Article Text
Abstract
Introduction While successful reperfusion is the goal of mechanical thrombectomy (MT), the main mode by which MT devices facilitate this outcome - the ability to physically retrieve clot - is typically not collected directly in clinical series; and even studies reporting clot composition have a common limitation in that they only include patients where clot material was removed and analyzed and leave out the population with no clot retrieved. In contrast, the EXCELLENT neurothrombectomy registry (NCT03685578) captured whether or not any clot material was removed with each MT pass, in addition to angiographic and clinical outcomes. The dataset offers the opportunity to evaluate real-world cases where MT yielded only ‘empty’ passes and to identify potential pre-procedure indicators of clot that is challenging to retrieve using current technology.
Patients and Methods From 09/2018 to 03/2021, 997 ‘all-comer’ patients (mean age: 70.0±14.2, 51.8% female, 19.7% self-reported non-Caucasian) treated with EMBOTRAP in the first MT pass were enrolled at 34 international sites. ‘Was clot retrieved?’ was captured with every MT pass for every participant. The study utilized a core imaging lab blinded to clinical data, an independent 90-day mRS assessment and a Clinical Events Committee.
Results MT yielded no clot in any pass in 120 cases vs 877 with clot removed in at least 1 MT pass. Notable pre-procedure findings include lower% hyperdense vessel sign (HDVS) on CT/susceptibility artery sign (SAS) or MRI at baseline, per core lab (58.9% vs 74.7%; p<0.001), a trend towards lower baseline NIHSS scores (14.8±7.1 vs 15.7±6.8; p=.065) and longer times from stroke onset to puncture (547.8±569.9 vs 457.8±445.4 minutes; p=.053) in the no clot group. Outcomes for the 2 groups are summarized in the table 1, with reperfusion of 2b-3 of 60.8 vs 63.6% with first pass (p=.558), final 2b-3 of 85.8 vs 95.7% (p<.001) in the no clot vs clot groups. NIHSS improvement at 24 hrs was lower (p<.001) and 90-day mortality was higher (p=.035) in the no clot group.
Conclusion This is the first report of cases where MT maneuvers failed to remove any clot material. Although reperfusion may be achieved without clot removal (e.g. compression, fragmentation, autolysis, accidental loss), this population represents a target for improvement in MT technology and can inform future device design. The results provide insight into the characteristics of this population with suboptimal outcomes and support the notion that no retrieval may be correlated with imaging findings suggesting clot lower in RBC. Both trends in lower NIHSS and longer times to treatment, as well as lack of HDVS/SAS on imaging are known to be associated with intracranial atherosclerotic disease, perhaps pointing to underlying vessel disease as target for technological improvement in some of the cases with no clot retrieved.
Disclosures A. 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