Abstract
Introduction
The Sofia 6-French PLUS catheter is a recently approved aspiration catheter for use in neuro-endovascular procedures. The description of Sofia 6-French PLUS use in acute ischemic stroke is limited.
Objective
The purpose of this article is to describe our initial experience with the new Sofia 6-French PLUS catheter for treatment of acute ischemic stroke and to report on its safety and efficacy.
Methods
We performed a retrospective study of 54 thrombectomy cases treated with the Sofia 6-French PLUS catheter. Mean patient age and admission National Institutes of Health Stroke Scale score were 65.30 (1.92) and 15.98 (0.89), respectively. The most common sites of vessel occlusion included the M1 segment (50%) and internal carotid artery (31%). Thrombectomy was performed using the direct aspiration first pass technique and/or aspiration in conjunction with a stent retriever.
Results
Successful navigation of the Sofia 6-French PLUS catheter to the site of thromboembolus was achieved in 94% of cases. Revascularization was achieved in a total of 47 cases (87%). Mean time from groin access to revascularization was 42.79 (3.23) min. There were no catheter-related complications. Final outcome data was available for 44 patients (81%). Of these patients, 41% achieved a good outcome (modified Rankin scale score of 0–2) at 60–90 day follow-up, 41% had a poor outcome (modified Rankin 3–5) and eight patients died (18%).
Conclusions
We demonstrate the safe and effective use of the Sofia 6-French PLUS catheter for treatment of acute ischemic stroke. Future studies in the form of a randomized clinical trial or multicenter registry are warranted to further evaluate its comparative safety and efficacy.
Keywords: Stroke, thrombectomy, direct aspiration first pass technique, Sofia, large-vessel occlusion
Introduction
Endovascular mechanical thrombectomy has dramatically improved patient outcomes after acute ischemic stroke.1–7 The most recent guidelines for the early management of patients with acute ischemic stroke from the American Heart Association (AHA) recommend mechanical thrombectomy with stent retrievers for patients meeting appropriate criteria with the goal of achieving thrombolysis in cerebral infarction (TICI) grade 2b or 3 angiographic revascularization in order to increase probability of a good outcome.8 Although stent retrievers remain the first-line device for thrombectomy, the AHA guidelines also state that use of other thrombectomy devices may be reasonable in some cases.8
The novel thrombectomy technique, referred to as the direct aspiration first pass technique (ADAPT), has been shown to provide rapid and safe revascularization. This method involves navigating a distal access catheter to the proximal face of the occlusion followed by the direct application of suction via the distal catheter.9 Alternative thrombectomy techniques utilizing stent retrievers in conjunction with large-bore intracranial aspiration catheters have been described.10–12 Difficulty in navigating tortuous vasculature with intermediate or distal access/suction catheters may prohibit one from safely and rapidly achieving revascularization. Catheters may become caught within a tortuous internal carotid artery or at the ledge created by ophthalmic artery origin. The recently developed Soft torquable catheter Optimized for Intracranial Access (Sofia) PLUS catheter (MicroVention Terumo, Tustin, California, USA) is a highly navigable catheter with a soft distal tip and large inner bore that can facilitate rapid distal access and revascularization.
The Sofia 6-French (6F) catheter was approved for use by the Food and Drug Administration in early 2015 and serves as a second generation to the original 5-French Sofia Distal Access catheter.13 Recently, a longer, Sofia 6F Plus version received (FDA) approval for thrombectomy indication. The Sofia (6F) PLUS catheter possesses a larger 0.070-inch wide lumen to allow for aspiration and is uniquely engineered with a soft, steam-shapeable tip and torquable shaft. It has a hybrid coil and braid design which provides catheter stability while facilitating navigation of tortuous distal vessels for direct aspiration or deployment of adjunctive treatment devices.14 Two recent multi-center studies have reported the safe and effective use of the Sofia PLUS catheter in treatment of acute ischemic stroke.15,16 The first series, published in Europe in 2016 by Möhlenbruch et al., describes the use of the Sofia Plus catheter in 85 patients with a median baseline National Institutes of Health Stroke Scale (NIHSS) score of 18 and an overall revascularization rate (TICI ≥ 2b) of 96.5%.16 The second report by Shallwani et al. details use of the Sofia PLUS catheter in a series of 41 cases of acute ischemic stroke with successful revascularization occurring in 90.2% of patients.15 The purpose of this study was to report the safety and efficacy associated with use of the Sofia PLUS catheter for treatment of acute ischemic stroke in a prospective population admitted to a large metropolitan US academic medical center.
