5.1.1 Clinical Presentation

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  A 37-year-old female presented to the emergency department approximately 30 minutes after acute onset of left-sided hemiplegia.

  
  
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  Clinical examination revealed severe dysarthria, hemiplegia of the left side, and neglect to the left side (National Institutes of Health Stroke Scale [NIHSS] score of 18).

5.1.2 Imaging and Workup

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  Noncontrast CT demonstrated dense middle cerebral artery (MCA) sign on the right side.

  
  
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  CT angiography showed right internal carotid artery (ICA) occlusion consistent with dissection and right MCA occlusion.

  
  
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  MRI confirmed the ICA dissection and demonstrated restricted diffusion limited to the lenticulostriate distribution of the MCA.

5.1.3 Diagnosis

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  Right ICA occlusion consistent with dissection and right MCA occlusion.

  
  
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  She was given intravenous tissue plasminogen activator IV-tPA 1 hour 10 minutes after symptom onset; however, the patient continued to display persistent left hemiplegia with no clinical improvement.

  
  
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  After interdisciplinary discussion, the decision was made for mechanical thrombectomy of the occluded M1 segment.

5.1.4 Technique

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  The procedure was performed under conscious sedation. The patient was prepped and draped in the usual sterile fashion. The right common femoral artery was localized by ultrasound and palpation. A right common femoral artery puncture was performed. An 8-Fr short arterial sheath was placed.

  
  
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  An 8-Fr MERCI Balloon guide catheter was then prepared. Using a coaxial technique with a 5-Fr, 125-cm HH1 catheter and a Terumo glide wire, the 8-Fr balloon guide catheter was advanced into the right common carotid artery. Injection of the right common carotid artery confirmed occlusion of the right ICA just above the bifurcation, with flame-shaped tapering in keeping with an internal carotid dissection.

  
  
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  Using road map technique, the Terumo glide wire was carefully advanced beyond the occlusion, taking care to remain within the true lumen of the vessel. The HH1 and 8-Fr Balloon guide catheters were then advanced into the right ICA, to about the C2–C3 level.

  
  
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  Angiography performed through the guide now showed the intracranial ICA. The carotid termination and the right A1 segment were patent. The right M1 segment was occluded proximally. There were some late leptomeningeal collaterals (poor). Following injection, there was stasis of contrast in the ICA, in keeping with the proximal ICA occlusion.

  
  
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  A Rebar 18 microcatheter was prepared, and attached to a flush system. Using roadmap technique, the microcatheter was navigated along with the Transend Soft Tip Guidewire into the upper M2 trunk of the right MCA.

  
  
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  A Solitaire 5 mm × 40 cm stent retriever device was placed across the MCA clot, from the M2 upper trunk to the supraclinoid ICA, and it was unsheathed to deploy. With stent deployment, antegrade flow was seen in the right MCA. The stent was left in position for 5 minutes, and then retrieved. The balloon was not inflated on the guide, as the dissection of the ICA was already occluding the ICA. Continuous suction was applied to the balloon guide during stent retrieval. Thrombus was observed on the retrieved stent. The guiding catheter and hub were meticulously aspirated and flushed. Postretrieval hand and pump injections showed good patency of the M1 segment of the MCA and most M2 branches. The ACA remained patent, with flash filling. There was still ICA stasis in keeping with the proximal occlusion (Fig. 5.1).

  
  
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  Attention was then turned to the proximal ICA dissection. The guide catheter was carefully withdrawn into the common carotid artery. A hand injection of contrast showed irregularity of the ICA at the site of prior dissection, with less than 50% luminal narrowing and no evidence of hemodynamic compromise. The possibility of stenting to preserve the proximal ICA patency was discussed with neurology. It was agreed not to stent to avoid use of aspirin and Plavix.

  
  
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  A repeat common carotid angiogram was performed after a 15-minute delay. The MCA remained patent. The ICA had improved in appearance, with less narrowing than on the previous angiogram.

