Aspiration Thrombectomy in Patients with Large Vessel Occlusion and Mild Stroke: A Single-Center Experience

Background

The endovascular approach is recommended nowadays for the treatment of patients suffering from acute ischemic stroke (AIS) due to intracranial large vessel occlusion (LVO). According to the AHA/ASA 2018 guidelines, mechanical thrombectomy using stent retrievers is recommended for AIS patients when procedure initiation is within 6 h of symptoms onset. Patients should also have pre-stroke modified Rankin scale (mRs) score <1, Alberta Stroke Program Early Computed Tomography score >6, or National Institutes of Health Stroke Scale (NIHSS) score >6, and causative occlusion of the internal carotid artery or proximal middle cerebral artery (MCA) [1]. Treatment of ischemic stroke due to LVO and mild stroke with NIHSS score <6 represents a particular challenge, since the potential risk of thrombectomy must be weighed against the potential disability caused by neurological deterioration. Few studies have reported outcomes of patients with NIHSS scores <6 treated with mechanical thrombectomy [2–6]. In the ESO-ESMINT 2019 Guidelines on Mechanical Thrombectomy in Acute Ischemic Stroke, most experts (9/11) suggested that, for patients with low NIHSS scores (0–5) who are not eligible for a dedicated randomized controlled trial, treatment with mechanical thrombectomy in addition to intravenous thrombolysis (or alone in cases where intravenous thrombolysis is contraindicated) may be reasonable if the patient has clearly disabling deficits (eg, significant motor deficits, aphasia, or hemianopia) at presentation, or if clinical symptoms worsen despite intravenous thrombolysis [7]. The purpose of this study was to evaluate immediate aspiration thrombectomy in patients suffering from mild strokes, defined by an NIHSS score <6, caused by LVO.

Material and Methods

STATISTICAL ANALYSIS:

Continuous variables were calculated as median (interquartile range, IQR) or as mean±standard deviation (SD). Categorical variables are reported as proportions. P-values were calculated using Fisher’s exact test for categorical variables, the Mann-Whitney U test (Wilcoxon rank-sum test) for non-normally distributed continuous variables and Welch’s t test for normally distributed continuous variables.

Results

We identified 27 patients with NIHSS scores <6 who underwent endovascular thrombectomy and were included in the analysis. The mean age was 69.8±12.3 years and 40.7% were male. Twenty-five patients (92.6%) had a pre-stroke mRs score 0–1 and 2 patients (7.4%) had an mRs score >2. The median baseline NIHSS score was 4 (2–5). Seven patients (25.9%) were taking antithrombotics and 1 patient (3.7%) was receiving anticoagulation therapy before the stroke onset. Seventeen patients (63%) were treated in the vicinity of the endovascular center (the “mothership” concept) and 10 patients (37%) came from primary stroke centers (the “drip-and-ship” concept). The risk factors for stroke and etiology are presented in Table 1. Radiological findings, logistics, and outcome measures are summarized in Tables 2 and 3. In patients with anterior stroke, 9 patients (33.3%) had M2 MCA occlusion, 6 patients (22.2%) had M1 MCA occlusion, 3 patients (11.1%) had tandem occlusions, and 1 patient (3.7%) had a carotid T occlusion. Eight patients (29.6%) suffered from posterior stroke, 3 patients (11.1%) had occlusions localized in the basilar artery, and 5 patients (18.5%) had occlusions in the posterior cerebral artery. Immediate direct aspiration “ADAPT” was used in 25 patients (92.6%) and rescue therapy aspiration together with stent-retriever thrombectomy was necessary in 2 patients (7.4%). Periprocedural extracranial carotid artery stenting was performed in 2 patients (7.4%). None of the patients suffered early reocclusion of the treated vessel or stroke in other vascular territory within 7 days. The mean number of catheter maneuvers in the target vessel was 1.4±0.6. TICI recanalization scores of 2b or 3 were reached in 25 patients (92.6%); no periprocedural complications were observed either at the site of approach or intracranially. Sixteen patients (59.3%) had TICI recanalization scores of 2b or 3 following a single first pass in the target vessel using ADAPT. At 3-month follow-up, 21 patients (77.8%) had a good functional outcome, with an mRs score of 0–2, and 18 patients (66.7%) had an excellent clinical outcome, with an mRs score of 0–1. Only 1 patient (3.7%) had a symptomatic intracranial hemorrhage, as defined by the ECASS 3 criteria. Two patients (7.4%) died.

Nineteen occlusions (70.4%) were localized in the anterior circulation and 8 (29.6%) were localized in the posterior circulation. There were no statistically significant differences in observed parameters, except for a history of stroke in the group with posterior circulation stroke, and a shorter “door-to-needle” time in strokes involving the anterior circulation. Characteristics of occlusions in the anterior and posterior circulation are summarized in Table 3. Positive dense artery signs were observed in 8 out of 19 anterior circulation patients (42.1%) and in 4 out of 7 (57.1%) posterior circulation patients. No statistically significant differences in thrombus density were detected by non-contrast CT and no differences in thrombus length were detected by CTA in the anterior and posterior vasculature. Good functional outcomes (mRs 0–2) were achieved in 78.9% of the subgroup of patients with anterior circulation stroke and in 75% of patients with posterior stroke. Overall, 73.7% of patients with AIS in the anterior circulation and 50% of patients in the posterior stroke group had an excellent clinical outcome (mRs 0–1) at 90-day follow-up.

All patients underwent an immediate thrombectomy approach. Thirteen patients (48.1%) received bridging IVT before the endovascular thrombectomy (EVT), 8 patients with anterior circulation stroke and 5 patients with posterior circulation stroke. None of the patients receiving IVT before the EVT reached successful recanalization of the target vessel after the administration of tissue plasminogen activator (tPA).

Three patients suffered from tandem artery occlusion in the anterior circulation, affecting the internal carotid artery (ICA) and the M2 segment of the MCA. In 2 patients, the anterograde approach was necessary with angioplasty of the proximal ICA and aspiration thrombectomy of the MCA afterwards, and 1 patient had periprocedural carotid artery stenting because tight stenosis with plaque ulcerations persisted after the percutaneous transluminal angioplasty (PTA). One patient had the retrograde approach, with periprocedural angioplasty of the proximal ICA and delayed internal carotid artery stenting 6 days after thrombectomy. All of the patients with TAO received dual antiplatelet therapy with acetylsalicylic acid (ASA) and clopidogrel per protocol. The patient with periprocedural stenting of the ICA during thrombectomy had immediate initiation of secondary stroke prevention with a loading dose of ASA (300 mg) and clopidogrel (300 mg), as no IVT was given in this case.

Discussion

LIMITATIONS OF THE STUDY:

Our study has significant limitations, most of them due to its retrospective observational nature, non-controlled design, and small cohort of patients. The limitations also include the potential for selection bias, as well as treatment procedures in different vascular territories without a matched cohort.

Conclusions

In conclusion, aspiration thrombectomy with ADAPT in LVO patients with low NIHSS scores may be safe and feasible. Our results support the use of mechanical thrombectomy in this group of patients, but randomized clinical trials are needed to establish the optimal management approach for this challenging patient population.