Methods
Study population/setting
This study was performed at a large metropolitan academic medical center with Institutional Review Board Approval (Protocol HP-00083153). We identified 54 nonconsecutive patients treated for acute ischemic stroke with the Sofia (6F) PLUS catheter from August 2017–July 2018. These patients were derived from a consecutive group of 113 patients who underwent endovascular treatment for acute ischemic stroke during that time-frame with a variety of thrombectomy devices. The decision to use the Sofia (6F) PLUS catheter in the 54 included patients was at the discretion of the attending neuro-interventional radiologist.
Treatment method
The Sofia (6F) PLUS catheter was used for treatment of major vessel occlusion of the basilar arteries or the middle cerebral/internal carotid arteries distal to the origin of the posterior communicating artery. The thrombectomy method and use of adjunct thrombectomy devices was at the discretion of the attending neuro-interventional radiologist. The Sofia PLUS catheter was utilized as an intermediate or distal catheter in a triaxial system comprised of a microcatheter, the Sofia PLUS catheter, and a guide sheath in the internal or common carotid artery. The use of general anesthesia or deep sedation versus conscious sedation was determined by patient level of consciousness and surgeon’s preference. In select cases where patients were aphasic, uncooperative, or had a history of obstructive airway disease, the decision was made to intubate the patient and complete the procedure under general anesthesia.
Thrombectomy was performed by three attending neuro-interventional radiologists (DG, 15 years of experience; TM, seven years of experience; GJ, eight years of experience) using a variety of methods. In general, two basic techniques were utilized: (a) ADAPT and (b) stent retriever assisted vacuum-locked extraction (SAVE) technique involving the concurrent use of a stent-retriever and large-bore intracranial aspiration catheter (Sofia 6F PLUS).17 The universal initial steps of thrombectomy involved navigating a microwire and microcatheter past the site of thromboembolus in the occluded vessel. In cases where ADAPT was performed, the Sofia PLUS catheter was navigated distally to the proximal face of the thromboembolus, the microcatheter/microwire were withdrawn and thrombectomy was performed with direct suction using an aspiration pump.9 In stent-retriever cases, the stent retriever was deployed for a period of 3–4 min to allow for integration into the thromboembolus while suction was applied via the suction catheter using an aspiration pump. Stent-retrieval was performed with the SAVE technique in which the stent was partially withdrawn while the Sofia PLUS catheter was pushed until the two became occlusive and while maintaining suction, the stent retriever/aspiration catheter were removed as a single unit. These methods were utilized for M1 occlusions in addition to more distal occlusions involving the M2/M3 segment(s). In the case of a distal occlusion, the Sofia PLUS catheter was kept more proximal and was used in conjunction with a smaller caliber stent-retriever, which was navigated to the site of occlusion. A combination of thrombectomy techniques was used in some cases that required multiple thrombectomy passes.
Data collection/analysis
Demographic, clinical, and radiographic data were collected from inpatient records and images from digital subtraction angiograms (DSAs). The following variables were collected for each case: age, sex, past medical history, admission NIHSS score, occlusion site(s), procedural time-points spanning from time of symptom onset to revascularization, the number of thrombectomy passes, thrombectomy technique used, revised TICI revascularization grade, length of stay, inpatient mortality, discharge NIHSS, procedure- or Sofia-related complications, and long-term follow-up data including 60–90 day modified Rankin scale (MRS) score and overall mortality. MRS data were obtained at follow-up clinic visits or via telephone interview with the patient or next-of-kin. Successful revascularization was defined as TICI grades 2B, 2C, or 3. Adverse events were defined as procedure- or-Sofia-related complications such as groin hematoma, vessel dissection, distal emboli, or new intracranial hemorrhage. Statistical analysis was performed with STATA/SE (version 15 for Windows, StataCorp LLC).18 Categorical variables were expressed as frequency (percentage) and continuous variables as mean ± standard deviation or standard error.
Results
Demographic and clinical characteristics
A total of 54 patients were included in this series, equally divided between sexes (Table 1).
Table 1.
