Neuroradiology

, Volume 56, Issue 6, pp 467–476 | Cite as

Complications of mechanical thrombectomy for acute ischemic stroke—a retrospective single-center study of 176 consecutive cases

  • Daniel Behme
  • Ludger Gondecki
  • Sarah Fiethen
  • Annika Kowoll
  • Anastasios Mpotsaris
  • Werner Weber
Interventional Neuroradiology

Abstract

Introduction

There is only very limited data about complications in mechanical thrombectomy for acute ischemic stroke. The purpose of this study was to evaluate the frequency and the clinical relevance of procedure-related complications in mechanical thrombectomy.

Methods

We conducted a retrospective analysis of 176 consecutive acute ischemic stroke cases that were treated with mechanical thrombectomy. Primary outcome measures included the following: symptomatic intracranial hemorrhage (sICH), vessel dissection, emboli to new vascular territories, vasospasm, and stent dislocation/occlusion whenever appropriate. Secondary outcome measures included mTICI score, time from symptom onset to revascularization, and time from groin puncture to revascularization as well as the early clinical outcome at discharge.

Results

Complications occurred in 20/176 patients (11 %) comprising 23 adverse events at the following rates: sICH 8/176 (5 %), emboli to new vascular territories 4/176 (2 %); vessel dissection 3/176 (2 %); vasospasm of the access vessel 5/176 (3 %); stent dislocation in 1/42 (2 %); and stent occlusion in 2/42 (5 %). Two out of 20 (10 %) suffered from two or more procedure-related complications. There was a statistically significant correlation of complications with time from groin puncture to revascularization, unfavorable revascularization results, and unfavorable clinical outcome.

Conclusion

Overall, the frequency of procedure-related complications lies within acceptable limits for an emergency procedure. The endovascular treatment does not seem to add significantly to the stroke patients’ risk of sICH but implies an innate risk of stroke in an initially uninvolved territory. Furthermore, a prolonged endovascular procedure beyond an hour is correlated with higher complication rates, which underlines the importance of a swift and complete revascularization.

Keywords

Complications Thrombectomy Acute ischemic stroke Stenting 

Abbreviations

ENT

Embolization(s) to new territory

i.v.

Intravenous

IVT

Intravenous thrombolysis

MT

Mechanical thrombectomy

NIHSS

National Institute of Health Stroke Scale

mTICI

Modified thrombolysis in cerebral infarction

mRS

Modified Rankin Scale

n.s.

