Abstract W P62: Rapidly Improving Stroke Symptoms (RISS): A Prospective, Pilot Study

Background: “Rapidly Improving Stroke Symptoms” (RISS) is a controversial exclusion criterion for tPA treatment for acute ischemic stroke (AIS). Prior studies suggest 20-30% of those excluded from tPA solely because of RISS have poor outcomes. Objectives: (1) To estimate frequency and magnitude of RISS using prespecified RISS definitions; (2) To explore how different RISS definitions predict clinical outcome. Methods: A prospective, observational, pilot study of AIS patients presenting within 4.5 hours of symptoms. After informed consent, subjects were administered serial NIH Stroke Scales (NIHSS) by certified examiners every 20 (±5) minutes until a treatment decision (tPA vs no-tPA) was made by the treating physician, independently from the study. RISS was calculated as baseline NIHSS (bNIHSS) - treatment decision NIHSS (tdNIHSS). Definitions of RISS (based on prior literature and expert consensus) were: (1) change in NIHSS score ≥ 4 point improvement (IMP) or (2) % change in NIHSS score (a) ≥ 25% or (b) ≥ 50% IMP. Good outcome was defined as modified Rankin Scale (mRS)=0-1 at 3-month post stroke. Logistic regression was used to determine if definition(s) of RISS predicted good outcome. Results: Fifty AIS: mean age 65 yrs (±15 SD); male 56%; black 78%; prior stroke/TIA 28%; median bNIHSS score 8(IQR 2,11); before treatment decision was made, 2 serial NIHSS scores were obtained for the entire cohort, 3 scores in 26/50 (52%); median tdNIHSS score 5 (IQR 2,9); treated with tPA 23/50(46%). Frequency of RISS varied based on definition used: 10% for ≥ 4 point IMP, 22% for ≥ 25% IMP, and 12% for ≥ 50% IMP. In the overall cohort, 42% of patients had good outcomes: 17/27 (63%) not treated with tPA (bNIHSS 3; IQR 2,5) vs 6/23 (26%) treated with tPA (bNIHSS 9;IQR 5,15), p=0.02. There was a difference in tdNIHSS between those not given tPA (2;IQR 1,4) and those given tPA (8;IQR 6,13), p Conclusions: Our prospective, pilot data suggest that a serial NIHSS assessment prior to treatment decision is feasible and may help determine the frequency and magnitude of RISS for larger studies. In our cohort, AIS patients improved approximately 3 points on the NIHSS from baseline to tPA treatment decision.