Radiol med DOI 10.1007/s11547-015-0501-9
Sequential endovascular thrombectomy approach (SETA) to acute ischemic stroke: preliminary single‑centre results and cost analysis Alessio Comai · Thomas Haglmüller · Federica Ferro · Elisa Dall’Ora · Roberto Currò Dossi · Giampietro Bonatti
Received: 27 August 2014 / Accepted: 19 January 2015 © Italian Society of Medical Radiology 2015
Abstract Introduction We report the preliminary results of a singlecentre experience in the endovascular treatment (ET) of acute ischemic stroke (AIS) with a sequential endovascular thrombectomy approach (SETA), which comprehends a direct aspiration first-pass technique (ADAPT) eventually followed by stent retriever thrombectomy. Materials and methods We prospectively analyzed data from 16 patients with severe to moderate AIS and CT angiography demonstration of large intracranial vessel occlusion treated with SETA between July 2013 and March 2014. We evaluated recanalization rate, clinical outcome after 90 days as well as differential costs of aspiration and stent-assisted thrombectomy. Results A group of 16 patients met the eligibility criteria to undergo ET with a baseline NIHSS score of 22 (range 12–39). In 15/16 cases, we obtained target vessel recanalization, 11 cases with ADAPT technique alone. Modified rankin score (mRS) at 90 days follow-up was ≤2 in 9/16 patients (56 %). ADAPT technique had a lower devicerelated cost than stent-assisted thrombectomy leading to an overall saving of −2,747.28 €. Conclusions Our preliminary data suggest that a SETA beginning with direct aspiration could be useful to optimize ET of stroke in terms of invasiveness, safety and cost-effectiveness allowing recanalization with low complication rate. A. Comai (*) · T. Haglmüller · F. Ferro · G. Bonatti Department of Radiology, Bolzano Central Hospital, Bolzano, Italy e-mail: [email protected]
E. Dall’Ora · R. Currò Dossi Stroke Unit, Department of Internal Medicine, Bolzano Central Hospital, via Lorenz Boehler 5, 39100 Bolzano, Italy
Keywords Stroke · Endovascular treatment · Mechanical thrombectomy · Aspiration thrombectomy
Introduction Stroke is the third cause of death and the first cause of disability in Europe. It is commonly associated with significant neurological deficit, high level of dependency and high mortality. Intravenous tissue plasminogen activator [tPA; alteplase (Actilyse, Boehringer Ingelheim)] is the only proven reperfusion therapy for acute ischemic stroke (AIS) according a high-level evidence . Early vessel recanalization in AIS has been shown to strongly correlate with improved clinical outcome and reduced mortality . Nevertheless, only few patients with AIS meet current eligibility criteria for the administration of intravenous thrombolytic agents. Particularly critical is the time window from symptom onset to treatment, which has to be inferior to 4.5 h . Endovascular treatment (ET) with various thrombectomy devices has been recently shown to be effective up to 8 h after the onset of stroke symptoms with a low complications rate [4–6]. Moreover, mechanical thrombectomy techniques proved better recanalization rates than intravenous tPA or intra-arterial thrombolysis alone, especially in large intracranial vessel occlusion [7, 8]. Although recent randomized controlled trials (RCT) showed that ET is not superior to systemic tPA for AIS in terms of clinical outcome, selected patients may still take advantage of an endovascular approach [9–11]. A limit of these RCTs is heterogeneity of technical approaches to thrombectomy including intra-arterial t-PA, merci retrievers, stent retrievers as Solitaire, first generation aspiration catheter of penumbra system. The aim of our study was to report preliminary results of a standardized sequential approach to
ET of AIS in patients not responsive to intravenous t-PA or with contraindications to pharmacological treatment.
Before treatment, informed consent was obtained from either the patient, if conscious, or a legal representative. The study protocol has been approved by our Ethic Committee.