Not stated

ns

Not significant

SAH

Subarachnoid hemorrhage

sICH

Symptomatic intracranial hemorrhage

Introduction

Intravenous thrombolysis (IVT) improves clinical outcome after acute ischemic stroke [1, 2, 3]. The overall IVT revascularization rate was reported to reach 46.2 % [4]. Interestingly, the reported revascularization rates for IVT drop to 32–35 % in cases with proven proximal middle cerebral artery (MCA) occlusion and the success rate of IVT reaches a nadir in case of an underlying carotid T occlusion with about 6 % [5, 6, 7]. These limitations have led to an evolution of endovascular therapy, which has become an important option in the therapy of acute ischemic stroke [8, 9, 10]. Over the last few years, several devices with the ability to directly disrupt and/or extract the clot in cases of a large, intracranial artery occlusion have been developed and studied in clinical practice [11, 12, 13, 14]. Recent studies showed promising results when a modern stent retriever device like the Solitaire FR (Covidien, Mansfield, MA, USA) or the TREVO (Concentric Medical, Fremont, CA, USA) was utilized for acute ischemic stroke treatment. Successful recanalization was reached in 92 to 94 % (self-reported success rate) of cases respectively [11, 12]. In analogy to IVT, the use of this devices goes along with the risk of intracranial hemorrhage, but also carries the risks of procedure-related complications such as embolization(s) to new territory (ENT), vessel dissection, and vasospasm [11, 15]. An analysis of the Solitaire flow restoration device versus the Merci Retriever in patients with acute ischaemic stroke (SWIFT) study data investigating complications of mechanical thrombectomy (MT) using Solitaire FR and the Merci (Concentric Medical) retriever has been published recently and could not find any significant correlation of complications with age, time of symptoms, or the type of stent retriever [16]. TREVO 2 investigators observed a tenfold higher vessel perforation rate in the Merci group [12]. Regarding other procedural severe adverse events like symptomatic intracranial hemorrhage (sICH), vessel dissection or perforation, ENT and major groin puncture complications, the TREVO 2 study could not show significant differences between the Merci and the TREVO device [12]. Additionally, two other studies recently compared MT with IVT versus IVT alone and could not demonstrate significant differences in these groups concerning clinical outcome and major complications [17, 18]. Other large studies like the STAR trial reported complication rates to be as low as about 7 % for the Solitaire FR [15]. The rates of sICH in cases of MT in combination with a preceding acute extracranial occlusion (tandem occlusion) are ambivalent, ranging from 7.3 to 9.7 %, respectively. Obviously, there is currently not enough data available for this subgroup [19, 20]. None of these studies have focused on procedural complications as primary endpoint. Alas, several published studies reported complication data incompletely and inconsistently (Table 1, systematic review) [14, 15, 16, 19, 21, 22]. The abovementioned studies are based on the concept of proximal aspiration via a balloon guide catheter in the terminus of the internal carotid artery (ICA). The rate of reported ENT varies between 0 and 7 % [11, 12, 15, 23]. The alternative concept of lesional aspiration based on a triaxial approach with an intermediate catheter for aspiration, e.g., the DAC (Concentric Medical) or the Penumbra 054/MAX (Penumbra Inc., Alameda, CA, USA), that is placed distally, as close to the clot as possible, has not yet been sufficiently evaluated. There is only a single pilot study available comprising 20 patients, where no ENT were reported [13]. Until today, there are no studies available comparing the large range of different modern MT devices, neither regarding the revascularization result, nor regarding complications. To our knowledge, this is the first study covering a representative range of devices as well as both concepts of aspiration as a primary endpoint.
Table 1

An overview of the systematic review on procedural complications in MT

Major procedural complication/Study

Complications of Endovascular Treatment for Acute Stroke in the SWIFT Trial with Solitaire and Merci Devices [16]

North American Solitaire Stent Retriever Acute

Stroke registry [14]:

Prospective, Multicenter, Single-Arm Study of Mechanical

Thrombectomy Using Solitaire Flow Restoration in Acute Ischemic Stroke [15]

Solitaire Flow Restoration thrombectomy for acute ischemic stroke: retrospective multicenter analysis of early post market experience after FDA approval [31]

Predictive factors of outcome and hemorrhage after acute ischemic stroke treated by mechanical thrombectomy with a stent retriever [32]

Retrospective multicenter study of Solitaire FR for revascularization in the treatment of acute ischemic stroke [21]

Endovascular treatment of acute intracerebral artery occlusions with the solitaire stent: single-center experience with 108 recanalization procedures [23]

Solitaire FR thrombectomy system: immediate results in 56 consecutive acute ischemic stroke patients [22]

Number of cases

n = 89

n = 354

n = 202

n = 101

n = 59

n = 124

n = 108

n = 56

sICH

1/89 (1.1 %)a

35/352 (9 %)a

3/202 (1.5 %)a

15/101 (15 %)a

5/59 (8.5 %)a

5/124 (4 %)a

2/108 (1.9 %)b

1/56 (1.8 %)a

Emboli to new vascular Territory

0/89 (0 %)

n.s.

2/202 (1 %)

n.s.

n.s

n.s.

4/108 (3.7 %)

n.s.

Vessel dissection

4/89 (4.5 %)

n.s.

2/202 (1.5 %)

n.s.

n.s

2 (1.6 %)

n.s.

n.s

aAccording to ECASS Criteria [2, 3]

bAfter vessel perforation with rescue device

Material and methods

Characteristics of the patients

We screened our prospectively kept neuro-interventional database on an intention-to-treat basis for all consecutive patients who underwent MT or MT plus emergency stenting between October 2009 and December 2012. To ensure comparability with other trials, we excluded patients from further analysis according to the following criteria: age >85; vessel occlusion in the anterior and posterior circulation at the same time; concomitant stenting of an intracranial vessel other than the V4-segment of the vertebral artery (VA) or the extracranial ICA.

