Article Text

Application of optical coherence tomography in decision-making of post-thrombectomy adjunctive treatments
  1. Di Li1,
  2. Tao Tang2,
  3. Teng Hu1,
  4. Piotr Walczak3,
  5. Dheeraj Gandhi3,
  6. Shen Li2
  1. 1 Department of Neurointervention, Dalian Municipal Central Hospital, Dalian, Liaoning, China
  2. 2 Department of Neurology and Psychiatry, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
  3. 3 Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
  1. Correspondence to Dr Shen Li, Department of Neurology and Psychiatry, Beijing Shijitan Hospital, Capital Medical University, Beijing, China; lishen{at}mail.ccmu.edu.cn; Dr Di Li, Department of Neurointervention, Dalian Municipal Central Hospital, Dalian, Liaoning, China; jzlidi{at}126.com

Abstract

An adult patient with acute basilar artery occlusion underwent mechanical thrombectomy. After complete reperfusion, a 70% residual stenosis of the proximal basilar artery was observed. Intravascular optical coherence tomography (OCT) identified lipid plaques with an intact fibrous cap and thrombus in the culprit lesion, indicating plaque erosion was the mechanism of in situ thrombosis. Adjunctive antiplatelet therapy rather than rescue interventions was pursued for its beneficial effects in acute coronary syndrome caused by plaque erosion. The patient had a 90-day modified Rankin Scale score of 0. OCT enables precise evaluation of vessel characteristics following thrombectomy, so may improve outcomes through subsequent tailored treatments.

  • Stroke
  • Thrombectomy
  • Stenosis
  • Plaque
  • Intervention

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Background

Severe parent vessel stenosis after mechanical thrombectomy (MT) is generally caused by intracranial atherosclerosis. This scenario is associated with instant or early re-occlusion and a worse outcome.1 Balloon angioplasty and/or stenting are important rescue treatments that can sustain vessel patency. However, there is a lack of consensus on optimal patient selection and the evidence for adjunctive rescue interventions remains low.2 Optical coherence tomography (OCT) provides useful insights regarding the characteristics of intrinsic vessel wall disease with high spatial resolution, so might be instructive for conjunctive treatment decision for MT patients. There is one earlier report of the use of OCT after MT to evaluate endothelial injury in three patients with posterior circulation occlusion who had no residual stenosis.3 We obtained IRB approval for OCT during MT and, to the best of our knowledge, applied OCT for the first time in a patient with acute basilar artery occlusion who had an underlying parent vessel stenosis after MT. Our patient benefited from OCT in determining the etiology of the culprit lesion and subsequent tailored treatment.

Case presentation

An adult patient with a history of heavy smoking and drinking was admitted to the hospital with pre-existing 20-hour dizziness that gradually progressed to quadriplegia and somnolence 3 hours prior to admission. The baseline National Institutes of Health Stroke Scale (NIHSS) score was 27 for drowsiness, partial left-side gaze, quadriplegia, and mutism.

Investigations

Non-contrast head CT did not reveal intracerebral hemorrhages or established infarctions. The posterior circulation Alberta Stroke Program Early CT Score was 10. CT perfusion showed extensive hypoperfusion in the posterior circulation without significant core infarction. CT angiography derived from CT perfusion datasets revealed acute basilar artery occlusion (RAPID software; iSchemaView, Menlo Park, California, USA).

Treatment

The patient underwent digital subtraction angiography (DSA) and the basilar artery occlusion was confirmed (figure 1A). Successful MT was performed using a Solitaire stent retriever (Medtronic) assisted by a Catalyst-6 (Stryker) intermediate catheter under general anesthesia. While a modified Thrombolysis in Cerebral Infarction (mTICI) score of 3 was obtained after the first pass, an underlying 70% stenosis of the basilar artery was observed (figure 1B). The lesion was in a perforator-rich segment of the basilar artery encompassing the anterior inferior cerebellar artery. We then elected to use OCT for further evaluation and decision-making regarding adjunctive rescue interventions versus conservative management.

Figure 1

(A) Pre-thrombectomy and (B) post-thrombectomy digital subtraction angiograms.

A 2.7 Fr OCT catheter (Dragonfly Duo; St Jude Medical) was delivered along a microwire, passing through the stenosis to the distal segment of the basilar artery assisted by the Catalyst-6 catheter, with constant blood removal by injection of 8 mL undiluted iodixanol 320 (GE Healthcare Ireland, County Cork, Ireland) at a flow rate of 4 mL/s through the intermediate catheter for 2 s. OCT was performed at multiple levels of the basilar artery with a 36 mm/s automatic pullback speed. Image analysis was performed using an OCT system (IlumienOptis Imaging System, St Jude Medical).