Patient selection From July 2013, we prospectively acquired a database of consecutive patients, who underwent sequential endovascular thrombectomy approach (SETA) and followed them up for a period of at least 90 days. All patients were included in the international registry of SITS (safe implementation of treatments in stroke), an academic-driven, non-profit, international collaboration based at Karolinska Institutet and Karolinska University Hospital in Sweden. Criteria for selection of patients were: moderate to severe ischemic stroke with an NIHSS score ≥12 and a time window of less than 6 h for anterior circulation and 12 h for posterior circulation; no or poor neurologic response to iv rt-PA (decrease of NIHSS score of at least four points) or contraindications to iv rt-PA. All patients with moderate to severe ischemic stroke underwent native CT to exclude hemorrhage and assess ASPECT (alberta stroke program early CT) score and immediate CT angiography to demonstrate a large-vessel occlusion, i.e., internal carotid artery (ICA), M1 tract of middle cerebral artery (MCA) and basilar artery (BA). In patients with undetermined onset time, as for example wake-up stroke, MRI was obtained to evaluate DWI/FLAIR mismatch, defined as visible acute ischemic lesion on DWI with no traceable parenchymal hyperintensity in the corresponding region on FLAIR imaging . All patients were evaluated by a stroke-dedicated neurologist and treatment was performed by a general interventional radiologist available on-call 24 h a day. Decision to ET was collegially taken by a neurologist and a general interventional radiologist. Technical success was defined as recanalization of the target vessel as assessed by two experienced interventional radiologists according to TICI score including score 2a, 2b and 3 (thrombolysis in cerebral ischemia) . All patients underwent dual-energy CT immediately after the procedure and 24 h later to evaluate extent of ischemic area and detect eventual hemorrhage. Symptomatic intracranial hemorrhage (sICH) was defined as parenchymal hematoma type II or subarachnoid hemorrhage with neurologic deterioration leading to an increase of National Institutes of Health Stroke Scale (NIHSS) score >4 or leading to death within 36 h of treatment . Neurologic evaluation was quantified according to NIHSS at admission, 24 h and 7 days after intervention. Modified rankin scale (mRS) score was assessed at 90 days follow-up. Good neurological outcome was defined as mRS ≤2.
Technique Sequential endovascular thrombectomy approach followed systemic thrombolytic treatment, when indicated, and consisted of first-line manual aspiration by means of 5MAX or 4MAX reperfusion catheter (Penumbra, Alameda/CA, USA) brought at the proximal site of occlusion with a 0.025 coaxial velocity microcatherer (Penumbra, Alameda/CA, USA) and a 0.014 microwire. Thromboaspiration maneuvers were repeated until recanalization of target vessel. If no thrombotic material was withdrawn and angiographic controls appeared unmodified, we switched to a second-line mechanical thrombectomy maneuver delivering a Solitaire flow restoration (FR) stent retriever (ev3/Covidien Vascular Therapies, Irvine/CA, USA) through the reperfusion catheter itself (Fig. 1). The latter acts as a distal access catheter facilitating delivery of the stent retriever through the occlusion site and consenting distal aspiration during retrieval.
Cost analysis Current cost of all angiographic devices involved in standardized procedures was calculated and compared, including femoral sheath, diagnostic catheter, guide catheter and microcatheter, guidewires, reperfusion catheter and stent retriever. Exceptional devices as, for example, stents for ICA dissection or optional catheters were not considered. Pricing data were obtained by the Bursar office of the hospital at the time of study. We excluded costs of consumable goods, negligible in the order of magnitude and common to different techniques, such as sterile table kit, syringes, needles, heparinized saline solution and drip infusion set. Personnel and administrative costs were also excluded because they are common to different techniques and do not contribute to the differential cost.
