An assessment of diagnosis and prognostication in cardioembolic transient ischaemic attack and ischaemic stroke

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Lyons, Shane M.
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University College Cork
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Transient ischaemic attack (TIA) and ischaemic stroke is a heterogeneous disease with more than 150 known causes with different profiles of vascular risk factors and recurrence risk. Cardioembolic events account for approximately a third of incident stroke. The aim of my thesis has been to assess current methods of identifying cardioembolic source of TIA and stroke, examine the prevalence of atrial fibrillation as the most important cause of cardioembolic neurovascular events as well as the predictors and risk factors of AF in this population. I aimed to test strategies for targeting cardiac investigations using clinical, imaging and echocardiographic parameters, evaluate the clinical significance of cardiac monitoring results, and improve prognostication in cardioembolic events to facilitate optimal treatment. I have collected, collated and analysed data from the Oxford Vascular Study (OXVASC), which is an ongoing prospective, population-based, incidence study of vascular disease in all territories in Oxfordshire, UK. The study population comprises approximately 92,728 individuals registered with nine general practices and uses multiple overlapping “hot” and “cold” methods to identify all patients with acute vascular events. There are several clinically relevant findings in this thesis which address areas of investigation and management of cardioembolic events. First, I have assessed the role of cardiac monitoring following TIA and minor stroke, establishing the prevalence of occult AF in the OXVASC population and evaluating the yield of different monitoring duration in the published literature. Second, I found that a score, the ABC2 score, derived from well established risk factors could improve the yield of cardiac monitoring. Third, I have demonstrated a low risk of recurrent neurovascular and systemic embolic events in patients with brief paroxysms of AF on monitoring in the study population. Fourth, I have shown that copeptin can identify subgroup of patient at particularly high risk of recurrent cardioembolic neurovascular events and that this risk is ameliorated by oral anticoagulant treatment. Fifth, I have demonstrated that the risk of progression of brief paroxysms of AF, while still significant, is lower than previously suspected. Finally, there is a significant incidence of AF during medium-term follow-up after stroke and TIA, suggesting that screening targeted at this population may be of use in risk modification.
Stroke , Cardioembolism
Lyons, S. M. 2019. An assessment of diagnosis and prognostication in cardioembolic transient ischaemic attack and ischaemic stroke. MD Thesis, University College Cork.
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