International Stroke Conference (ISC)
February 17-19, 2016
February 17, 2016
Since endovascular treatment has become standard of care, we are still grappling with the question of which patients have the most benefit, and really, are there patients that would not benefit. This was a standing room only session at ISC 2016 reviewing how much we know (and don’t know) about selecting patients for endovascular treatment, broken down into five major topics.
· Topic 1: Stroke severity – There is a paucity of data for outcomes in low severity strokes after both endovascular treatment and IV tPA. Many of these patients were excluded from the major IV tPA clinical trials. In terms of endovascular treatment, of 1200+ patients in the 5 endovascular trials, only 14 patients had low NIHSS of 0-5. Subgroup analyses of patients grouped by NIHSS as well as a meta-analysis of the 5 endovascular trials did not show a treatment effect of NIHSS on outcome. Ongoing trials to address this knowledge gap are forthcoming, including PRISMS, TEMPO2, and VISTA.
· Topic 2: Age – Similar to topic 1, evidence is limited. The endovascular trials did provide some subgroup analyses on dichotomized age groups, but most of the breakpoints were at ages significantly younger than 80. For example, for SYNTHESIS, analysis was dichotomized at the age group of 67. For IMS 3, it was dichotomized at 65 years. In neither trial did age have a treatment effect on outcome. MR CLEAN did have patients over age 80 and showed a benefit but with a wide confidence interval due to small numbers. Bottom line, age alone is not a sufficient reason to withhold treatment.
· Topic 3: Imaging – Are there specific imaging markers that should dictate moving forward with endovascular treatment? Pre-specified analysis of data from MR CLEAN for patients with ASPECTS 0-4, 5-7, and 8-10 showed no safety concerns but suggested benefit was likely greatest in the middle group, although the group in the lowest ASPECTS score was underpowered. Presence of mismatch on perfusion in MR CLEAN did not have a significant interaction on benefit; however, collateral imaging, based on a collateral grade on CTA did. The guideline for treatment is currently non-contrast CTH and CTA, to identify intracranial ICA or M1 occlusion and an ASPECTS of 6 or above, but forthcoming studies including DEFUSE 3 will help to refine this paradigm.
· Topic 4: Time – When is it too late? The reality is that although time is brain, treatment is focused on penumbra salvage, and penumbra growth is time dependent and individualized. Growth rate is likely determined by presence or absence of collaterals. Results of DEFUSE 2 suggests that if you have good collaterals, what matters is that you re-perfuse, not the time from ictus. DAWN and DEFUSE3 will look at imaging selection and thresholds for endovascular treatment in stroke patients in the extended window after 6 hours and wake-up strokes.
· Topic 5: Occlusion site – The mantra seems to be, just because we can reach the occlusion, doesn’t mean we should. Among things to consider are: (1) the pattern of occlusion – i.e. is there a tandem occlusion, is it an iatrogenic occlusion, (2) tissue viability – if the area is infarcted, there may not be a benefit, and in fact, may be harmful, to re-perfuse, (3) the eloquence of the area affected, and (4) individualized disability. Occlusion of the distal sites, especially M2, tend to be clinically heterogeneous, and an approach that takes into account all the aforementioned is recommended.
– Peggy Nguyen, MD