Results In the period between July 2013 and March 2014, 58 patients presented at our hospital with AIS and underwent systemic thrombolysis and/or mechanical thrombectomy. 16/58 patients affected by a large-vessel AIS met the selection criteria and were treated with SETA, nine cases with occlusion of M1 tract of a MCA, three cases with carotid
Radiol med Fig. 1 Treatment flow chart of patients with a documented large intracranial vessel occlusion according to the sequential endovascular approach (SETA) adopted in our center
Table 1 Clinical and technical data Patient no.
mRS 90 days
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
83 53 46 75 47 44 55 65 73 80 52 74 74 53 80
Basilar artery Right MCA Right MCA Left MCA Basilar artery Left ICA Right ICA Right MCA + ICA* Left MCA Left MCA Right MCA Right MCA Right MCA Left MCA Left ICA
33 12 20 19 22 20 18 16 19 27 17 23 19 21 26
3 3 3 3 2b 3 2b 3 2b 1 2b 2b 3 2a 3
76 104 37 114 227 111 161 66 164 155 66 82 175 149 111
36 38 108 43 101 106 117 122 35 121 74 38 53 43 31
5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX 5MAX
None None Solitaire FR None None Solitaire FR Solitaire FR Solitaire FR None Solitaire FR None None None None None
0 0 1 6 5 3 3 0 1 6 2 0 6 2 6
+ + + − + + + + + − + − − + +
TICI thrombolysis in cerebral infarction, DTP door to puncture, PTR puncture to revascularization time *Tandem occlusion: acute dissection of ICA with embolic occlusion of omolateral MCA
apex occlusion, three cases with BA occlusion and one tandem occlusion of ICA and omolateral MCA. Table 1 reports complete data for the treated patients. Mean NIHSS score at baseline was 22, ranging from 12 to 39.
Recanalization of target vessel was obtained in 15/16 (94 %) cases (TICI 2/3) with an optimal revascularization of distal capillary bed (TICI score 2b/3) in 14/16 cases. All patients had a baseline TICI score of 0 at presentation. In
Fig. 2 CT angiography shows an occlusion of left MCA (a; white arrow). Left internal carotid angiography (b) confirms the MCA occlusion just downstream to the lenticulostriate arteries (white arrow)
11/15 (73 %) cases, recanalization was obtained with firstline aspiration approach alone, i.e., with direct aspiration technique (ADAPT). In the remaining 4/15 cases, an adjunctive stent retriever was needed to complete recanalization. In the ADAPT group, mean procedural time from groin puncture to recanalization was 47 min [Puncture Time to Recanalization (PTR)] (24–101 min). In the combined aspiration and stent retriever group, it was 115 min (106–122 min). Nine patients (56 %) had a good clinical outcome (mRS ≤ 2) at day 90 after procedure, two of whom had requested the adjunctive use of stent retriever to obtain recanalization. Overall mortality was 4/16, in one case owing to massive reperfusion hemorrhage and in one case, where thrombectomy was inefficient, to cerebral infarction with massive edema. The other two deceases were related to non-cerebral events. Regardless of the thrombectomy technique, our common approach consisted of a femoral sheath, a diagnostic 5F catheter and a 0.035 in hydrophilic guidewire for diagnostic phase, followed by a 8F or 7F guide catheter on an exchange wire. For aspiration thrombectomy, the largest caliber aspiration catheter that the vessel would accomodate was advanced through the guide catheter and coaxially over a 0.025 in. microcatheter. Total cost of materials for aspiration thrombectomy in our center was 2,585.93 €, and that of a two-step thrombectomy including reperfusion catheter and stent retriever was 6,329.93 €. Total cost of a stent retriever thrombectomy without aspiration catheter, not adopted as a first-line technique in this study, is 5,333.75 €. The latter includes a guide catheter, a microcatheter and a Solitaire FR stent retriever besides the previously mentioned devices. Differential cost between ADAPT technique and stent-assisted thrombectomy is −2,747.82 €. Given the fact that in 11/16 cases aspiration alone was efficient to obtain recanalization, we can estimate a saving of 32,226 € in our case series by choosing the more costeffective aspiration approach.