Demographic and clinical characteristics of patients (n = 54) who underwent mechanical/suction thrombectomy for treatment of major vessel occlusion using the Sofia PLUS catheter. Continuous variables presented as mean ± standard error (SE); nominal categorical variables presented as frequency (percentage); ordinal categorical data presented as median (range).
| Variables | n = 54 |
|---|---|
| Age (years) (mean, SE) | 65.30 (1.92) |
| Sex (female) | 27 (50%) |
| NIHSS | 15.98 (0.89) |
| IV tPA | 14/54 (26%) |
| Occlusion site | |
| ICA | 17/54 (31%) |
| M1 | 37/54 (50%) |
| M2 | 5/54 (9%) |
| M3 | 1/54 (2%) |
| BA | 4/54 (7%) |
| Tandem occlusions | 3/54 (6%) |
| ASPECT score | 8 (range: 5–10) |
| Collateral grading | |
| Good | 13/54 (24%) |
| Moderate | 23/54 (43%) |
| Poor | 18/54 (33%) |
| Laterality | |
| Right | 27/54 (54%) |
| Left | 23/54 (46%) |
| Medical history | |
| Hypertension | 41/54 (76%) |
| Diabetes mellitus | 12/54 (22%) |
| Hyperlipidemia | 20/54 (37%) |
| Atrial fibrillation | 16/54 (30%) |
| Smoking history | 21/54 (39%) |
ASPECT: Alberta Stroke Program Early CT; BA: basilar artery; ICA: internal carotid artery; IV tPA: intravenous tissue plasminogen activator; M1–M3: respective segments of the middle cerebral artery; NIHSS: National Institutes of Health Stroke Scale.
The mean age was 65.30 (1.92) years (range 25–89 years). The mean admission NIHSS was 15.98 (0.89). Intravenous (IV) alteplase was administered to 14 (26%) patients prior to thrombectomy. The most common occlusion site was the M1 segment of the middle cerebral artery (50%), followed by the internal carotid artery (31%), M2 segment (9%), basilar artery (7%), and M3 segment (2%). Tandem occlusions, including an occlusion of the proximal internal carotid artery/carotid bifurcation, were present in three patients (6%). Twenty-three (46%) of the anterior circulation occlusions involved the left side. Forty-one patients (76%) had a history of hypertension, 21 patients (39%) were current or former smokers, 20 patients (37%) had a history of hyperlipidemia, 16 patients (30%) had a history of atrial fibrillation and 12 patients (22%) had a history of diabetes mellitus.
Results
Revascularization
Eight patients (15%) underwent thrombectomy with an ADAPT-only method and 35 (65%) with SAVE technique. In 11 patients (20%), both ADAPT and SAVE techniques were utilized in a series of multiple thrombectomy passes (Table 2). First pass recanalization was achieved in 39% of patients. Twenty-three patients (43%) were treated with a single thrombectomy pass, 18 patients (33%) with two passes and 13 patients (24%) with three or more passes. Twenty-eight patients (52%) were treated within six hours of symptom onset. Mean arrival to groin puncture time was 62.25 (5.39) min. Mean groin to revascularization time was 42.79 (3.23) min. The average time from symptom onset to revascularization was 7.1 (0.72) h.
Table 2.
Procedural details, angiographic and clinical outcomes of patients (n = 54) who underwent mechanical/suction thrombectomy for treatment of major vessel occlusion using the Sofia (6F) PLUS catheter. Continuous variables presented as mean ± standard error; categorical variables presented as frequency (percentage).
| Procedural details/outcomes | n = 54 |
|---|---|
| Procedural timing | |
| Arrival to groin (min) | 62.25 (5.39) |
| Groin to revascularization (min) | 42.79 (3.23) |
| Arrival to revascularization (min) | 108.13 (7.30) |
| Onset to revascularization (h) | 7.10 (0.72) |
| Thrombectomy within 6 h | 28/54 (52%) |
| Thrombectomy passes (no.) | |
| 1 pass | 23/54 (43%) |
| 2 passes | 18/54 (33%) |
| ≥3 passes | 13/54 (24%) |
| First-pass recanalization | 21/54 (39%) |
| Thrombectomy methods | |
| ADAPT-only | 8/54 (15%) |
| SAVE technique | 35/54 (65%) |
| ADAPT and SAVE (multiple passes) | 11/54 (20%) |
| Sofia positioned at thrombus site | 51/54 (94%) |
| Angiographic results | |
| TICI Score | |
| TICI 0 | 6/54 (11%) |
| TICI 1 | 0/54 (0%) |
| TICI 2a | 1/54 (2%) |
| TICI 2b | 13/54 (24%) |
| TICI 2c | 6/54 (11%) |
| TICI 3 | 28/54 (52%) |
| Embolization to new territory | 0/54 (0%) |
| Complications | |
| Procedural complications | 1/54 (2%) |
| Sofia-related complications | 0/54 (0%) |
| Clinical outcomes | |
| Length of stay (days) | 9.57 (1.08) |
| Discharge NIHSS | 8.98 (1.02) |
| Inpatient mortality | 4/54 (7%) |
| Long-term outcome (60–90 days) | |
| Lost to follow-up/NR | 10/54 (19%) |
| MRS 0–2 (good) | 18/54 (41%)a |
| MRS 3–5 (poor) | 18/54 (41%)a |
| Mortality | 8/54 (18%)a |
ADAPT: direct aspiration first pass technique; MRS: modified Rankin scale; mTICI: modified thrombolysis in cerebral infarction; NIHSS: National Institutes of Health Stroke Scale; NR: not-reachable by telephone; SAVE: stent retriever assisted vacuum-locked extraction.
