Manual thromboaspiration technique as a first approach for endovascular stroke treatment: A single-center experience

Abstract

Background

For intracranial large vessel occlusion in acute ischemic stroke (AIS), a high degree of revascularization in the minimal amount of time predicts good outcomes. Recently, different studies have shown that the direct aspiration first pass technique (ADAPT technique) for AIS obtains high recanalization rates, fast interventions and low costs when it works as first attempt. This study retrospectively describes revascularization efficacy, duration of procedure, intra and post-procedural complications, early and after 90-days clinical outcome in a group of patients who underwent ADAPT as the primary endovascular approach, eventually followed by stent retriever thrombectomy, for recanalization of large vessels in the anterior circulation.

Materials and methods

We analyzed clinical and procedural data of patients treated from April 2014 to August 2015. Recanalization was assessed according to the Thrombolysis in Cerebral Infarction score. Clinical outcome was evaluated at discharge and after 3 months (modified Rankin Scale, mRS).

Results

Overall, 71 patients (mean age of 69.7 years) were treated. Sites of occlusion were anterior circulation (including seven tandem extracranial-intracranial occlusions). In 39 patients i.v. rtPA was attempted. Recanalization of the target vessel was obtained in 87.3% of cases whereas direct aspiration alone was successful in 46/71cases (64.8%) with an average puncture-to-revascularization time of 43.1 minutes. Symptomatic intracranial hemorrhage occurred in 7.8% and embolization to new territories in 5.6%. In total, 38 patients (53.5%) had a good outcome at 90 days follow-up.

Conclusions

In our series, the manual thromboaspiration technique has been shown as fast and safe, with good rates of vessel revascularization in 87.3% of patients and neurological outcome <3 mRS in 53.5% of patients.

Introduction

For intracranial large vessel occlusion in acute ischemic stroke (AIS), a high degree of revascularization in the minimal amount of time predicts good outcomes.^1,2 To improve the low recanalization rate of tissue plasminogen activator (tPA), mechanical thrombectomy has been developed with two main methods: physical grasping and removal of thrombi with retrieval devices, and aspiration of occlusive thrombi with suction devices.³ Recently, different studies have shown that the direct aspiration first pass technique (ADAPT technique) for AIS obtains high recanalization rates, fast interventions and low costs when it works as a first attempt.^4-13

This study retrospectively describes revascularization efficacy, duration of procedure, intra and post-procedural complications, early and after 90-days clinical outcome in a group of patients who underwent ADAPT as the primary endovascular approach, eventually followed by stent retriever thrombectomy, for recanalization of large vessels in the anterior circulation.

Materials and methods

We performed a single-center retrospective data collection to find all patients who received ADAPT between April 2014 and August 2015 from our Neurointerventional Unit.

Patient selection, imaging and clinical assessment

Inclusion criteria were: (i) age ≥ 18 years; (ii) large artery occlusion in the anterior circulation; (iii) a time window less than 6 h; (iv) no intracerebral hemorrhage (ICH); (v) an Alberta Stroke Program Early CT score (ASPECTS) ≥ 6 at baseline computed tomography (CT); (vi) no or poor neurologic response to tPA administration, or contraindications to tPA.

All patients underwent unenhanced CT to exclude hemorrhage and assess ASPECTS score, and CT angiography to detect large vessel occlusions. In case of uncertain onset of the symptoms (i.e. wake-up stroke), patients were considered eligible for endovascular therapy (EVT) when salvageable brain parenchyma was depicted by perfusion CT mismatch. All patients were evaluated by a stroke-dedicated neurologist. All angiographic images were re-evaluated after the procedure and Thrombolysis in Cerebral Infarction (TICI) score was applied. Procedural timings were obtained from the angiographic records. Technical success was defined as recanalization of the target vessel according to TICI score ≥ 2 b. National Institutes of Health Stroke Scale (NIHSS) at admission and discharge, and modified Rankin Scale (mRS) after 90 days follow-up were assessed by the same stroke-dedicated neurologist. A good outcome was defined as a mRS score ≤ 2 at 90 days. Mortality was defined as death occurring within 90 days of initial presentation. Intra and post-procedural complications including symptomatic (worsening by ≥ 4 points NIHSS at clinical examination) and asymptomatic ICHs were recorded. Before treatment informed consent was obtained from the patient if conscious, or from a legal representative.

Technique

The thromboaspiration technique has been previously described by many authors.^4-10 Briefly, a large guide catheter was advanced into the internal carotid artery (ICA) as distally as possible, to reach the cervical or proximal petrous tract of ICA. Three types of aspiration catheters were used: 5MAX ACE (Penumbra, Alameda, California, USA), 4MAX (Penumbra Alameda, California, USA) and 3MAX (Penumbra Alameda, California, USA). The catheter was advanced in front of the thrombus, coaxially over a microwire (and eventually a microcatheter) and then manual aspiration was applied, with a 20 ml syringe for 3MAX and 4MAX catheters and with a 60 ml syringe for 5MAX ACE catheters; a second negative pressure was applied through a syringe of 60 ml, connected at a large guide catheter (Figure 1).