Discussion The first PS aspiration system (Penumbra, Alameda/CA, USA) for ET of intracranial large-vessel occlusion became available in 2008 and included a reperfusion catheter (0.041, 0.032 and 0.028 in.) and a separator guidewire [15, 16]. Previously endovascular techniques for stroke treatment included intra-arterial administration of pro-urokinase and the first world-wide available device for mechanical thrombectomy called merci retriever (Concentric Medical, Mountain View/CA, USA) [17, 18]. Nowadays, the most widely adopted device for vessel recanalization is stent retriever due to the large amount of studies reporting good technical and clinical results. In particular, higher recanalization rates with stent retrievers than with the merci retriever have been described [7, 19]. Aspiration thrombectomy approach made a comeback thanks to advances in catheter technology allowing largebore catheter to reach intracranial vessels at the site of occlusion and directly aspirate the clot, a technique defined with the acronym ADAPT (a direct pass first-pass aspiration technique) [20, 21]. We adopted the largest catheter fitting the occluded vessel and that was penumbra 5MAX reperfusion catheter (Penumbra, Alameda/CA, USA) in all cases but one. Aspiration technique is less invasive than stent-assisted thrombectomy and easier to perform even by a general interventional radiologist: the reperfusion catheter has to be advanced proximally to the occlusion without navigating in distal intracranial vessels and without perforating and disrupting the thrombus (Figs. 2, 3). When this technique is successful, it consents to reduce the use of other devices, such as stent retriever or separator, leading to a much lower device-related cost . In cases where aspiration technique proves ineffective, a second level technique can be adopted as, for example, by introducing a stent retriever through the same reperfusion catheter. In this case, the reperfusion catheter facilitates delivery of
Radiol med Fig. 3 Left internal carotid artery angiogram demonstrates reperfusion of MCA (a). Whitish Y-shaped embolus is shown near the reperfusion catheter (b). The peculiar shape represents the middle cerebral artery bifurcation
the retriever at the occlusion site acting as a distal access catheter. Moreover, distal aspiration can be performed during stent retrieval, a combinative technique that has been already described as “Solumbra”, a crasis of Solitaire and penumbra . Such a two-step approach to thrombectomy has been already described with positive technical and clinical results [22–25]. ADAPT technique has proved to be faster and more effective than any series reported in the literature [20–22]. In our series, 11 of 16 cases were successfully recanalized with aspiration alone limiting the use of stent retriever to five cases. Combining the two techniques, good recanalization rate (TICI > 2a) was obtained in almost all cases (15/16). Moreover, there is a temporal trend toward a higher recanalization rate with ADAPT approach as technical confidence grows and devices improve . Direct aspiration of thrombus was previously described as an alternative technique to more conventional strategies or with previous generation smaller catheter [26–28]. The increased internal diameter of the 5MAX reperfusion catheter provides an increased contact area at the catheter tip-thrombus interface. In addition, it is more capacious along its proximal segment, increasing its luminal volume and thereby resulting in an increased aspiration capacity and force over previous versions of aspiration catheters [21, 28]. Four patients died during hospitalization (25 %), two for other reasons than stroke itself (sepsis in acute cholecystitis and myocardial infarct). 2 of 4 patients deceased because of stroke, both 80 years old, one with poor recanalization of the left MCA (TICI 1) despite combined technique, and the other one after developing a post-reperfusion parenchymal hematoma with massive edema requiring craniotomy. The latter had been successfully treated with aspiration alone 142 min after onset of a left ICA occlusion. This complication was probably due to a large infarction core, a condition which can sometimes appear within the usual timing
