting) for the treatment of stenotic and occlusive SA lesions, first reported in 1980 by Bachmann and Kim,⁹ have become an increasingly popular treatment option. Larger trials comparing surgical and endovascular treatment of SA pathologies are limited. The aim of this study is a head-to-head analysis of SCT versus stent-supported PTA (sPTA) in patients with symptomatic proximal SA lesions.

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Materials and Methods 

Data were entered prospectively into a computerized vascular database and analyzed in a retrospective manner. From January 1995 to March 2007, 74 patients were treated for symptomatic SA pathologies by SCT or sPTA in a tertiary university-based care center. Both patient groups were treated by the same group of surgeons. Preferentially, an endovascular approach was chosen by the attending surgeon. Prior to the procedure, medical history was evaluated and physical examination with pulse wave analysis and noninvasive bilateral blood pressure measurement of the upper extremities was performed. Imaging modalities before surgery or endovascular treatment included color-coded duplex sonography (DS) and arteriography or magnetic resonance angiography (MRA) of the aortic arch vessels. Brain imaging was routinely performed using either computed tomography (CT) or magnetic resonance imaging (MRI). Additionally, all patients were seen by an independent neurologist before the procedure.

Technique of sPTA 

All endovascular procedures were performed in the endovascular operative suite under local anesthesia with the Seldinger technique. The transbrachial approach via the ipsilateral cubital artery was used in all patients, as described by Queral and Criado.¹⁰ After sonographically guided puncture of the artery, a guidewire was inserted and a 5-French introducer sheath placed. Systemic heparinization (25-100 U/kg) was administered after safe vascular access was established. After the guidewire and angiographic catheter were passed through the lesion, the introducer sheath was changed to 6 French. After angiography of the aortic arch vessels, the SA lesion was predilated with a balloon catheter, followed by deployment of a self-expanding nitinol stent and consecutive stent dilation to achieve an optimal stent shape in the curved SA. After final angiographic control and measurement of the trans-lesion pressure gradient, heparin was reversed for removal of the introducer sheath. Stenting was considered successful if the stent was in correct position and the pressure gradient across the lesion did not exceed 5-10 mm Hg or the residual stenosis was <30%. The puncture site was compressed manually for 15 min.

Technique of SCT 

The operation was performed under general anesthesia. The patient was placed supine with a roll positioned between the scapulae to elevate the shoulders. The neck was extended as much as possible with the head turned to the contralateral side. We preferred a medial approach to the central SA via a transverse supraclavicular incision 1-2 cm superior to the clavicle between the bellies of the sternocleidomastoid muscle. The technical details of procedure have been described extensively by our group.⁸

Antithrombotic Regimen 

Antithrombotic therapy was started prior to the procedure and included aspirin 100 mg/day orally plus weight-adjusted low-molecular weight heparin subcutaneously for both patient groups. At discharge low-molecular weight heparin was stopped and aspirin was continued indefinitely.

Postoperative Management and Follow-Up 

All patients underwent independent postprocedural neurological examination for the detection of central neurological deficits. In surgical cases laryngoscopy was routinely performed for the detection of recurrent laryngeal nerve injuries. sPTA patients underwent color-coded DS after the procedure. Fluoroscopy was undertaken in all open surgical cases to rule out phrenic nerve palsies. In cases of left-sided SCT, patients received a fatty meal on postoperative day 3 to identify lymphatic leakage before drain removal. After discharge, all patients were seen every 3 months during the first year and annually thereafter. Follow-up visits were carried out by an attending vascular surgeon. Routine management included medical history and physical examination with pulse wave analysis and noninvasive bilateral blood pressure measurement of the upper extremities. Color-coded DS was performed annually and additionally when a blood pressure difference >15 mm Hg was present. MRA and CT angiography (CTA) were performed only if there was suspicion of significant restenosis of the SA or the need of a new procedure for the supra-aortic branches, especially the carotid arteries.

