ADAPT Thrombectomy in ICA Terminus to MCA: Does the Location of Thrombus and Vessel Diameter

Matter?Joseph Brazzo III; Jeffrey Beecher; Antoni Szeglowski; Anthony Yan; Vernard Fennell; Hussain Shallwani; Hakeem Shakir;

Gursant Atwal; Elad Levy; Adnan Siddiqui

IntroductionMechanical thrombectomy (MT) withstentrievers as well as aspiration havebeen demonstrated to be efficacious instroke rescue. Currently, there are severaltrials comparing a direct aspiration firstpass technique (ADAPT) to stentrieveranalyzing first pass success rates.Anatomic variations from patient to patientmay play a significant role in success ofone technique over another. In this studywe define successful ADAPT as achievingrevascularization after a singlethrombectomy pass, and unsuccessfulADAPT requiring subsequent passes.Three anatomic variables were assessedand their relationship to a successfulADAPT was analyzed.1) Difference in vessel lumen diameter andinner diameter (ID) of aspiration catheter atthe clot interface2) Distance of clot from the internal carotidartery (ICA) bifurcation a) Absolute Distance b) Categorization of clot distance asbeing in the proximal half or distal half ofthe MCA defined as M1a and M1b,respectively3) The angle made by the ICA bifurcationbetween the distal ICA and M1 segment ofthe MCAUltimately, the purpose of this study was toidentify the optimal anatomic variables forADAPT success.

MethodsWe retrospectively reviewed our strokedatabase from January 2012 to June 2017for all M1 segment MCA thromboticocclusions that utilized ADAPT formechanical thrombectomy. Patients wereincluded if they were treated with ADAPTand had an isolated M1 occlusion.Exclusion Criteria:- Cases were excluded if they hadsimultaneous tandem occlusions orpseudoocclusions proximal to the MCA- ICA terminus, M2, or more distalocclusionsThe pre-retrieval angiogram was used tocalculate the vessel lumen diameter at thethrombus interface, and the distance fromthe ICA-T to the thrombus. The post-retrieval angiogram was used to calculatethe absolute distance of the M1 segment(from ICA bifurcation to MCA bifurcation),and to determine if the thrombus waslocated in the M1a segment (first half of theM1) or M1b (second half of the M1). Thevessel diameter was then compared to theID of the aspiration catheter used in clotretrieval.Measurements were collected separatelyby two authors for each patient who wereblinded to the success of ADAPT.Investigators took 2 calculations for eachcontinuous variable measurement, whichwere averaged for a single weightedmeasurement used for analysis (Image 1).We analyzed our results focusing onnumber of passes (1 pass vs. 2 or more)vs. difference of vessel lumen diameter andID of the catheter, distance of clot from ICA-T, and the angle of the distal ICA and M1segment. Furthermore, the recanalizationthrombolysis in cerebral infarcation (TICI)perfusion scale (2b and greater or less than2b) was utlized to evaluate ADAPTsuccess as well.Statistics:Student t-test was used for continuousdependent variables (one- and two-tailed)Fisher Exact test was used for categoricaldependent variables (one-tailed)

Results

A total of 32 cases were included inour study after meetingexclusion/inclusion criteria, with 19requiring ADAPT only (group 1), and13 requiring 2 or more passes afterADAPT (group 2). Furthermore, ourstudy included 20 females and 12males; 18 right-sided occlusions and14 left-sided occlusions.

At the 0.05 alpha level, none of ourvariables were statistically significant(Figures 1 & 2); however, it should benoted that there were strong trends amongADAPT success and smaller difference invessel diameter and catheter ID (p=0.126),and larger distance to clot from ICA-T(p=0.172); with the strongest trend being asmaller or more acute angle between theICA-T and MCA (p=0.105). Weaker trendscould be found between ADAPT successand clot being in M1b (p=0.2776), andlonger M1 length (p=0.243). There was notrend or difference in ADAPT success andrevascularization outcomes (TICI score)(p=0.6552).

Image 1.

Figure 1.

Figure 2.

Conclusion

Our data demonstrates a trend towardsincreased success with ADAPT as thedifference between the vessel diameterand ID of the aspiration catheterdecreases. Interestingly, vessel diameteralone had no significant association withADAPT success. Furthermore, there is asimilarly strong trend of a longer distanceto occlusion in the M1 segment withADAPT success; and weaker trend of alonger M1 segment of the MCA in thosewith the success of ADAPT. Similarly, astrong trend exists between first passrecanalization with ADAPT and M1bthrombi, a surrogate for clot distance andvessel diameter. To our surprise we alsofound ADAPT success to have thestrongest trend with a more acute orsmaller angle of the ICA-T and MCA, forreasons unknown. Taken collectively,although our results prove to be statisticallyinsignificant at the 0.05 alpha level,limitations must be considered. Theseinclude a small statistical power as definedby our small number of cases included inthe study; as well as investigators notexperts in radiographic measurements. Webelieve with a larger sample size andexpert measurements, it can be shown thatthe use of ADAPT is ideal for clots in thedistal M1 segment of the MCA assuminguse of an appropriate aspiration catheterID.

Learning ObjectivesADAPT is a well-studied, proventechnique for mechanicalthrombectomy

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Patient specific anatomic variationsmay effect the success of mechanicalthrombectomy

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ADAPT success increases as thevessel diameter decreases for M1occlusions

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Vargas J, Spiotta A, Fargen K, et al. Longterm experience using the ADAPT techniquefor the treatment of acute ischemic stroke. JNeurointerv Surg doi:10.1136/neurintsurg-2015-012211

Turk AS, Frei D, Fiorella D, et al. ADAPTFAST study: a direct aspiration first passtechnique for acute stroke thrombectomy. JNeurointerv Surg 2014;6:260–4.