Abstract 124: Collaterals Determine Risk of Early Territorial Stroke and Hemorrhage in the SAMMPRIS Trial
Background: The degree of collateral circulation is a powerful risk factor for recurrent stroke in the setting of medical therapy for symptomatic intracranial atherosclerosis. The impact of collaterals on the short-term risk for stroke in patients treated by stenting or intensive medical therapies is not known. We systematically evaluated baseline angiographic features of collateral circulation and antegrade flow across intracranial stenoses in randomized subjects of the multicenter SAMMPRIS trial and correlated these to their 30-day risk of ischemic stroke.
Methods: Digital review of baseline angiograms in SAMMPRIS was conducted to score ASITN/SIR collateral grade and TICI antegrade flow, blind to other data. Dichotomized collateral and TICI scores (none/partial versus complete) were analyzed independently and in combinations with trial endpoints of territorial ischemic stroke or stroke in territory (SIT) and intracranial hemorrhage (ICH) within 30 days in the intensive medical and stenting arms of the study. Log-rank tests with follow-up time censored at 30 days were used in the analysis.
Results: Collaterals could be assessed on 376/424 baseline angiography studies available for digital imaging review for the 451 randomized subjects in SAMMPRIS (186 medical, 190 stenting). Early territorial stroke (SIT) occurred in 6/186 (3.2%) subjects in the medical arm and 20/190 (10.5%) after stenting. SIT was not associated with TICI in either arm, whereas collaterals exerted a potent protective influence in medical (p=0.067) and stented (p=0.004) cases, with 0/66 (0%) SIT in the medical arm and 0/51 (0%) SIT in the stented arm when collaterals were complete. SIT in medical cases was associated with partial TICI/partial collaterals (5/25 (20.0%)) versus complete TICI/partial collaterals (1/95 (1.1%)) and partial TICI/complete collaterals (0/66 (0%)), p<0.001. SIT in stented cases was associated with partial TICI/partial collaterals (11/46 (23.9%)) versus complete TICI/partial collaterals (9/93 (9.7%)) and partial TICI/complete collaterals (0/51 (0%)), p<0.001. ICH within 30 days occurred in 0/186 (0%) subjects randomized to medical therapy. In the stenting arm, early ICH occurred in 8/190 (4.2%) and was associated with TICI (p=0.036) and collaterals (p=0.077). Overall, early ICH after stenting was associated with partial TICI/partial collaterals (7/46 (15.2%)) versus complete TICI/partial collaterals (1/93 (1.1%)) and partial TICI/complete collaterals (0/51 (0%)), p<0.001.
Conclusions: Patients with impaired collateral flow associated with severe intracranial stenosis had the highest risk for stroke within 30 days, both with intensive medical therapy and as a complication of angioplasty and stenting.
- © 2012 by American Heart Association, Inc.