Clinical assessment

A specialist neurologist assessed National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores on admission and discharge. A good early clinical outcome was defined according to the SWIFT study criteria as mRS ≤ 2 at discharge or NIHSS improvement of ≥10 points (compared to the pre-thrombectomy NIHSS).

Imaging evaluation

A senior neuroradiologist (AM) who was blinded to all clinical and outcome data evaluated all CT, CT angiography (CTA), and digital subtraction angiography (DSA) images. The images were screened for the following complications: sICH according to the European Cooperative Acute Stroke Study (ECASS)-III-definition [3], ENT, vessel dissection, vasospasm of the access vessel, as well as stent dislocation and stent occlusion within 24 h of the intervention. Hyperdensities on the postinterventional control CT scan were categorized based on the ECASS criteria [2]. We defined sICH to be procedure related when no IVT was carried out and the INR as well as the platelet count were normal. Furthermore, we defined isolated subarachnoid hemorrhage (SAH), ENT, vessel dissection, and stent dislocation/occlusion to be solely procedure related. Revascularization was measured using the modified thrombolysis in cerebral infarction (mTICI) score as recommended by the Cerebral Angiographic Revascularization Grading (CARG) Collaborators, defined as follows: grade 0: no perfusion; grade 1: antegrade reperfusion past the initial occlusion, but limited distal branch filling with little or slow distal reperfusion; grade 2a: antegrade reperfusion of less than half of the occluded target artery’s previously ischemic territory (e.g., in one major division of the MCA and its territory); grade 2b: antegrade reperfusion of more than half of the previously occluded target artery’s ischemic territory (e.g., in two major divisions of the MCA and their territories); and grade 3: complete antegrade reperfusion of the previously occluded target artery’s ischemic territory, with absence of visualized occlusion in all distal branches [24].

Procedures

All patients who presented within 8 h (anterior circulation stroke) or 12 h (posterior circulation stroke) after symptom onset with severe stroke symptoms underwent plain CT scan and CTA. CT perfusion was technically not available at the study period. All patients who were eligible for IVT according to the guidelines of the German neurologists association (DGN) received IVT independently. In case of a large artery occlusion on the CTA, patients were immediately transferred to the angiography suite.

Endovascular treatment

General approach

All treatments were performed under general anesthesia.

Biaxial approach, proximal aspiration

A 6 F guiding catheter, e.g., a Neuropath (Micrus, San Jose, CA) or a Neuron (Penumbra Inc.), was placed in the proximal portion of the access vessel. A heparinized saline solution was continuously applied through the catheter for the duration of the intervention. A 0.014-in. guide wire was advanced over a Rapidtransit microcatheter (Cordis, Bridgewater, NJ) and navigated distal to the clot. The microcatheter was then subsequently advanced over the wire through the clot. The correct position of the microcatheter’s tip distally of the clot and the selected vessel’s diameter were depicted by a gentle contrast injection before advancing the respective stent retriever through the microcatheter. The stent retriever was deployed with its distal portion being placed a few millimeters distal to the clot. At this point, a routine control injection was performed via the guide catheter to check for a potential restoration of flow distal to the thrombus. The stent retriever was kept deployed for 1 to 2 min and then gently withdrawn through the guide catheter under continuous proximal aspiration with a syringe. A control angiography was performed to assess the degree of recanalization and reperfusion. If there was no or incomplete recanalization, the procedure was repeated.

Triaxial approach with distal (lesional) aspiration

The procedure was performed analogous, but with the addition of an appropriately sized guiding catheter (Penumbra Neuron MAX 088) and an intermediate catheter (Penumbra 054 or 5MAX) for distal or lesional aspiration as close to the clot as technically possible.

