Introduction:
Acute ischemic strokes affecting the posterior circulation (PC) present with distinct clinical, radiological, and prognostic characteristics compared to anterior circulation (AC) strokes. While revascularization treatment has been extensively studied in the AC, there is still a lack of evidence from randomized clinical data for PC strokes. Furthermore, the efficacy of endovascular treatment (EVT) for PC strokes in arterial sites other than BAO is not well-established, with some retrospective analyses even suggesting potential harm. This study aimed to: 1) elucidate the clinical-radiological profile of PC strokes, 2) identify clinical and radiological predictors of medium-term functional outcome in PC strokes, and 3) investigate the response to revascularization treatment for isolated vertebral artery occlusions (iVAO).
Methods:
The study was structured into three sections: 1) a comprehensive literature review emphasizing the clinical-radiological characteristics of PC strokes and their response to acute revascularization; 2) the development and internal validation of two outcome prediction models, namely the PC-ASTRAL and PC-CBS scores; and 3) a retrospective analysis of revascularization outcomes for iVAO using data from a large multicentre consortium.
Results:
Literature on peculiarities of PC strokes and PC occlusions was presented in detail. Two predictive models were developed: a) the PC-ASTRAL score, a clinical-radiological model applicable to all PC strokes irrespective of occlusion presence, with an AUC of 0.85 (0.77-0.92); and b) the PC-CBS score, a radiological model developed for strokes associated with large or medium vessel occlusions in the PC, which yielded an AUC of 0.70, improving to 0.85 upon integrating clinical variables. The evaluation of revascularization outcomes for iVAO revealed notably more unfavourable outcomes for people undergoing EVT compared to those receiving best medical treatment and a non-significant yet positive trend towards potential benefits of IVT over conservative treatment.
Conclusion:
The PC-ASTRAL and PC-CBS scores may offer valuable information for patient stratification and guiding treatment decisions. Nonetheless, they still need to complete the still ongoing external validation process. The findings from the BRAVO study can inform the design and cohort selection for future randomized clinical trials focusing on iVAO.