Statistical Presentation and Reporting Standards 

Society for Vascular Surgery/International Society of Cardiovascular Surgery reporting standards were used for preparation of this report.¹¹ Data were analyzed using the two-sided, independent Student's t-test, Pearson's chi-squared test, and Fisher's two-sided exact test. Kaplan-Meier product limit estimator and life-table analyses together with standard errors of cumulative patency were applied in both study groups. Kaplan-Meier curves of both patient groups were compared and tested using the log-rank test, Gehan's Wilcoxon test, and the Cox-Mantel test. p < 5% was considered statistically significant. All analyses and illustrations were done using Statistica 6.1 (StatSoft, Tulsa, OK).

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Results 

From January 1995 through August 2007, 74 patients (40 females, mean age 61 years, range 39-85 years) underwent sPTA (n = 40) or primary SCT (n = 34) for symptomatic proximal SA occlusive lesions (occlusion or hemodynamic significant stenosis [>70%]). SA occlusive disease (SAOD) was of atherosclerotic origin in all cases.

Patient Demographics and Indication for Treatment 

Forty patients (21 females, mean age 61 years, range 44-79 years) underwent primary sPTA. Thirty-four patients (19 females, mean age 60 years, range 39-85 years) underwent primary SCT for SAOD. There was no statistically significant difference between sPTA patients and primary SCT patients concerning gender, age, and cardiovascular risk factors (Table I). Symptoms of SAOD were also equally distributed in the patient groups (Table II). The most common indications for sPTA and SCT were signs of VBI such as vertigo (n = 29, 40%), and vertigo with arm claudication (n = 18, 24%). Other clinical complaints, including arm claudication (n = 14, 19%), were encountered infrequently. There was no statistical significance in the preoperative presentation in both groups.

Table I. Demographic details of the 74 patients undergoing either sPTA or primary SCT

SD, standard deviation.

Table II. Clinical symptoms as indication for treatment of the 74 patients undergoing either sPTA or SCT

Anatomy of Supra-Aortic Extracranial Artery Occlusive Lesions 

There were more SA occlusions than SA stenoses (n = 50, 67% vs. n = 24, 33%). In addition, other supra-aortic trunk lesions were observed frequently in both groups (Table III). There was no statistical difference between the treatment groups regarding SA pathology or other supra-aortic artery pathologies. In three patients carotid thrombendarterectomy was performed at least 4 weeks prior to SCT for asymptomatic carotid disease. No carotid interventions were performed before sPTA.

Table III. Description of supra-aortic arterial occlusive lesions in the 74 patients undergoing either sPTA or primary SCT (stenosis defined as >30% lumen reduction)

	sPTA	Primary SCT	p
SA
SA occlusion	25 (63%)	25 (74%)	0.33
SA stenosis	15 (38%)	9 (27%)	0.33
ICA
Ipsilateral ICA stenosis	4 (10%)	4 (12%)	-
Contralateral ICA stenosis	3 (8%)	3 (9%)	-
Bilateral ICA stenosis	10 (25%)	4 (12%)	-
Total ICA	17 (43%)	11 (33%)	0.55
VA
Ipsilateral VA stenosis	2 (2%)	4 (12%)	-
Contralateral VA stenosis	0 (0%)	0 (0%)	-
Bilateral VA stenosis	1 (2.5%)	0 (0%)	-
Total VA	3 (4.5%)	4 (12%)	0.38

SA, subclavian artery; ICA, internal carotid artery; VA, vertebral artery.

Procedural Success Rate 

No SCT procedure failed. In 12 patients (30%) sPTA primarily failed because the guidewire could not be passed through the SA lesion. The procedural success rate for all endovascular procedures was 70% (28 out of 40). All of the primary unsuccessful procedures presented with SA occlusion. The procedural success rate for SA occlusions was 52% (13 out of 25). The primary success rate for SA stenosis was 100%. In two of the patients early stent occlusion occurred on days 7 and 27 after the intervention, respectively. Both stent failures occurred after treatment of SA stenosis. One patient received secondary SCT; the other denied any further treatment. All primary unsuccessful cases (occlusions) went on to secondary SCT.