Tandem occlusions

In case of a tandem occlusion, we used the so-called antegrade approach (stenting followed by thrombectomy) in all cases. An 8 F Brite Tip guiding catheter (Cordis) or a Neuron MAX 088 was placed into the ipsilateral distal common carotid artery. A 0.014-in. wire was then passed through the proximal ICA occlusion, and a microcatheter was advanced over this wire into the petrous portion. Then a contrast injection was performed in order to verify passage into the true lumen and to depict the extent of the occlusive lesion. Extracranial carotid stenting was carried out without the use of any protective devices, as there was an intracranial obstruction in all cases. Pre-stenting balloon angioplasty was performed when necessary with a 3.0- or 3.5-mm monorail balloon. All patients received a Wallstent (Boston Scientific, Natick, MA). For post-stenting angioplasty, 4.5- or 5.0-mm monorail balloons were utilized. The subsequent thrombectomy in the intracranial portions was carried out in a usual manner. In case of a biaxial approach, the Wallstent was passed with the guiding catheter first in order to withdraw the stent retriever into the guide without interfering with the Wallstent. In case of a triaxial approach, the stent retriever was withdrawn into the intermediate aspiration catheter, without the danger of interfering with the Wallstent.

Periprocedural antiplatelet regimen in tandem occlusions

If the patients had no prior medication with dual antiplatelet therapy for other medical indications at the time of treatment, eptifibatide was continuously infused for 24 h to prevent secondary stent occlusion. We decided for eptifibatide in contrast to acetylsalicylic acid as early antiplatelet therapy because of its short half-life allowing for decompressive craniectomy in case of edematous brain swelling. The combination of IVT and eptifibatide has been considered safe [25]. Patients were monitored in the intensive care unit postinterventionally. A control CT scan was obtained after 24 h or earlier in case of any neurological worsening (NIHSS score deterioration of >4). After intracranial hemorrhage and decompressive craniectomy were ruled out, the regimen was switched to a secondary prophylaxis of stent occlusion based on a dual antiplatelet therapy: under continuous i.v. eptifibatide patients received a loading dose of 300 mg clopidogrel and 500 mg acetylsalicylic acid (ASA). Patients with daily ASA medication prior to treatment did not receive an ASA loading dose. The administration of eptifibatide was stopped 4 h after loading with clopidogrel (and ASA whenever applicable). Patients continued with lifelong ASA (100 mg/day) and additional clopidogrel (75 mg/day) for 8 weeks. If a Multiplate® testing 72 h after loading resulted in an insufficient efficacy of clopidogrel (nonresponder), we decided for prasugrel (10 mg/day) for the duration of 8 weeks.

Statistical analysis

Standard summary statistics were calculated for all study variables as appropriate to the type of data collected (e.g., continuous versus categorical versus ordinal). No formal hypothesis testing of overall study endpoints was prespecified. Nevertheless subgroups of interest were identified a priori and statistical comparisons between these cohorts were performed using contingency tables and Fisher’s exact test. Statistical analyses were carried out in Graph pad prism 6.01 (Graph pad software Inc., La Jolla, CA, USA). A p value of ≤0.05 was considered to be statistically significant.

Results

A total of 195 patients with acute ischemic stroke were treated by endovascular means between October 2009 and December 2012 at our center. To ensure comparability to other published studies, 19 patients were excluded from further analysis. Four (21 %) of the excluded patients suffered from a procedural complication; no sICH occurred in this group (Supplementary data, Tables 2 and 3). A total of 176 patients underwent further analysis. Demographics were (Table 2) as follows: median age, 70.5 (25–85); male sex, 52 %. For endovascular therapy, 76/176 (43 %) of patients were referred. Sites of occlusion were carotid T 60/176 (34 %), MCA M1 66/176 (38 %), MCA M2 18/176 (10 %), and BA 32/176 (18 %). IVT was carried out in 134/176 (76 %) of cases. Median NIHSS on admission was 16 (6–35), Median baseline mRS was 5 (3–5). Median time from symptom onset to admission was 1:55 h (0.14–10:13 h) for those patients who were directly admitted to our center and 2:48 h (0:51–9:28 h) for those patients who were secondarily referred.
Table 2

Demographics

 

All cases (n = 176)

Age (years)

 Median

 Median time symptom mean

70.5 (25–85)