Figure 1.

(a)Thrombus in left middle cerebral artery; coaxial catheter in internal carotid artery (black arrow), just up bifurcation; microcatheter and microwire beyond the clot (green arrow). (b) Distal direct thromboaspiration (red arrow) and pulling out of the systems, during double continuous aspiration. (c) The coaxial system and the syringes to apply negative pressure for manual thromboaspiration are shown.

As soon as the absence of flow was noted within the aspiration system, the catheter was slowly advanced to ensure solid engagement with the thrombus. Aspiration was left for approximately 1 minute. When no flow through the system was found, the catheter was withdrawn. When aspiration alone did not result in successful revascularization, a stent retriever was added through the large bore catheter (Figure 2). The choice of aspiration catheter depended on the vessel involved: usually, 3MAX and 4MAX in M2 segment and 5MAX ACE in ICA terminus, middle cerebral artery M1 segment and tandem extracranial/intracranial occlusions. In tandem occlusions, thromboaspiration of intracranial and extracranial anterior circulation arteries might be associated with carotid stenting and/or percutaneous transluminal angioplasty (PTA).

Figure 2.

(a) Thrombus in left middle cerebral artery; coaxial catheter in internal carotid, just up biforcation (black arrow); microcatheter and microwire beyond the clot (red arrow). (b) A stent retriever is positioned into the thrombus (green arrow) and pulled out during distal and proximal thromboaspiration. (c) Coaxial system and the syringes to apply negative pressure for manual thromboaspiration are shown.

Results

Patient demographics and procedural data

Between April 2014 and August 2015, 71 patients (36 females and 35 males), with an average age of 68.7 years (range 32–86), were admitted to our institution for AIS. Sites of occlusion were: ICA terminus in 18 patients (eight right, 10 left), middle cerebral artery M1 segment in 30 (16 right, 14 left), M2 segment in 16 (five right, 11 left), tandem extracranial/intracranial occlusions in seven (three right, four left).

Before EVT, tPA administration was attempted in 39 patients. Average ASPECTS score at diagnosis was 8.7 (range 6–10). The average NIHSS at baseline was 19.1 (range 2–35). General anesthesia was performed in 69 patients. The remaining two patients had mild sedation.

The average time between onset symptoms and groin puncture was 242 min (range 152–458). Recanalization of the target vessel was obtained in 62 cases (87.3%). The primary ADAPT revascularization catheter was 5MAX ACE in 55 cases, 4MAX in 12 cases, and 3MAX in four cases.

The ADAPT alone was successful in achieving revascularization of the occluded vessel in 53 cases, including seven tandem occlusions with an average of 1.6 aspiration attempts. In 18 cases a stent retriever was added to complete recanalization.

In the tPA group 35/39 patients had a TICI > 2 b (3/35 after stent retriever) and 27/32 patients in the non-tPA group had a TICI > 2 b (6/32 after stent retriever).

The average puncture-to-revascularization (PTR) time was 41.5 minutes (range 12–72) in the ADAPT-alone group and 74.4 minutes (range 42–113) in the combined aspiration–stent retriever group.

There were no cases of embolization to a new territory (ENT). No significant vasospasm, dissection or endothelial lesion of intracranial vessels was caused by the aspiration catheters.

Clinical outcomes

The average NIHSS at discharge was 7.5 (range 0–35); 38 patients (53.5%) had a good outcome (mRS ≤ 2) at 90 days follow-up. In the 53 cases where ADAPT alone was used, 28 patients (5/7 tandem) achieved a mRS ≤ 2. In the 18 cases where ADAPT required a stent retriever, 10 patients achieved mRS ≤ 2. Hemorrhagic symptomatic events occurred in four cases (5.6%). There have been no cases of intra-periprocedural complications. Overall mortality was seven (10%) but four patients died from unrelated causes.

Discussion

The thromboaspiration technique, also called ADAPT, manual aspiration thrombectomy (MAT) or forced-sunction thrombectomy, combines modern aspiration and retrieval technology to achieve revascularization in AIS^4-13 with reliable, cost-effective results.⁶ The reperfusion catheters extract the clot with a negative pressure through a syringe connected to the proximal hub of the catheter. Technically, any stent retriever can be introduced easily through the reperfusion catheters, and the system proved to be versatile enough to treat even more resistant clots; with no procedure through the clot, ADAPT has low risk of perforation of the intracranial vessel.⁷

To date, the larger multicenter randomized controlled trials have used stent-retrievers as devices for thrombectomy, proving their better rates of recanalization, smaller residual territory of stroke on follow-up brain imaging, and better clinical outcomes compared with best medical therapy and other endovascular techniques.^14-16 In addition, a recent basic science study¹⁷ comparing stent retriever mechanical thrombectomy techniques with direct aspiration concluded that the latter significantly increases the risk of fragmentation of smaller soft elastic clots.