range for treatment. In this case, a poor collateralization was shown at CT angiography favouring rapid evolution of the ischemic process. Perfusion CT and MRI can play an important role in the selection of patients allowing the distinction of ischemic penumbra and infarct core . This was the only symptomatic hemorrhagic complication in our series (6 %). Despite the low number of cases, incidence of sICH is much lower than the cutoff value of 12 % stipulated as standards of practice by the international multisociety guidelines of 2013 . Complications have been reported to be higher with stent retriever thrombectomy than with penumbra system thrombectomy, albeit with similar positive clinical outcome rates [20–22]. We had two cases of emboli to new territories (ENT) occurring one after aspiration thrombectomy and the other after combined aspiration–stent retrieve technique. Aspiration alone is considered to be associated with a lower ENT rate than with other mechanical techniques because of complete engaging and removal of thrombus without its fragmentation, as possible using separator or stent retrievers. In fact, ENT has been reported to occur in up to 14 % of cases with stent retrievers [7, 19]. SETA-combined technique includes, in case of stent retriever delivery, the possibility to apply aspiration during stent withdrawal to preclude the spread of emboli. Moreover, fragmentation of thrombus with the separator has been shown to originate small emboli that migrate in peripheral vessels, not suitable for distal thrombectomy and unfavorable for collateralization . Future development thrombectomy should aim to better patient selection, as for example, on the basis of stroke etiology. The cause of occlusion could be related to the composition and the physical characteristics of thrombus such as hardness and elasticity and influence responsivity to different thrombectomy approaches as well as lysability [32–34].
Major limitation of our study is the low patient’s number. Although preliminary, our results are encouraging not only in terms of technical success, similarly to other reports on the aspiration technique, but above all in terms of clinical outcome also which is reported to be approximately 40 % . At 90 days follow-up after treatment, 9 patients of 16 had a positive clinical outcome with mRS = 0 in 5 patients, mRS = 1 in 2 patients, mRS = 2 in 2 patients. We adhered to the quality benchmarks suggested by the international multispeciality document recently issued by a consensus of many principal international societies, in particular by strictly applying selection criteria . Time to treatment is another fundamental parameter, which affects clinical efficacy of stroke therapy and adherence to the time intervals suggested by the same paper could have positively affected clinical outcomes of our patients [30, 35]. Our differential cost analysis considered only current price of devices we use in standardized ETs. The most expensive devices are reperfusion catheter for ADAPT technique and stent retriever for stent-assisted thrombectomy. The cost ratio of these two devices is about 1:3 and mainly accounts for the high differential cost of the techniques. The use of aspiration as an initial approach is on average the less expensive method to achieve acceptable recanalization rates with low complication rates. Stent retrievers consent to obtain higher recanalization rate in difficult cases. As suggested by Turk et al. , the most cost-effective approach to a large-vessel occlusion might be what we define SETA, i.e., to attempt a brief direct aspiration with a large bore first and if this fails then proceed with other devices, such as a stent retriever. Interventional treatment strategies with adjunctive mechanical thrombectomy or intra-arterial thrombolysis appear to have an acceptable cost-effectiveness profile compared to IV tPA alone for large-vessel stroke based on currently available data . Heterogeneous technique and devices have been included in recent RCTs possibly limiting the demonstration of clinical efficacy of endovascular approach and resulting in non-superiority of mechanical thrombectomy to systemic treatment [10–12]. We consider endovascular approach as a rescue treatment in patients affected by occlusion of large intracranial vessel who receive full dose iv t-PA treatment without showing any neurological response or who have contraindication to pharmacological treatment. Standardization of endovascular approach should be needed to evaluate effective contribution of interventional radiology in the treatment of these patients. We adopted a sequential approach, which could consent to shorten procedural time, to grade invasiveness and likely to limit complications and to reduce procedural costs. Nevertheless, a wider number of cases are required to confirm efficacy and safety of our approach.
Conclusions Our preliminary data suggest that sequential endovascular approach (SETA) with first-line direct aspiration could be useful to optimize ET of stroke in terms of efficacy, safety and cost-effectiveness. Conflict of interest The authors declare no conflict of interest
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