Patency and Follow-Up 

All SCT procedures remained patent throughout follow-up. No restenosis was detected at the anastomotic site or in the SA distal to the anastomosis. No patient required secondary intervention of the central common carotid artery in this group. There were no reinterventions necessary at the stented segment of the SA or distal thereof after successful sPTA throughout follow-up. There was no statistically significant difference in patency rates between sPTA and all SCT patients (p = 0.14) (Fig. 1).

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• Fig. 1 

  Kaplan-Meier estimation of cumulative patency in the 73 patients undergoing either SCT or technically successful sPTA over 10 years of follow-up (one patient refused additional surgery after failed sPTA). The difference between the two groups is not significant (p = 0.14).

Postprocedural Complications 

No patient in either group presented with a postprocedural central neurological complication. In two primary SCT patients hematoma evacuation was necessary. In both cases there was no anastomotic leakage. In addition, two primary SCT patients developed transient cranial nerve palsy, resolving 4 and 6 weeks postoperatively (one recurrent laryngeal nerve palsy, one Horner syndrome). In one patient with secondary SCT, postoperative lymphatic leakage was observed, requiring surgical revision. In two sPTA patients vascular access complications requiring surgical revision were observed. One patient presented with incomplete arm ischemia due to brachial artery thrombosis after compression. In another patient a brachial artery pseudoaneurysm developed. Both patients were treated with local revision and vein patch angioplasty. The only factor for a primary procedural success rate was the use of SCT for the treatment of the SA pathology (p = 0.002) (Table IV).

Table IV. Postprocedural complications in the 74 patients undergoing either sPTA or primary SCT

BA, brachial artery.

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Discussion 

In our study we have compared two concurrently used methods to treat symptomatic central SAOD. Symptomatic SAOD is a rare entity compared to internal carotid artery stenosis. Sterpetti et al.¹² reported that SA revascularization represents only 4.6% of cases compared to the number of carotid endarterectomies. Whereas SCT has been performed since the 1960s, endovascular treatment of SAOD was first described in the 1980s.², ⁹ There is an ongoing debate as to whether stent implantation into the SA is superior to PTA alone.¹⁰, ¹³ Prospective randomized trials comparing different treatment modalities of SAOD and long-term results of endovascular management have not been published. Farina et al.¹⁴ compared PTA without stenting to carotid-to-subclavian bypass procedures in patients with proximal SAOD. The authors reported a patency rate of 54% in 21 PTA patients and a significantly better patency rate of 87% in 15 bypass patients after 3 years. In a recent report AbuRahma et al.¹⁵ compared sPTA to carotid-to-subclavian bypass grafts. Although the bypass group was inhomogeneous, results were significantly better than those of sPTA. On the other hand, it is well known that the results of bypass are inferior to those of SCT.³ Our study represents the first comparison of sPTA versus SCT in patients suffering from symptomatic proximal SAOD.

In this study the two patient populations were well matched with regard to risk factors of vascular disease, as well as anatomy and supra-aortic trunk pathology. This is important as there is a propensity toward endovascular management in patients with stenotic SA lesions. In addition, right-sided lesions are rather treated with surgery because of the higher incidence of central neurological events during endovascular manipulation in this group.¹⁶

In our study population the 5-year patency rate of successful sPTA was 95%. Patency rates of 80-100% have been reported for balloon angioplasty alone for SA stenosis, whereas patency rates for PTA of SA occlusion are reported in the range of 20-50%.¹⁷, ¹⁸ With the implementation of sPTA by Queral and Criado,¹⁰ patency rates in patients with SA occlusion increased to 70-100%.¹⁹ In 1999, Rodriguez-Lopez et al.¹⁹ reported a 73% overall primary patency and a 90% overall secondary patency rate in 69 patients with symptomatic SAOD undergoing primary SA stenting. The authors compared their results with the outcome of surgery for symptomatic SAOD in the literature. They reported no significant difference in patency rates between stenting and surgery, although SCT was not included in their review.¹⁹ De Vries et al.¹⁶ in 2005 reported a primary patency for PTA with or without stenting at 5 years of 89%. Nakamura et al.²⁰ published a 5-year patency rate of 99% in 320 patients undergoing sPTA for symptomatic SAOD. This multicenter study is still under way. Whereas PTA with on-demand stent placement of SAOD is usually recommended in cases of SA occlusion, SA dissection, and significant residual stenosis after PTA, some authors recommend primary stenting (as we did) to achieve improved patency rates and to prevent redo procedures.¹⁹, ²¹ At present, there is still an ongoing debate as to whether the use of primary stent or PTA alone yields superior long-term results in patients with proximal SAOD.¹³ In contrast to most series, we have used self-expanding nitinol stents because we believe that flexibility in this region is more important than radial force. There was a 48% incidence of primary sPTA failure in SA occlusions, which cannot be attributed to the use of a stent, and only a small percentage of secondary failures of sPTA in stenoses.

