Mechanical thrombectomy in severe acute stroke: preliminary results of the Solitaire stent
- Anastasios Mpotsaris,
- Matthias Bussmeyer,
- Christian Loehr,
- Michael Oelerich1,
- Helmut Buchner2,
- Werner Weber1
- 1Klinik für Radiologie, Neuroradiologie und interventionelle Therapie, Klinikum Vest, Knappschaftskrankenhaus Recklinghausen, Recklinghausen, Germany
- 2Klinik für Neurologie und klinische Neurophysiologie, Klinikum Vest, Knappschaftskrankenhaus Recklinghausen, Recklinghausen, Germany
- Correspondence to Dr Anastasios Mpotsaris, Klinik für Radiologie, Neuroradiologie und interventionelle Therapie, Klinikum Vest, Knappschaftskrankenhaus Recklinghausen, Dorstener Str. 151, 45657 Recklinghausen, Germany; mpotsaris{at}unitybox.de
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Contributors AM and MB contributed equally to this article.
- Received 29 July 2010
- Revised 5 November 2010
- Accepted 6 November 2010
- Published Online First 6 January 2011
- Stroke
- thrombectomy
- rTPA
- outcome
- thrombolysis
- cerebral blood flow
- cerebrovascular disease
- clinical neurology
Introduction
Intravenous recombinant tissue plasminogen activator (rTPA) therapy has limited recanalisation-rates in large artery occlusions (nadir of 5.9% in Carotid-T-Occlusions).1 Therefore, we prospectively evaluated the Solitaire stent (versions AB and FR, ev3 Inc., Plymouth, Minnesota, USA) in mechanical thrombectomy in acute ischaemic stroke.
Materials and methods
Acute stroke patients were triaged on admission for potential mechanical thrombectomy.
Inclusion criteria
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– Age ≤80
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– NIHSS score ≥10, less if symptoms were fluctuating
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– Onset-to-treatment-time ≤4.5 h or secondary worsening (increase in NIHSS score ≥4). When symptom onset was unclear, patients were eligible if there was mismatch between symptoms and CT-scan
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– Any brainstem syndrome.
Exclusion criteria
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– Cerebral haemorrhage. Acute infarction >1/3 of middle cerebral artery (MCA) territory on CT-scan.
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– Prestroke modified Rankin Scale (mRS) score ≥4
Eligible patients had immediate CT-angiography without delaying intravenous rTPA-thrombolysis if applicable according to the guidelines of the German Neurological Society (DGN). In case of occlusion of either the internal carotid artery (ICA), the MCA-M1-segment or the basilar artery (BA) mechanical thrombectomy was carried out. Up to four clot extraction maneuvers were performed. Any preceding stenosis was a priori stented. These patients received intravenous eptifibatide for 24 h to prevent in-stent-thrombosis; its short half-life would allow for emergency decompressive craniectomy. Combination of rTPA and eptifibatide is safe.2
NIHSS and mRS scores were assessed on admission and discharge. mRS ≤2 on discharge was defined as good functional outcome. ‘Thrombolysis in Myocardial Infarction’ (TIMI) scores of 2 or 3 were defined as successful recanalisation.
Results
Twenty-six patients were eligible for mechanical thrombectomy with the Solitaire stent since October 2009. In 22/26 cases (85%), the moment of symptom onset was clear, averaging 64 min till arrival (table 1). The average NIHSS score on arrival amounted to 16, ranging from 7 to 31. Ninety-two per cent had a NIHSS score ≥10 and 96% had a mRS score ≥4. Prior to mechanical thrombectomy 19/26 patients (73%) received intravenous rTPA. Acute a priori stenting of the ICA was necessary in 12 cases (46%). The revascularisation rate was 88%; the optimum (TIMI 3) was reached in 69%. In 50%, the first attempt led to recanalisation. Five of six carotid-T-occlusions reached TIMI 3.