  
  
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  At this point, it was decided to terminate the procedure. The guiding catheter was removed. The 8-Fr groin sheath was sewn in place. On the day following the procedure, the groin sheath was removed and manual compression for about 30 to 40 minutes gave good hemostasis. The patient had a dramatic improvement in right arm and leg motor function following the procedure.

  

5.1.5 Outcome

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  Recanalization of right MCA occlusion using Solitaire stent retriever device was technically successful.

  
  
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  Patient also had an occlusive dissection of the proximal right ICA as seen on the CTA prior to procedure. Following placement of the large guide catheter across the dissection into the distal true lumen, and subsequent retrieval of the catheter into the CCA, the proximal ICA was recanalized and remained patent without evidence of hemodynamic compromise.

  
  
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  Early neurological improvement was noted after the procedure. At discharge 7 days later, the NIHSS score was 2, and she made an excellent functional recovery.

5.1.6 Discussion

After publication of the positive trials in 2015, many systematic reviews and meta-analyses sought to pool together the data from these trials to make a more robust claim for mechanical thrombectomy. Four meta-analyses were published in 2016 that used a variety of methods to pool together patient data and perform further analyses across the RCTs.

The first of these meta-analyses was published in November 2015 in JAMA. This meta-analysis included eight RCTs with published results at the time: IMS III, SYNTHESIS, MR RESCUE, MR CLEAN, ESCAPE, EXTEND-IA, SWIFT-PRIME, and REVASCAT. A total of 2,423 patients were included, with 1,313 who received endovascular therapy and 1,110 who received standard medical treatment. The study discovered that endovascular therapy was associated with an improvement of modified Rankin scale (mRS) scores (odds ratio [OR]: 1.56, 95% confidence interval [CI]: 1.14–2.13). Moreover, 12% more patients in the endovascular group achieved functional independence (mRS ≤2) at 90 days (OR: 1.71, 95% CI: 1.18–2.49). There were also significantly higher rates of revascularization achieved with endovascular thrombectomy (75.8%) than tPA alone (34.1%; OR: 6.49, 95% CI: 4.79–8.79). There were no differences in symptomatic intracerebral hemorrhage (SICH) or all-cause mortality at 90 days. However, the heterogeneity between the studies was high for the mRS. Thus, subgroup and sensitivity analyses were performed. In particular, functional outcomes were significantly better in patients with confirmed proximal artery occlusions on imaging, those who received a combination therapy of both endovascular and tPA, and those who received the stent retrievers. In addition, there was interaction between the study year and functional outcomes in that, unsurprisingly, the older trials revealed less effect sizes. This meta-analysis synthesized the results from multiple RCTs, and despite the presence of heterogeneity among the trials, endovascular therapy was still shown to result in better functional outcomes and better revascularization rates when compared with standard medical management. ¹

Another meta-analysis was published in Stroke in March 2016, and it included patient-level data from ESCAPE, SWIFT PRIME, EXTEND-IA, and REVASCAT, RCTs that primarily used the Solitaire device. The primary analysis included 787 patients from all four trials, of which 401 were randomized to endovascular group and 386 to the standard medical therapy. The primary outcome was functional score at 90 days as defined by the mRS. Secondary outcomes were functional independence (mRS ≤2), mortality, and SICH rates. In the primary analysis, the common odds ratio (cOR) for mRS improvement was 2.7 (95% CI: 2.0–3.5). The number needed to treat (NNT) to reduce disability was 2.5 and the NNT for a better independent functional outcome was 4.25. Mortality and SICH rates were not significant. Two sensitivity analyses were performed as well, excluding patients in whom Solitaire was not the first device used and excluding ESCAPE where other devices were allowed. The results of these sensitivity analyses were similar to the primary analysis. The benefit of thrombectomy was consistently observed in all predefined subgroups, regardless of age, sex, NIHSS score, the site of lesion, presence of tandem cervical carotid occlusions, ASPECTS score, and administration of IV-tPA. Furthermore, though older age is frequently an exclusion criterion for thrombectomy, the result from this meta-analysis suggests that there is no evidence of reduced benefit in the elderly patient (≥80 years of age). In fact, there was an observed clinically significant 20% absolute reduction in mortality rates. Moreover, in IMS III and MR CLEAN, NIHSS was a selection criterion for patients. This meta-analysis found no significant difference in benefit in patients with NIHSS ≤ 15 in comparison to patients with NIHSS > 20. Lastly, the pool data affirmed that better functional outcome is achieved with decreased time from onset to intervention. The result from this meta-analysis suggests that the Solitaire device is safe and effective in treating large vessel occlusions, leading to improvement in functional outcome and reduced disability in all patient subgroups. ²

