Comparison of the Solitaire and Trevo Stents for Endovascular Treatment of Acute Ischemic Stroke: A Single.Center Experience
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.314580
Source of Support: None, Conflict of Interest: None
Keywords: Stent, stentriever, stroke, thrombectomyKey messages: Trevo stent has several advantages over Solitaire stent in EVT for AIS patients. However, these advantages do not have a significant influence on good clinical outcomes.
Since the Solitaire stent (EV3 Inc., Irvine, CA, USA; referred to hereafter as Solitaire) was first used for thrombectomy in acute ischemic stroke (AIS) in 2008, stent-based thrombectomy has been widely used for stroke caused by large artery occlusion. Stent thrombectomy has been shown to achieve higher recanalization rates than nonstent thrombectomy for AIS, and it has been associated with improved clinical and radiographic outcomes and safety. In 2015, randomized, controlled studies for AIS with large artery occlusion showed that endovascular thrombectomy (EVT) using stentrievers improved functional outcomes,,,,, and the benefit of EVT appeared to be consistent across trials. Moreover, the 2015 focused update of the American Heart Association/American Stroke Association recommended that EVT using stentrievers for patients with AIS and large vessel occlusion should be considered preferentially.
Currently, Solitaire is the most commonly used and successful stentriever in randomized, controlled trials, and it is the most represented stentriever for thrombectomy. Recently, various types of thrombectomy stents have been developed to achieve better recanalization rates and safety, one of which is the Trevo retriever (Stryker Neurovascular/Concentric Medical, Mountain View, CA, USA; referred to hereafter as Trevo).
Trevo is a retractable stent developed specifically for EVT; it was designed for better removal of the thrombus in AIS via integration in the clot. A previous study showed that Trevo resulted in thrombolysis in cerebral infarction (TICI) grade 2 or greater, and reperfusion rate of 86%, and was associated with improved clinical outcomes.
Advances in thrombectomy technology affect clinical outcomes; therefore, advances in stentrievers are also expected to lead to better clinical outcomes. However, only a few studies have compared different retrievable stents. In this study, we aimed to compare the safety and efficacy of Solitaire and Trevo for EVT of patients with anterior circulation AIS.
Study population and patient selection
This was a single-center, retrospective, registry-based study approved by the institutional review board (2018-03-05). All patients suspected of having AIS were evaluated with angiography and perfusion imaging, according to the hospital's AIS evaluation protocol. Patients initially underwent magnetic resonance (MR)-based evaluations. When MR-based evaluations were not available, computed tomography (CT)-based assessments were performed. Several reports have shown that ischemic penumbra can exist up to 24-48 h after stroke onset., If perfusion images showed significant diffusion-perfusion mismatch up to 24 h after stroke onset, then we attempted EVT. Written informed consent was obtained from each patient before the procedure.
This study used a prospectively collected stroke registry to identify 167 patients with anterior circulation AIS who underwent EVT between January 2013 and April 2016. Among them, 130 patients who had symptom onset within 24 h and underwent EVT with either Solitaire or Trevo were included in this study. All included patients exhibited proximal artery occlusion and significant diffusion-perfusion mismatch more than 200%.
Endovascular thrombectomy procedure and follow-up imaging evaluation protocol
Intravenous recombinant tissue plasminogen activator (IV-rtPA) was administered on arrival for each patient within a specific time window, and EVT was performed as bridging therapy when large vessel occlusion and diffusion-perfusion mismatch were found.
Before 2014, Solitaire was the only stent used for EVT. In 2014, Trevo stents also became available for EVT. All procedures were performed by one neurointerventionist, and the neurointerventionist who performed the procedure determined which stentriever has to be used for each EVT by operator's discretion. EVT was conducted utilizing one of the following coaxial guiding catheters: 9-F balloon guiding catheter, 6-F guiding catheter, or distal access catheter. After the guiding system located the proximal internal carotid artery, the microcatheter was navigated through the occluded segment of the artery, and the stentriever was positioned through the microcatheter to the site of the thrombus and deployed. The stent was left in place for up to 3–5 min. When the stentriever retrieved the clot, balloon inflation of the balloon guiding catheter was performed to arrest the antegrade flow from the carotid artery. After the stentriever retrieved the clot, aspiration was performed through the guiding or distal access catheter to capture fragmented and remaining clots in the carotid artery. The same procedure was repeated until recanalization was achieved. If successful recanalization was not achieved, then rescue treatment was performed in an effort to achieve successful recanalization.
