Switching Strategy for Mechanical Thrombectomy of Acute Large Vessel Occlusion in the Anterior Circulation
Background and Purpose—We introduce the concept of a switching strategy for mechanical thrombectomy with period-to-period analysis. In period 1, forced arterial suction thrombectomy with a Penumbra reperfusion catheter was performed, even in difficult cases; in period 2, forced arterial suction thrombectomy was initially performed, with switching to Solitaire in difficult cases.
Methods—We analyzed 135 consecutive patients treated with mechanical thrombectomy with acute large vessel occlusion in the anterior circulation, 61 from period 1 and 74 from period 2. We defined difficult case for both periods as ≥3 failed attempts at recanalization.
Results—Period 2 showed a trend for better angiographic outcome of Thrombolysis in Cerebral Infarction 2b-3 (73.8%, period 1 versus 85.1%, period 2; P=0.10). In interperiod subgroup analysis of difficult cases, switching significantly outperformed nonswitching in Thrombolysis in Cerebral Infarction 2b-3 recanalization (52.7% versus 82.9%; P=0.030). Differences in puncture-to-recanalization time, symptomatic intracranial hemorrhage incidence, and procedure-related complications were not statistically significant.
Conclusions—A switching strategy using 2 mechanical thrombectomy techniques (forced arterial suction thrombectomy to Solitaire) may harbor better angiographic outcomes than a 1 technique only strategy (forced arterial suction thrombectomy).
Regarding mechanical thrombectomy (MT) for acute ischemic stroke, there are several available techniques, each offering different advantages.1 We hypothesized that applying a different MT technique when 1 failed could improve recanalization because the occlusion might harbor various circumstances.
Among the MT techniques,1 we used 2. Forced arterial suction thrombectomy (FAST) with the Penumbra reperfusion catheter2 was primarily used. Once the Solitaire stent (Covidien/ev3, Dublin, Ireland) became available, Solitaire thrombectomy followed FAST in difficult cases.
This study aimed to describe the efficacy and safety of the aforementioned switching strategy by comparing procedure time, angiographic outcome (Thrombolysis in Cerebral Infarction), rate of procedure-related complications, and intracranial hemorrhage (ICH) between 2 treatment periods (period 1: FAST only; period 2: switching from FAST to Solitaire in difficult cases).
The subjects were retrospectively selected from a prospectively maintained registry. Inclusion criteria for MT were as follows: (1) acute ischemic stroke attributable to large vessel occlusion in the anterior circulation on time-of-flight magnetic resonance angiography or computed tomographic angiography and (2) the extent of infarct volume on diffusion-weighted imaging or computed tomography was less than one half of the affected vascular territory. The local institutional review board approved this study for retrospective analysis.
Treatment Algorithm and Assessment
After inspection of the treatable occlusion with diagnostic angiography, MT was initiated under local or general anesthesia. We defined difficult case as unsuccessful recanalization after 3 attempts of FAST in 1 segment of an occlusion. In period 1 (from April 2009 to October 2010), we always used FAST, even in difficult cases, calling the subgroup difficult nonswitching. In period 2 (from October 2010 to January 2012), we attempted FAST first in all cases, but switched to Solitaire thrombectomy in difficult cases, and we called this subgroup difficult switching (Figure). Techniques for FAST and Solitaire thrombectomy are the same as described previously.2,3
The onset of the stroke was defined as the time when the patient was last seen normal. Recanalization was measured by the Thrombolysis in Cerebral Infarction scale and was regarded as successful if Thrombolysis in Cerebral Infarction 2b-3 was achieved in the final angiography. Symptomatic ICH was defined as any type of hemorrhage associated with an increase in the National Institutes of Health Stroke Scale score of ≥4 within 24 hours.3
Statistical analysis was performed using the SPSS statistical package (SPSS for Windows, version 20.0, Chicago, IL). The χ2, Student t, and Mann–Whitney U tests were used for comparisons as appropriate.
One hundred thirty-five consecutive patients with a large vessel occlusion in the anterior circulation were treated with MT and were included in the analysis (Tables 1 and 2). There were 61 patients in period 1 and 74 in period 2. No clinically relevant differences were found in the baseline characteristics between the 2 groups, with the exception of age, baseline National Institutes of Health Stroke Scale score, and door-to-puncture time.