67.1 (±12.62)

 Male sex

51.7 %

 Referred to our center for endovascular treatment

76 (43 %)

 Median time symptom onset to admission

 Median time symptom onset to admission (referred patients)

1:55 (0:14–10:13)

2:48 (0:51–9:28)

NIHSS score

 Median

 Mean

16 (6–35)

16.9 (±5.65)

mRS

 Median

5 (3–5)

 t-PA-failure

134/176 (76 %)

 Blood sugar glucose (mg/dl)

113 (53–301)

 INR

1.04 (0.88–2.79)

Occlusion site

 Carotid T

 MCA M1

 MCA M2

 BA

 Preceding ICA occlusion

 Preceding VA occlusion

 Preceding ICA dissection

60 (34 %)

66 (38 %)

18 (10 %)

32 (18 %)

32 (18 %)

6 (3 %)

4 (2 %)

Suspected stroke cause

 Cardioembolic

 Thromboembolic

 Unknown/other

80 (46 %)

60 (34 %)

36 (20 %)

Complications

Complications and correlation with clinical aspects

Complications occurred 23 times in 20/176 patients (11 %) (Table 3). Eight patients suffered from a sICH. Patterns of sICH were as follows: isolated SAH (1/8), parenchymal hematoma type 1 (PH1) + SAH (1/8), parenchymal hematoma type 2 (PH2) + intraventricular hematoma (IVH) (3/8) and PH2 with IVH and SAH (3/8). (All hyperdensities found in control CT scans are listed in Table 4, Supplementary data). One of these patients died within 24 h after the intervention, four within the time of hospitalization after stroke. Six out of eight patients who suffered from a sICH had received IVT; one was not eligible for IVT as the platelet count was too low (47,000/μl). According to our definition, two patients suffered from a procedure-related sICH whereby one of them suffered from a symptomatic isolated SAH. No vessel perforation was seen in any case suffering from a sICH after MT. Subarachnoid hyperdensities were found in the control CT scans of 11 patients. Except for one patient who died after an isolated SAH and those cases with SAH additionally to intraparenchymal bleeding, all cases of isolated subarachnoid hyperdensities were asymptomatic. Three patients who showed an asymptomatic, isolated subarachnoid hyperdensity did receive IVT. ENT occurred in three patients, in one patient two times. In three of these four cases, the embolization affected the anterior cerebral artery (ACA) territory after MT of an occluded M1-segment of the MCA. In one case, embolization of the PCA territory was found after MT of an occluded M1-segment and was based on a PCA of embryonic origin. Two of these three patients died within the acute phase after stroke; the remainder did not show a clinical improvement after MT. Vessel dissection occurred in three cases; dissection of the distal ICA in two and dissection of the V3-segment of the VA in one case, respectively. Both cases of ICA dissections were asymptomatic, the patient who suffered from a VA dissection died within 24 h after intervention because the BA occlusion could not be recanalized and the patient suffered from a brain stem infarction. Vasospasm of the access vessel occurred in five cases and could be treated successfully with intra-arterial nimodipine in all cases; no MT had to be cancelled and none of these events was clinically relevant. There was no statistically significant correlation of complications with age (≤70 vs. >70, p = 1.0), IVT vs. no IVT (p = 0.2), baseline NIHSS (≤16, >16, p = 0.66) or with referral for endovascular therapy vs. primary admission to our center (p = 1.0). There was a highly significant correlation of complications with unfavorable clinical outcome (p = 0.0054) (Table 4).
Table 3

Overview of all complications

Complication

n (%)

All

23

sICH (any)

PH1+ SAH

PH2+ IVH

PH2+ IVH + SAH

Symptomatic isolated SAH

Procedure relateda

8 (5 %)

1 (0.6 %)

3 (2 %)

3 (2 %)

1 (0.6 %)

2 (1 %)

Emboli to new vascular territories

4 (2 %)

Vessel dissection

3 (2 %)

Vasospasm of the access vessel

5 (3 %)

