Poor collateral status independently predicts developing malignant anterior circulation infarction
Flores A, Rubiera M, Ribó M, Pagola J, Rodriguez-Luna D, Muchada M, et al. Poor Collateral Circulation Assessed by Multiphase Computed Tomographic Angiography Predicts Malignant Middle Cerebral Artery Evolution After Reperfusion Therapies. Stroke. 2015
A potential fatal complication of ischemic stroke is malignant middle cereberal artery infarction (mMCAi) often requiring decompressive craniectomy. Therefore, early detection is paramount and several predictors have been evaluated. One such factor is leptomeningeal or pial collateral circulation (CC) status which has been associated with outcomes and infarct volume. Traditional single-phase CT angiogram (CTA) may lack temporal resolution to accurately detect collateral status but multi-phase CTA may improve CC evaluation. The relationship between CC and development of mMCAi is unknown and the authors predict that poor CC status may be an early predictor of malignant edema.
The study was a prospective study that enrolled consecutive ischemic stroke patients who presented less than 4.5 hours from onset with proximal anterior circulation occlusion. Collaterals were measured with a multi-phase CTA and scored on a 5 point scale with scores 0-3 given “poor” designation while 4 and 5 were stratified as “good”. The primary outcome was presence of mMCAi. In total, 81 patients were enrolled. 15 developed mMCAi with 5 requiring surgery. mMCAi patients presented more often with ICA occlusion and expectedly, had significantly higher infarct volume. 38 patients were identified as poor CC and there was significant association with mMCAi evolution. In the multivariate analysis, poor CC status was the only independent predictor of mMCAi.
This study shows that poor collateral status is an independent predictor of developing malignant infarction, especially in patients who did not achieve recanalization. Multi-phase CTA can identify patients who may be at higher risk of developing malignant edema, potentially requiring decompressive surgery. Early surgery can potentially improve prognosis and outcome. A potential limitation to this study was the low number of patients, especially in the mMCAi group (n=15). Furthermore, obtaining multi-phase CTA and timely radiological interpretation may not be readily available which could limit its utilization. Any delay could preclude its use altogether as infarct volume can be calculated from follow-up imaging which also correlates with developing mMCAi.