Characteristics of patients, procedural technique and outcome
Outcome
Twenty-four of 26 patients survived the stroke, averaging 7.4 on the NIHSS on discharge. Two patients died and were completely excluded from all NIHSS statistics. Ten patients (38%) had a good clinical outcome; mean hospitalisation time was 19 days. Five patients (19%) had no residual symptoms at all. Eighteen patients (69%) showed improvement. Two of 23 patients with anterior circulation stroke died; the 21 survivors had a mean initial NIHSS score of 15.4 and 7.6 on discharge. Nine patients (39%) had a good outcome. Six patients (26%) presented with carotid T occlusion; 3 of them reached a good outcome although 4/6 suffered from tandem stenosis. Acute ICA stenting proximal to the occlusion site did not significantly influence the outcome. Of three occlusions in the posterior circulation (2 BA, 1 VA) only one had a good outcome. Two of the 19 bridging-patients died at the hospital. The remaining 17 bridging-patients had a mean NIHSS score of 15.3 on admission and 5.8 on discharge (62% reduction). Good outcome was reached by 8/19 bridging-patients (42%). Seven patients ineligible for bridging had an average base NIHSS score of 13.7 and 9.6 on discharge (30% reduction); 2/7 reached a good outcome (29%). NIHSS score reduction in the bridging group was significantly better (p=0.045; Mann–Whitney U test).
Overall mean time from symptom onset to mechanical revascularisation (OTR) was 327 min (5:27 h), including four patients with only last well time known. For the subgroup with clear moment of symptom onset (85%) the mean OTR-interval was 280 min (4:40 h). Patients were stratified into an early, intermediate and late treatment group defined as:
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–Early group (n=10): OTR-interval ≤4.5 h (approved time frame for intravenous thrombolysis)5
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– Intermediate group (n=10): OTR-interval of 4.5–6 h (limit for intra-arterial thrombolysis in PROACT II)
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– Late group (n=6): OTR-interval >6 h
In the late OTR group, 2/6 patients (33%) had a good outcome; in the intermediate OTR group this was true for three patients (30%). Pertaining to the early treatment group, 5/10 patients (50%) had a good outcome; four of them (40%) had no neurological deficit on discharge. Between group mRS differences did not reach statistical significance, probably due to small numbers. NIHSS score reduction showed a statistical trend in favour of early treatment (p=0.06; Mann–Whitney U test).
Discussion
The study was neither blinded nor controlled and subgroup analyses are based on small numbers.
The Solitaire stent is technically feasible and safe; we observed no procedural complications. Its performance has to be compared with established treatments like rTPA alone and intra-arterial thrombolysis.
rTPA alone, applied within 4.5 h of onset, led to a good outcome in 49% in a pooled analysis of NINDS 1&2, ECASS 1&2 and ATLANTIS A&B trials. However, our study-collective consists exclusively of patients with proven large artery occlusion, resulting in a higher mean base NIHSS (16 vs 11). Furthermore, ECASS excluded patients with severe hemispheric syndromes. Our treatment strategy led to an equivalent outcome in the early treatment subgroup in spite of the initially worse prognosis. rTPA alone has no significant benefit beyond 4.5 h3; interestingly two of six patients in our late OTR subgroup had a good outcome with thrombectomy alone.
PROACT II (intra-arterial thrombolysis) reported a good outcome in 40%. A history of stroke in the last 6 weeks, a time interval of >6 h and tandem stenosis led to a priori exclusion. We reached a comparable good outcome (38%) without these exclusions.
Our bridging-patients had a higher NIHSS score reduction (p=0.06) than non-bridging patients. Different mean time-frames acted as potential confounder. Nevertheless, bridging should be applied whenever possible; rTPA in thrombectomy is safe.4 Good outcome is associated with early revascularization5; unfortunately the recanalisation rate of rTPA alone drops to 5.9% in distal ICA-occlusions.1 Our study implies that mechanical thrombectomy with the Solitaire stent may lead to recanalisation rates >85% in anterior large vessel occlusions and may increase the rate of good outcome substantially for these patients with an otherwise poor prognosis. Under optimum conditions we were able to recanalise all large artery occlusions within a time frame of less than 4.5 h and reach a significant reduction in NIHSS score in conjunction with intravenous rTPA, resulting in good functional outcome for 50% of patients in the early treatment subgroup even in case of an underlying tandem occlusion. Although these initial results are promising, larger subsequent studies should include longer term outcome measures.
Footnotes
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Competing interests None.
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Ethics approval This study was conducted with the approval of the Institutional Ethics Board.
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Provenance and peer review Not commissioned; externally peer reviewed.