Stent dislocation

1 (2 %)b

Stent occlusion

2 (5 %)b

aNo IVT, normal coagulation parameters in one case and one isolated SAH

bOf those patients who received an additional stenting

Table 4

Association of procedural complications with clinical aspects

Clinical aspects

+, n (%)

−, n (%)

p value

Age

 ≤70

 >70

12/89 (13.5 %)

11/87 (12.6 %)

77/89 (87 %)

76/87 (87 %)

1 (ns)

Concomitant IVT

 t-PA

 no t-PA

15/134 (11.2 %)

8/42 (19 %)

119/134 (89 %)

34/42 (81 %)

0.20 (ns)

NIHSS

 ≤16

 >16

9/77 (11.7 %)

14/98 (14.3 %)

68/77 (88 %)

84/98 (86 %)

0.66 (ns)

Initial presentation

 Directly admitted to our center

 Referred

13/100 (13 %)

10/76 (13.2 %)

87/100 (87 %)

66/76 (87 %)

1 (ns)

Clinical outcome

 Good clinical outcome

 Unfavorable clinical outcome

3/70 (4.3 %)

20/106 (18.9 %)

67/70 (96 %)

86/106 (81 %)

0.0054**

Correlation of complications with technical aspects

Overall, a successful recanalization (mTICI ≥ 2b) was reached in 135/176 (77 %) of cases. Median time from symptom onset to substantial revascularization was 4:18 h (1:19–13:25 h) and median time from symptom onset to end of angiography for those patients with unfavorable revascularization result was 4:33 h (2:07–9:11 h). Median time from groin puncture to substantial revascularization was 1 h (0:14–3:23 h) and median time from groin puncture to end of angiography with unfavorable result was 1:23 h (0:17–2:49 h) (Table 1, Supplementary). There was no statistically significant correlation with time from symptom onset to substantial or unfavorable revascularization (p = 0.58/p = 0.067). However, with a prolonged time from groin puncture to substantial or unfavorable revascularization of 1 h or longer, there was a statistically significant correlation (p = 0.042/p = 0.039). Additionally, we observed a significant correlation of an unfavorable revascularization result with complications (p = 0.031) (Table 5). A subgroup analysis was performed for the two largest groups who were treated by means of the Solitaire FR or the Penumbra 3D Separator together with a lesional aspiration device such as the Penumbra aspiration catheter 054. Regarding these subgroups, we could not observe any statistically relevant difference between these devices (p = 0.78) (Table 6).
Table 5

Association of procedural complications with distinct technical aspects

Technical aspect

+, n (%)

−, n (%)

p value*

Time symptom onset to substantial revascularization

 mTICI 2b or higher

  

0.58 (ns)

 ≤4:30 h

 >4:30 h

6/72 (8 %)

7/62 (11 %)

66/72 (92 %)

55/62 (89 %)

Time symptom onset to end of angiography

 mTICI 2a or less

  

0.067 (ns)

 ≤4:30 h

 >4:30 h

2/20 (10 %)

8/21 (38 %)

18/20 (90 %)

13/21 (62 %)

Time symptom onset to substantial revascularization

 mTICI 2b or higher (referred)

  

0.70 (ns)

 ≤4:30 h

 >4:30 h

2/22 (9 %)

5/36 (14 %)

20/22 (91 %)

31/36 (86 %)

Time symptom onset to end of angiography

 mTICI 2a or less (referred)

  

0.11 (ns)

 ≤4:30 h

 >4:30 h

2/4 (50 %)

1/14 (7 %)

2/4 (50 %)

13/14 (93 %)

Time from groin puncture to substantial revascularization

 mTICI 2b or higher

  

0.042*

 ≤1:00 h

 >1:00 h

3/69 (4 %)

10/66 (15 %)

66/69 (96 %)

56/66 (85 %)

Time from groin puncture to end of angiography

 mTICI 2a or less

  

0.039*

 ≤1:00 h

 >1:00 h

0/11 (0 %)

10/30 (33 %)

11/11 (100 %)

20/30 (67 %)

Final revascularization result

 mTICI ≤ 2a

 mTICI ≥ 2b

10/41 (25 %)

13/135 (10 %)

31/41 (75 %)