Percentage values refer to percentage of patients among those available for follow-up.
Forty-seven patients (87%) achieved revascularization with 28 patients (52%) of those achieving full (TICI 3) revascularization (Table 2). Positioning of the Sofia PLUS catheter in the target vessel at the site of occlusion was achieved in 94% of cases (n=51) (Figure 1). Of the three cases in which the Sofia PLUS was unsuccessfully navigated to the site of thromboembolus, two involved an M1 segment occlusion and one involved an M2 segment occlusion.
Figure 1.
Demonstrates complete M1-segment occlusion of the right middle cerebral artery (a) and subsequent complete revascularization (b) after successful distal navigation of the Sofia 6-French (6F) PLUS catheter and a single thrombectomy pass using aspiration in conjunction with a stent retriever.
Clinical outcomes
The mean length of hospital stay was 9.57 (1.08) days. The average NIHSS at time of discharge was 8.98 (1.02). One patient had transitioned to comfort measures and was deemed not testable at the time of discharge while four patients (7%) died during hospitalization. Of the 44 patients with final outcome data at 60–90 days, 41% (n = 18) had a good outcome (MRS 0–2) and 41% (n = 18) had a poor outcome (MRS 3–5). A total of eight patients (18%) were deceased at the time of final follow-up (including four inpatient deaths). One patient developed an additional stroke approximately three months following initial treatment requiring hospitalization and thrombectomy at an outside hospital. Ten of 54 patients (19%) were lost to follow-up or not reachable by telephone for interview (Table 2).
Complications
There were no procedural complications directly related to use of the Sofia PLUS catheter, such as flow-limited arterial vasospasm, arterial laceration or dissection. Overall, there was a very low procedural complication rate with one patient developing an intra-procedural neck hemorrhage from the cervical internal carotid artery during stenting for treatment of severe atherosclerotic disease-related stenosis, which required vessel sacrifice. Another patient went on to develop a complete left middle cerebral artery infarction following thrombectomy and later required a decompressive craniectomy. No patients developed vasospasm of the upper cervical and intracranial internal carotid artery.
Discussion
Several recent clinical trials have demonstrated the profound impact of mechanical thrombectomy on lowering mortality and improving clinical outcomes in select patients with acute ischemic stroke caused by large-vessel occlusion.1–7 Two recent multi-center studies have reported use of the new Sofia PLUS catheter for mechanical thrombectomy, citing high revascularization rates when used alone with ADAPT or with adjunctive thrombectomy devices such as a stent-retriever.15,16 This report adds to the overall experience with the Sofia PLUS catheter in 54 patients using a mixture of thrombectomy techniques.
The Sofia PLUS catheter’s soft/flexible tip and torquability facilitate navigation of tortuous vasculature in an expeditious fashion while theoretically minimizing the risk of endothelial injury. The versatility of the catheter provides a solid platform for distal navigation of microcatheters and deployment of stent-retrievers while also offering the capability for distal navigation of the Sofia PLUS catheter to the site of thrombus for direct aspiration. For example, in our early experience, it possible to track this catheter up to the top of the basilar artery or across tortuous segments of the cervical or cavernous internal carotid artery without inducing any vasospasm in the vessel (online Supplemental Material Video 1 and Video 2). In our series, we were able to successfully navigate the Sofia PLUS catheter to the site of thromboembolus in 94% of cases. This is consistent with the findings in previous studies, which cite successful catheter navigation in approximately 92% of cases.15,16 The overall mean time from groin access to revascularization was 42.79 (3.23) min with a mean time of 29.71 (18.44) min in patients treated with ADAPT alone. These results are comparable to the procedural timing noted in large registries or meta-analyses that cite a groin access to revascularization time of approximately 45 min.19 Similar to our series, Shallwani et al. noted a time of 28 min from groin access to first revascularization attempt.15 Our series differs from many previous studies in that our patients generally had lower rates of pre-thrombectomy alteplase use, the majority of patients were treated after six hours of stroke onset, and a large number (38%) of our patients had internal carotid artery or basilar artery occlusions that are generally associated with poorer outcomes.20,21 This finding is likely due to the fact that our study took place at a large tertiary referral center and many of the patients were transferred a great distance from neighboring community hospitals. Despite these factors, 41% of those where follow-up was available had good outcomes in this series.