CT was performed immediately after EVT to screen for hemorrhagic complications, and diffusion-weighted imaging (DWI)-MR scans were performed 24 h after EVT to detect any thromboembolic complication and to confirm the progression of the lesion. Magnetic resonance angiography (MRA) was performed 1 week later to evaluate patency of the recanalized vessel.
Variables and outcome measures
Our data included baseline characteristics, procedural outcomes, procedural safety outcomes, and clinical outcomes. Baseline characteristics included age, sex, median National Institutes of Health Stroke Scale (NIHSS) score at admission, the use of IV-rtPA as a bridging therapy, location of occlusion, concomitant proximal internal carotid artery (ICA) occlusion, time frames from symptom onset to arrival and from arrival to puncture time, and presence of vascular risk factors. Procedural outcomes consisted of successful recanalization after the first pass, clot retrieval rate, rate of the use of another method, final angiographic outcome after EVT, and time from a puncture to recanalization. Safety outcomes included asymptomatic hemorrhage, symptomatic hemorrhage, and thromboembolism during and after EVT. Clinical outcomes were assessed after 3 months.
Regarding safety outcomes, hemorrhagic complications included hemorrhagic transformation, intracerebral hemorrhage, subarachnoid hemorrhage, and thromboembolism. Among these, symptomatic hemorrhage was defined as an increase in NIHSS score of ≥4 points or requiring intervention. A thromboembolic complication was defined as occlusion of the distal part of the lesion or occlusion of a new lesion that was completely different from the original lesion observed with angiography performed after EVT.
Primary clinical outcome measures included the modified Rankin Scale (mRS) score at 3 months and recanalization rate assessed using TICI grades. A good and poor clinical outcome was defined as mRS score ≤2 or ≥3, respectively, at 3 months. Successful recanalization was defined as a TICI grade of 2b or 3.
Patients were analyzed based on the stent used for EVT. Between-group (Solitaire vs. Trevo) analyses were performed to compare baseline patient characteristics, procedural outcomes, complications, and clinical outcomes. Statistical analysis for each outcome variable was performed using SPSS software version 20 (IBM Software, Chicago, IL, USA). An unpaired t-test, χ2 test, and Fisher's exact test were used as appropriate. P ≤ 0.05 was considered statistically significant.
Among the 130 patients with AIS who underwent EVT and were included in this study, 79 were treated with Solitaire and 51 were treated with Trevo. Patients treated with Solitaire had a mean age of 69 years (range, 38–92 years) and a median NIHSS score of 15 (interquartile range, 12–19) at admission; 44 were women. Patients treated with Trevo had a mean age of 67 years (range, 25–88 years) and a median NIHSS score of 14 (interquartile range, 11–17) at admission; 25 were women.
Age, sex, median NIHSS score at admission, the use of IV-rtPA as a bridging therapy, occlusion location, and concomitant proximal ICA occlusion were similar between groups. In addition, the time frames from symptom onset to arrival and from arrival to puncture time were different between groups; however, this difference was not statistically significant. Comparable vascular risk factors, including the presence of hypertension, diabetes, atrial fibrillation, previous cerebrovascular accident, and coronary artery disease, were not statistically significant between groups [Table 1].
The majority of procedural outcomes were significantly different between groups. A good recanalization rate with a TICI grade of 2b or 3 after the first pass and the clot retrieval rate were higher in the Trevo group but these differences were not significantly different between the groups. However, the frequency of adjuvant thrombolytic or other mechanical rescue treatment use (also known as rescue treatments) was higher in the Solitaire group (n = 47) than in the Trevo group (n = 16) (P < 0.001). Final good recanalization rates were significantly higher in the Trevo group (n = 46; 90.2%) than in the Solitaire group (n = 57; 72.2%) (P = 0.01). Furthermore, the time from a puncture to recanalization was significantly shorter in the Trevo group (51 min) than in the Solitaire group (88 min) (P < 0.001) [Table 2].