In our experience, ADAPT is considered the first-choice revascularization technique for large artery occlusion in the anterior circulation; this study confirms good recanalization results with 64.8% TICI rates when used alone and final 87.3% when stent-retrievers are introduced. Final revascularization rates are comparatively similar in our population and in two previous non-randomized retrospective studies (87.3% versus 86.6%⁷ and 95%⁴). In addition, the extraction of the occlusive embolus en bloc with a single aspiration attempt was achieved in 41% of cases and no cases of ENT occurred.

In our study three types of catheters (3MAX, 4 MAX and 5MAX ACE) were used. Their main characteristics are the easy navigability in intracranial arterial vessels and the distal large inner diameters. All these systems produce a different aspiration force on the clot; an in vitro study by Hu and Stiefel¹⁸ showed that the Penumbra 5MAX ACE catheter had the greatest aspiration rate with the greatest tip force. More recently, high-performance catheters designed to remove large clots have been introduced to market (i.e. Penumbra ACE 64 and Sofia PLUS) to optimize pushability and supple navigation.¹³

Tandem extracranial/intracranial anterior circulation occlusions independently predict poor outcome after intravenous thrombolysis.¹⁹ Unlike other ADAPT studies,^4,7 we treated a 10% rate of tandem occlusions. In our series, intracranial occlusions in tandem lesions were treated with ADAPT alone in 5/7 cases and ADAPT associated with stent retriever in 2/7 cases (Table 1); in four patients, cervical ICA artery stenting was performed, in one case in association with angioplasty; in two ADAPT alone was performed. In our series, we found a mRS ≥ 2 in 71%, better than outcome rates reported in previous studies.^20,21

Table 1.

Baseline characteristics of the patients, procedural timing, revascularization results and clinical outcome.

	All (71)	Aspiration only (46)	Aspiration + SR (18)	Tandem (7)	p-value
Age (mean (range))	68.7 (32–86)	69.2 (32–85)	70.6 (40–86)	61.2 (49–75)	0.145
Male sex (n (%))	35 (48.2)	20 (43.5)	7 (38.8)	4 (57.1)	0.950
ASPECT (mean)	8.7	8.6	8.56	8.43	0.779
Baseline NIHSS (mean (range))	19.1 (2–35)	18 (6–28)	21 (4–32)	21.43	0.156
tPA (n (%))	39 (54.9)	29 (63.4)	5 (27.7)	5 (71.4)	0.008
PTR (mean (range))	50.6 (15–160)	43.1 (15–145)	67.9 (35–160)	55.7 (20–105)	0.001
TICI ≥ 2 b (mean (%))	62 (87.3)	39 (84.8)	16 (88.9)	7 (100)	0.819
sICH (n (%))	4 (5.6)	3 (6.5)	0 (0.0)	1 (14.2)	0.234
90 days mRS ≤ 2 (mean (%)	38 (53.5)	23 (50)	10 (55.6)	5 (71.4)	0.842

PTR: Time from groin puncture to revascularization (min); sICH: symptomatic intracranial hemorrhage.

Our study confirms that ADAPT allows a short procedure. Turk et al.⁴ reported an average time from groin puncture to final revascularization of 37 minutes; Kowoll et al.⁷ reported 41 minutes; Romano et al.¹³ reported 57.8 minutes. The longer time for revascularization in the thromboaspiration plus stent retriever group is explained by the fact that thromboaspiration alone was first attempted and failed for a mean 1.6 attempts.

Regarding clinical outcome, we found the lower published mortality rate (1.4%) and a favorable outcome at 90 days follow-up in 53.5% of our cases, which is outstanding compared with the results of previous thromboaspiration technique studies.^4,7,9

Symptomatic hemorrhagic complication rate was 5.6%, in line with the cut-off value of 12% stipulated as standard of practice by the international multisociety guidelines of 2013⁵ and better than reported in most stent retriever studies.

The main limitation of our results is the retrospective design of the study. Until evidence of the efficacy of ADAPT becomes available, the standard of care is stent retriever as first pass based on previous randomized clinical trials.^14-16 Nonetheless, in our daily practice, ADAPT appears fast, effective, and safe among endovascular techniques for large vessel occlusions. In conclusion, a well-designed, prospective trial comprising large series of patients exploring ADAPT versus stent retriever is still needed to determine if this strategy is really worthwhile.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.