122/135 (90 %)

0.031*

Tandem occlusion

 Stenting of a preceding vessel

 No Stenting of a preceding vessel

8/42 (19 %)

15/134 (11 %)

34/42 (81 %)

119/134 (89 %)

0.20 (ns)

Table 6

Subgroup analysis comparing Solitaire FR and Penumbra 3D

Complication

Solitaire FR subgroup (n = 65), n (%)

Penumbra 3D subgroup (n = 50), n (%)

p value

All

7/65 (11 %)

7/50 (14 %)

0.78 (ns)

sICH

Procedure related

2/65 (3 %)

3/50 (6 %)

1 (2 %)

0.65 (ns)

Emboli to new vascular territories

3/65 (5 %)

1/50 (2 %)

0.63 (ns)

Vessel dissection

1/65 (2 %)

1/50 (2 %)

1.0 (ns)

Vasospasm of access vessel

1/65 (2 %)

2/50 (4 %)

0.58 (ns)

No IVT, normal coagulation parameters

Research in context

Systematic review

As reported above, complications other than sICH in MT when utilizing the Solitaire FR or the Penumbra 3D Separator are infrequent in MT. In order to compare our study results, we conducted a systematic review focused on the widely used Solitaire FR device and the Penumbra 3D Separator, which is a new device for MT. We searched for trials published in PubMed library between Jan 1st, 1990 and October 30th 2013, based on the following search terms: “complications” crossed with “endovascular treatment,” “mechanical thrombectomy” crossed with “ischemic stroke” or “cerebral infarction” and “Solitaire” or “Penumbra 3D,” yielding 147 results. These publications were screened for any prospective or retrospective study, registry or any case series covering 50 or more cases, which were treated by MT deploying either the Solitaire FR or the Penumbra 3D Separator and reporting about complications. After screening all abstracts, we identified 49 studies or registries substantially matching our search items. Only one of these focused on complications in mechanical thrombectomy, analyzing the complications reported within the SWIFT study data [16]. One study about the Penumbra 3D Separator reported no procedural complications in 20 cases [13]. There were five studies exclusively dealing with using the Solitaire AB device for MT and 33 studies covered less than 50 patients and did not undergo further analysis. We found eight studies covering 50 or more patients who received MT by the means of the Solitaire FR and these studies were analyzed for reported complications and complication rates, respectively. Complication rates were reported inconsistently (Table 6); sICH was the only complication reported in all studies according to the ECASS criteria [2]. ENT where seen in 0 to 3.7 % of cases. Vessel dissection occurred in 1.5 to 4.5 % of cases. Unfortunately, the rate of vessel dissections as well as the ENT rate was only mentioned in three studies [15, 16, 21, 23] (Table 1). Overall, the documentation of complications in MT has not been in the scientific focus and only limited data is available in the literature.

Discussion

Any discussion about the future potential and the role of MT in the setting of acute stroke treatment will be compromised by a lack of profound knowledge about the inherent dangers of the procedure and its potential to negatively influence the course of the disease by adding to the cerebral tissue damage due to complications. Apparently, data on the frequency of these events and on their clinical impact is scarce in the literature; most publications have focused on the potential benefit of MT not sufficiently analyzing the downside. In the present study, we focused on the complication rate of MT in an experienced, high volume neurocenter, providing interventional stroke care on a 24/7 basis. In this context, we observed a statistically significant correlation of the frequency of complications with a prolonged procedure time (groin puncture to final result ≥1 h) as well as with an unfavorable revascularization result (mTICI ≤ 2a) and an unfavorable clinical outcome. These findings are in accordance with data published recently by Spiotta et al. [26] and Hassan et al. [27] who reported a significant impact of a prolonged time from groin puncture to revascularization on the clinical outcome underlining the importance of a swift and complete revascularization. Although we did not analyze the correlation of a prolonged time from groin puncture to revascularization with an unfavorable outcome, a link between complications, a prolonged time from groin puncture to revascularization and an unfavorable outcome becomes more evident. A causal interconnection between the abovementioned factors is further supported by our finding that there was no significant correlation of the procedural complication rate with a time from symptom onset to revascularization below or above 4.5 h. This was also true for the group of patients with concomitant IVT, which appears to be counterintuitive at first glance. Our findings hint at the importance of the individual “time window” which results from differences in collateral arterial support and the “vascular reserve” of each individual patient, which should be accounted for in future trials. It has become common practice in appropriate infrastructural settings to start with IVT and to then transfer stroke patients with major vessel occlusions to endovascular neurocenters for MT (concept of “drip and ship” or “bridging”) [28] This was also the case in 76/176 (43 %) of patients in our cohort. Those patients had a “time from symptom onset to admission” interval that was almost 1 h longer compared to the patients who were directly admitted to our center. Interestingly, we found no significant difference between the frequency of complications in those groups, which—from a technical perspective—supports the “drip and ship” concept.

