Background: Endovascular therapy (EVT) is the standard of care for acute ischemic stroke (AIS) due to large vessel occlusion (LVO) with NIHSS ≥ 6. LVO patients may present with mild (NIHSS <6) but disabling deficits and were not well represented in RCTs resulting in a NIHSS cutoff of ≥ 6 on AHA guidelines. Milder deficits may not justify EVT risk-benefit ratio. To generate practice level data, we evaluated EVT treatment effect in mild stroke.
Methods: A retrospective cohort from 8 USA and Spain centers of AIS with LVO in the anterior circulation with NIHSS ≤ 6 presenting within 24 hrs (1/12 to 3/17) was pooled. EVT patients were compared with those only treated with medical management (MM). 90 day mRS (0-1 excellent) was chosen as the primary outcome as an appropriate goal for mild stroke. Multivariable analyses compared the treatment effects and their interactions with NIHSS, both as an ordinal and dichotomized (0-3 vs 4-5) variable. Adjustment was made for age, time LSN to EVT center arrival, IV-tPA, occlusion site and ASPECTS. Within center correlation was accounted for.
Results: 223 patients were included (EVT 105, MM 118). The two groups had similar baseline age (65.7 and 66.3 yrs, p=0.73), ASPECTS (9.4 and 9.3 p=0.53), %IV t-PA (39% and 36% p=0.65) and median (IQR) time mins to EVT center 156(66.5-301) and 212(90-387) p=0.09, EVT and MM respectively. There was no difference in outcomes (54.6% EVT vs 53.4% MM) when all patients (NIHSS 0-6) were assessed (aOR 0.94, 95% CI 0.62-1.40, p=0.94); same for NIHSS 0-5 (55.1% EVT vs 55.6% MM), (aOR 0.95, 95% CI 0.71-1.26, p=0.95). For NIHSS 0-3, MM had better outcomes (51.9% EVT vs 74.6% MM), (aOR 0.39, 95% CI 0.25-0.61, p<0.01). For NIHSS 4-5, results favored EVT (57.1% EVT vs 22.2% MM), (aOR 4.04, 95% CI 2.56-6.38, p<0.01). Fig 1, 2 show CIs of EVT and MM as related to NIHSS.
Conclusion: Though limited by a non-randomized comparison, the data suggest a possible benefit for EVT in mild strokes with NIHSS 4-5. In NIHSS ≤3, the intervention had no additive benefit.