Abstract 176: Perfusion Instability Impacts Tissue Outcome Beyond 6 Hours After Ischemic Stroke Onset
Background: During the first 24 hours after stroke, brain perfusion is highly dynamic. While early reperfusion can salvage tissue, it is unclear if late perfusion changes affect tissue fate. We examined perfusion changes between 6 and 24h after stroke onset and its impact on tissue outcome using a voxel-based approach.
Methods: Mean transit time (MTT) and FLAIR maps were obtained in 27 ischemic stroke patients (median NIHSS: 14) at 3, 6, and 24h after onset to measure perfusion change; and at 1mo to assess tissue fate (dead or alive). MTT prolongation (pMTT) was calculated as: MTT - (median MTT of the non-ischemic hemisphere). At 2 time intervals (3-6h and 6-24h), perfusion change was classified into 3 categories: stable (|pMTT t1-t2| ≤ 2s), improved (|pMTT t1-t2| < -2s), or worsened (|pMTT t1-t2|>2s), pooling voxels from all patients. Infarct probability was plotted as a function of pMTT at 3h and 6h for stable, improved, or worsened perfusion.
Results: Across the range of pMTT (0-22s), perfusion change was observed in a median of 76% (57% improved; 19% worsened) of tissue for 3-6h and 83% (66% improved; 17% worsened) of tissue for 6-24h. To determine the impact of dynamic perfusion on tissue fate, 3 infarct probability curves were plotted for improved (green), stable (blue), and worsened (red) perfusion between 3-6h (Fig A) and 6-24h (Fig B). As expected, early (3-6h) perfusion improvement or worsening impacted tissue fate for pMTT values 2-18s (yellow and purple region), likely representing penumbral tissue. Surprisingly, late perfusion change (6-24h) also influenced infarct probability, though its influence was restricted to milder pMTT of 2-14s (yellow region), suggestive of a closing therapeutic window.
Conclusions: Late perfusion changes impacted tissue fate for pMTT 2-14s suggesting that regions of milder ischemia may have a longer therapeutic window than regions of more severe ischemia. Such tissue could be targeted for intervention beyond current treatment windows.
Author Disclosures: H. An: None. A.L. Ford: None. C. Eldeniz: None. Y. Chen: None. K.D. Vo: None. W.J. Powers: None. J. Lee: None. W. Lin: None.
- © 2015 by American Heart Association, Inc.