Clinical StudyShorter time to intervention improves recanalization success and clinical outcome post intra-arterial intervention for basilar artery thrombosis
Introduction
Acute basilar artery thrombosis represents from 1% to 4% of all ischaemic strokes.[1], [2], [3] It is a catastrophic subtype of posterior circulation ischaemic stroke which is associated with an 80% to 90% mortality rate in the absence of treatment.[4], [5], [6] Successful recanalization of an occluded artery is associated with better outcomes.[7], [8] However, due to the low rates of successful recanalization of occluded basilar arteries by intravenous (IV) thrombolytics (30%),9 intra-arterial (IA) interventions are justified.4
IA interventions have been shown to be efficacious in their ability to achieve high recanalization rates,[10], [11] leading to lower mortality rates and better functional outcomes.[12], [13] Only one multicentre randomized controlled trial has assessed the efficacy of IA therapy for acute basilar thrombosis. The Australian Urokinase Stroke Trial (AUST) recruited 16 patients over 7 years, randomised into either the treatment or placebo group.[14], [15] Good neurological outcomes were more frequently observed in the treatment group (50%) than in the placebo group (12.5%).15 Independent variables affecting survival were shown to include collateral state and age,16 thrombus volume and pre-treatment morbidity,17 and Glasgow Coma Scale (GCS) score.18
The recanalization rate for individual patients is not uniform. It may be that the longer the delay to intervention from stroke onset, the lower the chances of achieving successful recanalization. However, this has yet to be validated. A theory has been proposed that the clot composition changes with time. Fresh newly formed clots are more red blood cell dominant and less resistant to thrombolysis, while older clots are more fibrin-rich and well-organized and hence more resistant to thrombolysis.[19], [20], [21], [22] Furthermore, shortening the delay to intervention is vital in ensuring the survival of penumbral tissue.23 Successful intervention to attenuate the growth of the ischaemic core positively contributes to good clinical outcomes.[24], [25], [26] Survival of penumbra tissue relies on achieving successful recanalization of occluded arteries, which may be limited by delay to initiation of IA intervention.
In this study, we aim to determine if time to treatment is a predictor of recanalization success. We hypothesize that early intervention significantly improves recanalization success.
Section snippets
Methods
This is a retrospective single centre review of 49 consecutive patients with confirmed acute basilar artery thrombosis who received IA intervention between 1993 and 2011. Patients who presented within 24 hours of symptom onset were offered IA therapy following confirmation of basilar artery thrombosis by digital subtraction angiography (DSA). Exclusion criteria were: established extensive infarction on pre-operative CT scan, intracranial haemorrhage and patients presenting more than 24 hours post
Results
Of the 49 patients, the mean age was 59.8 years ± 17.9, 36.7% were females and mean GCS score was 9.5 ± 4.4. Baseline characteristics, vascular risk factors, clinical presentation and key angiographic and clinical data are presented in Table 1.
Discussion
The natural history of acute basilar artery thrombosis managed with antiplatelet and/or anticoagulant therapy is poor.[9], [30] Hacke et al. reported a mortality rate of 86% in a cohort of 22 patients who received antiplatelet or anticoagulant therapy,9 while Schonewille et al. reported a mortality rate of 40% in a cohort of 82 patients and a dependency rate (mRS 4–5) of 65% in a similar subgroup of patients.30 Coupled with the low spontaneous recanalization rate in patients with acute basilar
Conclusion
Our study suggests that early intervention improves the likelihood of achieving recanalization success and good clinical outcome post IA intervention in basilar artery thrombosis. We propose a need for hospital system implementations to minimize the delay to treatment.
Conflict of interest/disclosures
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
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