The incidence rates of asymptomatic hemorrhage, symptomatic hemorrhage, and thromboembolism were not significantly different between groups [Table 3].
Good clinical outcomes (mRS score, 0–2) were more frequently observed in the Trevo group than in the Solitaire group. However, good clinical outcomes were not statistically different between groups (P = 0.16). There was no statistically significant difference in mortality at 3-month follow-up (P = 0.20) but a relatively increased incidence was noted in the Solitaire group (11.4%) compared with the Trevo group (3.9%) [Figure 1].
The development of newer mechanical thrombectomy devices has offered improved recanalization and safety profiles and has resulted in superior recanalization for stroke therapy. Notably, stentrievers such as Solitaire and Trevo, have demonstrated markedly improved recanalization rates compared to their earlier counterparts. Solitaire was originally developed for the treatment of wide-neck aneurysms. However, since its first use for the treatment of AIS in March 2008, Solitaire has been used as a main stentriever in recent large-scale, randomized, controlled trials, resulting in excellent outcomes.,,,,,,,,,, In addition, previous studies have shown that the use of Solitaire has led to good results compared to the use of IV-rtPA alone for procedural outcomes, clinical outcomes, and complications., However, Solitaire was not developed as a device for EVT, even though it is used more often for EVT for AIS. In contrast, Trevo was originally developed and used for EVT, and its use has resulted in excellent EVT outcomes comparable with those of Solitaire.,,,, There are few studies that have directly compared the two products. However, Mendonçja et al. and Walcott et al. have suggested that the use of both Solitaire and Trevo could achieve relatively high recanalization rates.,
In the current study, there were no statistically significant differences between groups regarding the patients' baseline characteristics [Table 1]. However, there were some statistically significant between-group differences for procedural and clinical outcomes. For example, the frequency of rescue treatment use was significantly lower when Trevo was used. The final good recanalization rate was significantly higher and the puncture to recanalization time was significantly shorter in the Trevo group than in the Solitaire group. However, regarding clinical outcomes, there were no significant differences in good outcomes between groups (mRS score, 0–2).
These results could be explained by the differences in the stent designs. For example, Solitaire is a self-expanding stent that has the unique capability of being fully deployed and then completely retrieved if it has not been detached.,, Conversely, Trevo is a novel embolectomy device that was specifically designed to remove the thrombus in AIS, and it aims to integrate the clot into the stent structure to allow the user to retract the device and clot from the blood vessel., To achieve this goal, Trevo has a vertical stent strut design with a larger area, resulting in the improved ability to capture the thrombus.
Furthermore, the Trevo group tended to have a higher clot retrieval rate. In addition, the difference in stent design likely contributed to the Trevo group requiring the use of rescue treatments less often and requiring less time for recanalization after the puncture, resulting in higher final good recanalization rates through improved capture and retrieval of the thrombus.
According to the sub-analysis of the multicenter, randomized, clinical trial of endovascular treatment for acute ischemic stroke in the Netherlands (MR CLEAN), there were no differences in the effects of thrombectomy for AIS according to the type of stent. This result agrees with a recent systematic review of the effects of thrombectomy according to stent type that also showed no significant differences between studies that used Trevo and studies that used Solitaire. Several aspects of this study were similar to those of previous studies. Compared with a previous head-to-head study of the two stents, this study used a larger sample size. In addition, the final good recanalization rate of the Solitaire group in this study was similar to that of a previous study. Therefore, we think that the better recanalization rate and other results shown in the Trevo group were due to the characteristics of the Trevo stentriever. Finally, the baseline characteristics of the groups regarding stroke severity and occlusion location were not significantly different, despite this being a single-center study.
There were two major limitations to our study. As mentioned, this was a small single-center study. Furthermore, the devices were not randomly assigned; instead, they were assigned based on the discretion of the practitioners. Since this was a single-center study, the results should be interpreted cautiously. However, because this is the first study to show differences between these stentrievers, the results may help neurointerventionists to decide which commercially available products to use.
In conclusion, this study showed that patients who performed EVT with Trevo stents for AIS had a higher recanalization rate, less use of rescue treatment, and less time for recanalization than patients with Solitaire stents but no significant difference in good outcome (mRS 0–2).
[Table 1], [Table 2], [Table 3]