BACKGROUND
The IMS III Trial did not demonstrate clinical benefit of the endovascular approach compared to IV rt-PA alone for moderate or severe ischemic strokes (NIHSS≥8) enrolled within three hours of stroke onset. Late reperfusion of tissue that is no longer salvageable may be one explanation, as suggested by prior exploratory studies showing an association between time to reperfusion and good clinical outcome. We sought to validate this relationship in the large-scale IMS III trial, and consider its implications for future endovascular trials.
METHODS
The analysis consisted of the endovascular cohort with proximal arterial occlusions in the anterior circulation that achieved angiographic reperfusion (TICI 2–3) during the endovascular procedure (within 7 hours from the onset of symptoms). Logistic regression was used to model good clinical outcome (90-day modified Rankin 0–2) as a function of the time to reperfusion, and prespecified variables were considered for adjustment.
FINDINGS
Among 240 proximal vessel occlusions, angiographic reperfusion (TICI 2–3) was achieved in 182 (76%). Mean time to reperfusion was 325 minutes (range 180–418 minutes). Longer time for reperfusion was associated with a decreased likelihood of good clinical outcome (RR [95% CI] for every 30 minute delay: unadjusted 0·85 [0·77–0·94]; adjusted 0·88 [0·80–0·98]).
INTERPRETATION
We confirm that delay in time to angiographic reperfusion leads to a decreased likelihood of good clinical outcome. Achieving rapid reperfusion may be critical for the successes of future acute endovascular trials.
FUNDING: NIH/NINDS (study sponsor), Genentech Inc. (study drug - intra-arterial t-PA), EKOS Corp. (device), Concentric Inc. (device), Cordis Neurovascular, Inc. (device), and Boehringer Ingelheim (European Investigator Meeting support).