All SCT procedures were found to be patent after a mean follow-up time of 52 months. Reported patency rates for surgically reconstructed SAOD vary from 80% to 100%.³, ⁴, ⁵ Cina et al.²² in 2002 described the outcome of a cohort of patients undergoing SCT for SAOD and performed a systematic review of the literature on SCT and carotid-SA bypass. Patency and freedom from clinical symptoms were higher with SCT than with carotid-SA bypass (98% vs. 84%, p < 0.0001). These results are in accordance with results from other studies, which reported 100% long-term patency rates of SCT in patients suffering from proximal SAOD.³, ⁴, ⁵, ⁸

Some authors recommend dual antiplatelet therapy after sPTA of SAOD to minimize stent occlusion rates.²³ Our patients received single oral antithrombotic therapy (aspirin 100 mg/day) in both treatment options, resulting in two stent occlusions after days 7 and 27, respectively. Prospective randomized trials are needed to evaluate the best antithrombotic management (single versus dual antiplatelet treatment) after endovascular revascularization of SAOD.

In the current literature, the primary technical success rate of endovascular recanalization of proximal SAOD ranges 70-100%.²³ In our study, in 12 out of 40 primary PTA patients (30%) the occluded SA lesion could not be passed with the guidewire, although we preferred the retrograde transbrachial approach.²³ These patients underwent subsequent SCT successfully without perioperative complications. This is a remarkable finding as one would expect increased difficulty of dissection after endovascular manipulation in the friable central portion of the SA. A primary failure rate of 30% seems to be high but reflects the experience of open surgery in this region by our group. If passage of the guidewire cannot be achieved safely, conversion to SCT has been felt to be the better option for the patient. In that regard it may be arguable whether SA occlusions should be treated by SCT primarily. Our complication rate of primary SCT was 11.8%. Postoperative complications after SCT are observed in 10-15% and include mostly reversible local complications such as hematomas, nerve palsies, and lesion of the lymphatic duct.⁵, ²², ²⁴ Cina et al.²² reported in their systematic review cranial nerve injuries in 11.2% of patients undergoing SCT and in 9.2% in patients undergoing bypass grafting. The incidence of nerve palsies and thoracic duct injuries can be reduced significantly using a medial approach to SCT.⁸ The medial approach was used preferentially among patients undergoing surgery in this study.⁸

In the sPTA group we observed complications in 10%. De Vries et al.¹⁶ reported a local complication rate of 4.5% and a combined stroke and death rate of 3.6% in patients undergoing PTA of proximal SAOD. The authors argued that especially right-sided SA lesions carry the risk of distal embolization during endovascular manipulation due to the proximity of the common carotid artery. We observed no major neurological events in our sPTA group. All complications were local (one pseudoaneurysm and one thrombosis of the brachial artery) with consecutive surgical redo repair and occurred in 5% of our patients. Although the femoral approach to sPTA is used frequently, we prefer the transbrachial approach because of the shorter distance from the puncture site to the lesion and the easier maneuverability of the guidewire. Local complications at the puncture site may be further reduced by a surgical cutdown and open puncture of the brachial artery.

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Conclusions 

In conclusion, sPTA of symptomatic SAOD can be performed successfully by vascular surgeons. Long-term results are excellent when the sPTA is not enforced and performed only in straightforward cases. According to our experience, we recommend primary sPTA for SA stenosis and surgery for SA occlusions. sPTA for occlusions may be attempted, but one must encounter a 50% failure rate. Our results should be confirmed with a prospective randomized trial.

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