Time to Reperfusion and Outcome in Acute Stroke
What is the specific relationship of different workflow metrics with clinical outcomes in a randomized trial of mechanical thrombectomy for acute stroke?
The investigators studied the mechanical thrombectomy group (n = 103) of the prospective, randomized REVASCAT (Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset) trial. They defined three workflow metrics: time from symptom onset to reperfusion (OTR), time from symptom onset to computed tomography (CT), and time from CT to reperfusion. Clinical characteristics, core laboratory-evaluated Alberta Stroke Program Early CT Scores (ASPECTS), and 90-day outcome data were analyzed. The effect of time on favorable outcome (modified Rankin scale, 0-2) was described via adjusted odds ratios (ORs) for every 30-minute delay.
Median admission National Institutes of Health Stroke Scale was 17.0 (14.0–20.0), reperfusion rate was 66%, and rate of favorable outcome was 43.7%. Mean (standard deviation) workflow times were as follows: OTR: 342 (107) minutes, onset to CT: 204 (93) minutes, and CT to reperfusion: 138 (56) minutes. Longer OTR time was associated with a reduced likelihood of good outcome (OR for 30-minute delay, 0.74; 95% confidence interval [CI], 0.59-0.93). The onset to CT time did not show a significant association with clinical outcome (OR, 0.87; 95% CI, 0.67-1.12), whereas the CT to reperfusion interval showed a negative association with favorable outcome (OR, 0.72; 95% CI, 0.54-0.95). A similar subgroup analysis according to admission ASPECTS showed this relationship for OTR time in ASPECTS <8 patients (OR, 0.56; 95% CI, 0.35-0.9), but not in ASPECTS ≥8 (OR, 0.99; 95% CI, 0.68-1.44).
The authors concluded that time to reperfusion is inversely associated with favorable outcome, with CT to reperfusion being the main determinant of this association.
This study reports a progressive decline of the probabilities of regaining a good functional outcome as time to reperfusion increases, overall a 26% decrease for every 30-minute delay. Furthermore, the time elapsed from symptom initiation to the admission CT scan was not associated with a decrease in the odds of good outcome in the treated patients; but time from CT to reperfusion showed a clear inverse relationship with the odds of good recovery. It appears that reducing the symptom to imaging time might increase the number of eligible patients for effective thrombectomy, but reducing the time from CT to reperfusion would increase the positive impact of thrombectomy in those patients selected for therapy. These data emphasize the need to develop strategies to minimize revascularization times for improved outcomes.
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