A systematic review published in the BMJ was conducted by researchers in Portugal. This study included all RCTs comparing medical care with endovascular therapy. All of the 2,925 patients from 10 studies were included, those from IMS III, SYNTHESIS, MR RESCUE, MR CLEAN, ESCAPE, EXTEND-IA, SWIFT-PRIME, REVASCAT, THERAPY, and THRACE. With the pool analysis, endovascular treatment had higher proportion of patients with good or excellent functional outcomes (mRS ≤ 2 or 1). The risk ratio of a good functional outcome was 1.37 (95% CI: 1.14–1.64). Mortality and SICH rates were not significant. However, heterogeneity of the studies was high. After excluding the 2013 trials, MR RESCUE, SYNTHESIS, and IMS III, there were no longer heterogeneity among the trial results, and the risk ratio of a good functional increased to 1.56 (95% CI: 1.38–1.75). Due to methodological issues with MR RESCUE, SYNTHESIS, and IMS III, the OR of 1.56 was deemed to be a more accurate reflection of endovascular therapy’s true effect. This systematic review provided moderate- to high-quality evidence that endovascular therapy 6 to 8 hours after acute ischemic stroke onset provides benefit in functional outcomes. ³

The final meta-analysis included data only from the five RCTs published in 2015: MR CLEAN, ESCAPE, EXTEND-IA, SWIFT-PRIME, and REVASCAT. This meta-analysis was published in the Lancet, and included data from 1,287 patients with 634 randomized to endovascular thrombectomy and 653 to medical therapy. The pooled results indicate that endovascular treatment was associated with significant reduction of disability, as measured by mRS, at 90 days (adjusted cOR: 2.49, 95% CI: 1.76–3.53). Moreover, the NNT to reduce at least one score of mRS was 2.6. Mortality and SICH rates did not differ between the intervention and control groups. There were many subgroups of clinical interest associated with a significant effect favoring endovascular thrombectomy. In particular, patients older than 80 years achieved a cOR of 3.68 (95% CI: 1.95–6.92) favoring the intervention. Patients who were randomized 300 minutes after onset of symptoms achieved cOR of 1.79 (95% CI: 1.05–2.97). Patients who were not eligible for IV-tPA had cOR of 2.43 (95% CI: 1.30–4.55). This result shows benefit for patients who are older, those who underwent randomization later, and those in which IV-tPA was contraindicated. ^{4 ,​ 5 ,​ 6}

With these systematic reviews and meta-analysis, it is more evident than ever that endovascular thrombectomy is more effective than tPA alone in treating patients with acute ischemic strokes. The functional outcome was better with intervention even with patient data included from the negative 2013 trials. When results from only the newer trials were analyzed, the effect size was considerably larger. There was also new evidence that the intervention is effective regardless of patient age, NIHSS score, ASPECTS score, site of lesion, presence of tandem cervical carotid occlusions, whether concomitant tPA was administered, and whether randomization was delayed. ^{2 ,​ 3 ,​ 4} Essentially, endovascular therapy is safe and effective in almost all patient groups. With the current solid evidence, endovascular therapy should be the standard of care for large artery occlusions in the anterior circulation. Policy makers around the world have since been urged by investigators to put a greater emphasis on building health care systems that increase the accessibility of advanced stroke services to the population.