The median puncture-to-recanalization time in each period was 60 and 68 minutes, respectively (P=0.485). Successful recanalization was achieved in 45 of 61 patients in period 1 and 63 of 74 in period 2, and there was a trend for better recanalization in period 2 (73.8% versus 85.1%; P=0.10). Procedure-related complications occurred in 8 of 135 cases, which included subarachnoid hemorrhage associated with the dissection of the occluded vessels in 7 cases (4 cases during FAST and 3 during Solitaire thrombectomy) and captured clot migration to the contralateral anterior cerebral artery in 1 case, but there were no statistically significant differences between 2 groups. Symptomatic ICH occurred in 6.7% (n=9) of patients, but interperiod differences were not statistically significant.
In the subgroup analysis between difficult nonswitching and difficult switching, there were significant differences in rates of successful recanalization (57.7% versus 82.9%; P=0.030) and insignificant differences in puncture-to-recanalization time, symptomatic ICH, and procedure-related complications.
One patient received intra-arterial urokinase (a dose of 70 000 U) to recanalize the M1 occlusion. Determinants of successful recanalization within 3 attempts of FAST, interval angiographic changes, distal embolization results, and procedure-related/hemorrhagic complications are described in detail in Tables I, II, III and IV in the online-only Data Supplement.
There are several MT techniques with different concepts and features.1 For example, thrombus aspiration and proximal thrombectomy (FAST in this article) is technically simple, fast to apply, and inexpensive.1,2,4 In terms of stent retrievers such as Solitaire FR and Trevo (Stryker, Mountain view, CA), several benefits include immediate revascularization after stent deployment, easy advancement, and a high recanalization rate.3,5
During period 1, we experienced cases of difficult recanalization or failure using only FAST; therefore, we switched techniques in difficult cases during period 2 under the hypothesis that additional attempts of MT with a different mechanism (Solitaire) could improve recanalization. This study highlights the role of switching strategy with comparing outcomes between 2 study periods using different MT protocols.
The main findings were the following: (1) although puncture-to-recanalization times were not significantly different, there was a trend of higher successful recanalization during period 2; (2) successful recanalization differences were more pronounced in the subgroup analysis between difficult nonswitching and difficult switching cases, which may suggest switching MT techniques in difficult cases can increase the chances of better recanalization; and (3) the switching strategy did not increase procedure-related complications or incidence of ICH.
This study has several potential limitations. First, although the patients were enrolled prospectively, the data were analyzed retrospectively. Consequently, the treatment groups were not randomized and concurrent. Also, a negative impact on outcomes related to somewhat longer time variables (picture-to-puncture, door-to-puncture, and puncture-to-recanalization) could not be excluded. Second, there was a baseline imbalance for age, baseline National Institutes of Health Stroke Scale, and door-to-puncture time between the 2 periods. Period 2 showed better outcome data despite harboring worse baseline conditions, including significantly elder patients and higher baseline National Institutes of Health Stroke Scale score. On the contrary, door-to-puncture time was significantly reduced in period 2, which might have resulted from increasing experience at the system level. Therefore, we could not exclude the possibility that this imbalance influenced the outcome. Third, our study solely used 0.041- or 0.054-in Penumbra aspiration catheters (Penumbra, Alameda, CA) during FAST; thus, different outcomes may have resulted, if larger catheters were applied.4 Finally, this study only contains switching techniques from FAST to Solitaire thrombectomy, and the data should be interpreted cautiously because different types of switching may result in different outcomes.
The present study comparing 2 strategies for MT in patients with similar baseline characteristics indicates that switching techniques in difficult cases (FAST to Solitaire) may harbor better angiographic outcomes than universally committing to 1 technique (FAST) for acute large vessel occlusion in the anterior circulation. However, these findings should be interpreted cautiously because of the aforementioned limitations, and confirmation by prospective multicenter trials is necessary.
We thank Wade Martin of Medical Research International for his critical English revision.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.113.002673/-/DC1.
- Received June 30, 2013.
- Accepted August 13, 2013.
- © 2013 American Heart Association, Inc.
- Gralla J,
- Brekenfeld C,
- Mordasini P,
- Schroth G
- Kang DH,
- Hwang YH,
- Kim YS,
- Park J,
- Kwon O,
- Jung C
- Jankowitz B,
- Aghaebrahim A,
- Zirra A,
- Spataru O,
- Zaidi S,
- Jumaa M,
- et al