Cross-sectional OCT images confirmed 70% stenosis in the culprit lesion and identified lipid plaques with an intact fibrous cap as well as intraluminal red and mixed thrombus (figure 2). The OCT pattern with intact fibrous cap was consistent with plaque erosion as described previously,4 rather than frank plaque rupture. In patients with acute coronary syndrome caused by plaque erosion (confirmed by OCT), antiplatelet therapy may reduce thrombus volume and promote good clinical outcomes.5 Thus, we did not pursue rescue interventions and started adjunctive continuous IV infusion of glycoprotein IIb/IIIa inhibitors (tirofiban, 0.1 μg/kg/min) for 24 hours after MT. There were no complications during the procedure. Both aspirin (100 mg) and clopidogrel (75 mg) were administered as bridging therapy 4 hours prior to the end of tirofiban infusion. The post-intervention NIHSS score was 4.

Figure 2

Optical coherence tomography evaluation of residual stenosis of the proximal basilar artery after mechanical thrombectomy. (A) Eccentric lipid plaque with intact fibrous cap (yellow arrowhead). (B) Lipid plaque with intraluminal red thrombus (red arrowhead) and mixed thrombus (blue arrowhead). (C) Concentric lipid plaque with intact thick fibrous cap (yellow arrowhead). (D) Lipid plaque (yellow arrowhead) with red thrombus (red arrowhead).

Outcome and follow-up

Follow-up MRI at 8 days did not reveal significant infarction. Only moderate basilar artery stenosis was observed (figure 3A). Plaque enhancement in the proximal basilar artery without intraluminal thrombus was detected on high-resolution MRI of the vessel wall (figure 3B). The patient had a 90-day modified Rankin Scale score of 0.

Figure 3

Follow-up magnetic resonance imaging. (A) Moderate stenosis of basilar artery on follow-up 3D time-of-flight magnetic resonance angiography. (B) 3D-contrast enhanced cube T1 weighted high resolution magnetic resonance vessel wall imaging showing vessel wall enhancement (white arrowhead) without intraluminal thrombus on the proximal basilar artery.

Discussion

Large artery atherosclerosis is the leading cause of acute basilar artery occlusion with poor outcomes after MT.6 One possible explanation is the high prevalence of underlying stenosis and refractory occlusions after MT, linked to unstable plaques resulting in a cascade of platelet activation and thrombosis.2 Outcomes can be improved by rescue interventions, with selection criteria mainly based on the degree of stenosis.7 However, the two-dimensional lumenogram derived by DSA cannot evaluate vessel wall pathology and plaque characteristics.

OCT enables evaluation of plaque composition, the burden of residual stenosis, and identifies increased plaque vulnerability, shedding light on mechanisms of in situ thrombosis and suggesting tailored rescue interventions.8 We used OCT to resolve the dilemma of whether rescue interventions with stenting may be necessary for a patient with severe residual stenosis in the perforator-rich segment of the basilar artery. While posterior circulation MT is still not supported by strong evidence,6 OCT might help as an adjunctive tool in further characterization of vessel pathology, thereby improving outcomes by application of optimum treatments.

Although OCT was successfully performed in this case after basilar artery thrombectomy, we should bear in mind that this technique is not yet approved for neurovascular applications.9 Our attempt with the Dragonfly system is an off-label venture investigating its role at our institution. In addition, the intermediate catheter Catalyst-6 is not intended for use with power injectors and caution is recommended. Development and translation of OCT systems for neurovascular use will add to the neurointerventionalist’s armamentarium. Encouragingly, great progress is being made in designing a new generation of OCT technology for neurovascular applications.10

Learning points

  • Optical coherence tomography was successfully performed in a patient after basilar artery thrombectomy with residual stenosis.

  • Optical coherence tomography can help to evaluate the etiology of residual stenosis and the mechanisms of in situ thrombosis after thrombectomy.

  • Providing crucial information on vessel characteristics, optical coherence tomography may aid tailored conjunctive treatment and favorable outcomes of thrombectomy patients.

Supplemental material

Ethics statements

Patient consent for publication

Ethics approval

The study was approved by the Ethical Committee of Dalian Municipal Central Hospital affiliated with Dalian Medical University (approval number 2022-035-01). Participants gave informed consent to participate in the study before taking part.

References

Supplementary materials

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Footnotes

  • DL, TT and TH contributed equally.

  • Contributors DL, TT, TH, PW, DG, and SL substantially contributed to the conception and manuscript drafting of the work. DL and TH performed the operative procedure and data acquisition. TT, PW, DG, and SL assisted in data analysis and revising the work. DL, TT, TH, PW, DG, and SL provided final approval for the version to be published. DL, TT, TH, PW, DG, and SL acknowledge and maintain the integrity of the work investigated.

  • Funding This study was funded by National Natural Science Foundation of China (82171319), Central Committee Healthcare Project (2020YB64), and the Emergency Project of Beijing Shijitan Hospital (2019-JJ02).

  • Competing interests SL received research funding support from National Natural Science Foundation of China. SL and TT received research funding support from Central Committee Healthcare Project and Emergency Project of Beijing Shijitan Hospital. PW is secretary of the Society for Image-Guided Neurointerventions (SIGN), and holds equity in Ti-com, LLC and Intra-Art, LLC. DG received research grants from Focused Ultrasound Foundation, INSIGHTEC and MicroVention.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.