International Stroke Conference
February 6–8, 2019
Burton J. Tabaac, MD
First Presenter: Xin Cheng, MD, PhD
This insightful discussion focused on the identification of intracranial atherosclerotic disease (ICAD) and its relationship to large vessel occlusion (LVO). The speaker pointedly detailed the differences in truncal type vs. branching type anatomies. This difference in dynamic may be correlated with baseline NIHSS and size of penumbra, with larger penumbra suggesting better collateral circulation. This portion of the talk was aided by neuroimaging to demonstrate the presence of a “susceptibility vessel sign” (SVS) on GRE/SWI MRI sequencing. If present, SVS suggests an embolic etiology, whereas the absence of SVS suggests ICAD.
The current treatment of ICAD-LVO lacks consensus amongst the scientific community. Notably, patients with ICAD were observed to experience much longer procedure times compared to patients with LVO of embolic origin. The presenter posed the question, “Is endovascular treatment, or even thrombosis, necessary in this subset of patients?” ICAD-LVO is highly common in Asian populations, and there are no definitive clinical and/or imaging profiles for ICAD-LVO patients. It remains to be clear how treatment and patient selection criteria will change, the take-away being that intervention is safe, but it is unclear if it is beneficial.
Second Presenter: Mark Parsons, MD, PhD, FRACP
For this segment of the talk, the discussion focused on the relationship between pre-treatment ischemic core and prediction of 3 month MRS (modified Rankin score). Multiple slides demonstrating brain neuroimaging were invoked as a useful visual aid to suggest that CTP (CT perfusion) conducted between 0 and 6hr from last known normal is strongly prognostic, whereas NCCT (noncontrast CT) ASPECTS score is not. The presenter was keen to note how ischemic core thresholds change with time to reperfusion.
Third Presenter: Pooja Khatri, MD
An outstanding portion of the “debate” and highly important perspective, as it relates to patient selection, is how to best treat patients with mild stroke. The presenter asked, “Who is excluded from mechanical thrombectomy when the NIHSS is less than 6?” The audience learned, 20-40% within this subset of presentation will decline and have neurological deterioration. More than half of significant clinical worsening occurs within the initial four hours of presentation. There is strong evidence for pursuing thrombectomy for patients who present with an NIHSS of 0-5.
The studies to date have demonstrated that clinical deterioration is not uncommon and the risk of mechanical thrombectomy is low. Currently, treatment for this portion of the stroke population has AHA Class 2b evidence. Given the small sample sizes for the aforementioned conclusions, more data is needed, ideally a randomized controlled trial.
Fourth Presenter: Bernard Yan, DMedSci, FRACP, MBBS
The final presenter of the afternoon session raised controversy as he challenged the conference to think about “direct” thrombectomy. In other words, is it ever appropriate to remove adjunct IV thrombolysis? Radically, the speaker asked, “Are there acute stroke patients with LVO, who present in less than 4.5 hours, that should be selected for intraarterial intervention, in which IV thrombolysis should be skipped!?” A current trial, DIRECT-SAFE, aims to compare bridging thrombolysis vs. direct mechanical thrombectomy. Current evidence suggests that bleeding complications and clinical outcomes after 3 months are similar between the two groups. Are there situations in which IV thrombolysis can add harm, e.g., incidence of sICH (secondary intracerebral hemorrhage)?
Clot migration (e.g., clot propagation from M1 to distal M2/M3) was shown to be associated with IV thrombolysis in the setting of acute ischemic stroke, thus making the retrieval of clot more difficult or completely inaccessible. In one study cited in the presentation, clot migration was documented 18% of the time status post IV thrombolysis vs. 3.8% for direct thrombectomy.
Overall thoughts and opinion:
Albeit this was not a classic “debate” in the conventional sense, the presentation was easily able to invoke interest and fervor amongst the full, standing room–only audience of attendees. Rather than “debating” each other, the four presenters were skillfully able to raise internal debates amongst ourselves. Each portion of the session was devoted to a unique angle and way to think about patient selection for mechanical thrombectomy. Clinical criteria was examined, neuroimaging was displayed, and the presenters awoke great excitement for future scientific study in an effort to answer these very questions.