According to the most recent AHA guidelines for early management of patients with acute ischemic stroke, stent-retrievers remain the first-line device for thrombectomy.8 As demonstrated in our series, the Sofia PLUS catheter can be safely used to achieve revascularization with direct suction or in conjunction with stent-retrievers while providing continuous aspiration near the site of thrombus.
The Sofia PLUS catheter has the benefit over other catheters utilized in previous studies due to its larger 6F 0.070-inch lumen, which in theory may allow for better thrombus retrieval with aspiration. In our series, we achieved an overall revascularization rate of 87% (TICI 2b/2c/3) utilizing direct aspiration and/or aspiration in conjunction with a stent-retriever. These results are consistent with those from recent reports.15 The recently reported real-world experience from the combined North American Solitaire Stent Retriever Acute Stroke (NASA) and Trevo Stent-Retriever Acute Stroke (TRACK) registry describes differing revascularization rates among 830 patients according to their time from symptom onset to treatment (0–6 h: 79.4% revascularization; 6–16 h: 72.6%; 16–24 h: 33.3%; >24 h: 33.3%; p = 0.04).20 In our series, 52% patients were treated within six hours of symptom onset and 48% after six hours of symptom onset. Our revascularization rate of 87% compares favorably with these recently published rates.
In our study, four patients (7%) died during hospitalization and one transitioned to comfort care. Although we achieved high rates of revascularization with short procedural revascularization times, approximately 41% of our patients experienced a poor outcome on 60–90 day follow-up. This finding may be related to delays in transfer from neighboring hospitals resulting in a longer duration from symptom onset to treatment and a greater proportion of internal carotid artery occlusions, which may be associated with worse outcomes.20,22 There were no procedure-related deaths or complications attributable to use of the Sofia PLUS catheter, such as catheter-induced dissection. Three patients (6%) had tandem occlusions. In all of these cases, the Sofia PLUS was successfully navigated through the internal carotid artery and thrombectomy was performed. One of these patients developed injury to the proximal cervical internal carotid artery after successful middle cerebral artery thrombectomy and during subsequent stenting for treatment of severe atherosclerotic disease-related vessel stenosis. There were no cases of clinically significant vasospasm of the upper cervical or intracranial internal carotid artery.
The limitations of our study include the retrospective design and the single-center experience making it prone to inherent bias. The small number of patients included in our study and heterogeneity of thrombectomy techniques utilized among the three attending neuro-interventional radiologists participating in the study may limit one’s ability to draw any firm conclusions from our findings. Nonetheless, we have accumulated the largest North American series published to date detailing the safe and effective use of the Sofia PLUS catheter in the treatment of acute ischemic stroke and we believe that this catheter is a welcome addition to the growing armamentarium of useful devices for thrombectomy.
Conclusion
The Sofia PLUS catheter can be safely used to quickly achieve revascularization in patients undergoing thrombectomy for treatment of acute ischemic stroke. The Sofia PLUS catheter may be employed as a distal access catheter and/or direct suction catheter in order to achieve revascularization using a variety of thrombectomy techniques. Our initial experience with this catheter has been encouraging. Future studies, in the form of multi-center registries or randomized clinical trials, are warranted in order to further evaluate the comparative safety and efficacy of the Sofia PLUS catheter.
Acknowledgements
The following author contributions were made: AP Wessell – study design/conception, data acquisition/analysis, drafting, revising and final approval of manuscript; G Cannarsa – data acquisition/analysis, drafting, revising and final approval of manuscript; H Carvalho – data acquisition/analysis, final approval of manuscript; MJ Kole – data acquisition/analysis, final approval of manuscript; P Sharma – data acquisition/analysis, final approval of manuscript; EJ Le – data acquisition/analysis, final approval of manuscript; G Jindal – study design/conception, drafting, revising and final approval of manuscript; TR Miller – study design/conception, drafting, revising and final approval of manuscript; D Gandhi – study design/conception, drafting, revising and final approval of manuscript.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conflict of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Supplemental material
Supplemental material for this article is available online.
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