Regarding specific technical aspects, we did not observe any significant differences in the occurrence of complications between patients who received MT with the Solitaire FR and proximal aspiration vs. patients treated with the Penumbra 3D Separator with lesional aspiration. This finding had to be expected, as the numbers in this single-center experience are clearly too small in order to show subtle differences in closely related conceptual designs. This limited experience indicates that the two approaches might not differ in their inherent risk for a procedural complication; more sophisticated multicenter approaches are needed to elucidate this topic. Regarding the Solitaire FR device, our self-reported complication rate stays in line with other large-scaled studies of the Solitaire FR in MT [11, 14, 15, 21, 23]. Additionally, important information on the role of technical factors such as emergency stenting of a preceding vessel could be gained. We did not find an increase in the complication rate in this subgroup, which comprised 42 patients. This stands in contrast to other published series, which reported rates between 9.7 and 20 % [19, 29, 30]. Factors influencing this result might be the experience of the site (>50 elective extracranial stenting procedures per year in symptomatic high grade stenosis) and the antegrade approach under general anesthesia. From a clinician’s perspective, the pre-interventional morbidity, expressed by the NIHSS score, was not associated with a higher procedural complication rate.

Conclusion

A deep understanding of procedural complications in MT is necessary for an optimized treatment of stroke patients who receive endovascular therapy. Overall, the frequency of procedure-related complications lies within acceptable limits for an emergency procedure. The severity of stroke symptoms and concomitant IVT do not seem to lead to a higher procedural complication rate. Mechanical thrombectomy does not add significantly to the stroke patients’ risk of sICH; it does though have an innate risk of stroke in an initially uninvolved territory due to procedural thrombus migration. Furthermore, a prolonged endovascular procedure beyond an hour is correlated with higher complication rates, which underlines the importance of a swift and complete revascularization.

Limitations

The basic limitations of this study are the single-center retrospective design and the missing clinical 3-month follow up. Adjudication of the endpoints, e.g., angiographic results, complications, and clinical outcome was performed locally at the reporting site, without a core laboratory or requirement of an independent adjudicator. This adjudication may be biased toward better technical results. Furthermore, six out of eight sICH were in the group that had received prior IVT (134/176 patients). We do not know if these six sICH were related to the IVT, the MT, or both.

Notes

Conflict of interest

We declare that we have no conflict of interest.

Supplementary material

234_2014_1352_MOESM1_ESM.docx (19 kb)
ESM 1(DOCX 18 kb)

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Daniel Behme
    • 1
  • Ludger Gondecki
    • 1
  • Sarah Fiethen
    • 2
  • Annika Kowoll
    • 1
  • Anastasios Mpotsaris
    • 1
    • 3
  • Werner Weber
    • 1
    • 2
  1. 1.Klinikum Vest - Knappschaftskrankenhaus RecklinghausenKlinik für Radiologie, Neuroradiologie und Interventionelle TherapieRecklinghausenGermany
  2. 2.Ruhr-Universität-Bochum, Universitätsklinikum KnappschaftskrankenhausInstitut für Diagnostische und Interventionelle Radologie, Neuroradiologie und NuklearmedizinBochumGermany
  3. 3.Universität zu Köln, UniversitätsklinikInstitut für Radiologie, Abteilung für Neuroradiologie KölnGermany

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