Differences in Factors Predicting Outcome and Mortality after Mechanical Thrombectomy for Acute Large Vessel Stroke Between Patients over and Under 70 Years of Age: A Five Year Retrospective Study

Abstract

Aim: To assess the differences in risk factors between different age groups after mechanical thrombectomy (MT) for ischaemic stroke, including recanalization time and functional and radiological scoring.

Methods: Patients treated between December 2009 and January 2014 (n=137) for anterior circulation stroke were divided into age groups. Patient data including National Institutes of Health Stroke Scale (NIHSS) and Alberta Stroke Program Early CT Score (ASPECTS) scoring pre and post procedure and procedural timings were collected. Modified Rankin score was used as functional outcome measure at 90 days.

Results: For the >70 age group, ASPECTS correlated most strongly with outcome (ASPECTS >7 - OR 3.75, 95% CI 1.04-13.5) and mortality (ASPECTS <8 - OR 5.08, CI 1.1-23.3). In the <70 age group, only NIHSS correlated with both outcome (NIHSS <20 – OR 4.17, CI 1.4-12.2) and mortality (NIHSS >20 – OR 6.22, CI 1.4-26.7) (p<0.05). Both NIHSS and ASPECTS done at 24h were strongly associated with outcome at 90 days. Revascularisation >5h after onset in the <70 age group was associated with markedly poorer outcome with increased risk of malignant MCA transformation, while this trend was not seen in the >70 age group.

Conclusions: ASPECT scoring at admission is clinically helpful in patient selection for thrombectomy in the >70 age group as it correlates well with outcome and mortality, but less useful in the <70 age group, possibly due to the increased plasticity of remodelling. Revascularisation time appears to be much more important in the younger age group, and restoration of circulation within 5 hours should be the goal to reduce the risk of reperfusion injury.