Transcranial Doppler ultrasonography predicts cardiovascular events after TIA

<p>Abstract</p> <p>Background</p> <p>Transient ischemic attack (TIA) patients are at high vascular risk. We assessed the value of extracranial (ECD) and transcranial (TCD) Doppler and duplex ultrasonography to predict clinical outcome after TIA.</p> <p>Methods</p> <p>176 consecutive TIA patients admitted to the Stroke Unit were recruited in the study. All patients received diffusion-weighted imaging, standardized ECD and TCD. At a median follow-up of 27 months, new vascular events were recorded.</p> <p>Results</p> <p>22 (13.8%) patients experienced an ischemic stroke or TIA, 5 (3.1%) a myocardial infarction or acute coronary syndrome, and 5 (3.1%) underwent arterial revascularization. ECD revealed extracranial ≥ 50% stenosis or occlusions in 34 (19.3%) patients, TCD showed intracranial stenosis in 15 (9.2%) and collateral flow patterns due to extracranial stenosis in 5 (3.1%) cases. Multivariate analysis identified these abnormal ECD and TCD findings as predictors of new cerebral ischemic events (ECD: hazard ratio (HR) 4.30, 95% confidence interval (CI) 1.75 to 10.57, P = 0.01; TCD: HR 4.73, 95% CI 1.86 to 12.04, P = 0.01). Abnormal TCD findings were also predictive of cardiovascular ischemic events (HR 18.51, 95% CI 3.49 to 98.24, P = 0.001).</p> <p>Conclusion</p> <p>TIA patients with abnormal TCD findings are at high risk to develop further cerebral and cardiovascular ischemic events.</p

Prognostic value of clinical neuroimaging in the investigation of minor ischaemic stroke and transient ischaemic attack

Stroke is the largest cause of adult neurological disability in the UK and up to 40% of disabling strokes are preceded by a minor ischaemic stroke or transient ischaemic attack (TIA). As the prompt initiation of preventative therapy can reduce the risk of recurrent stroke by up to 80%, there is a need for highly organised services and optimised secondary prevention therapies. Neuroimaging is fundamental to the investigation of cerebrovascular events and, when coupled with prognostic information, can contribute to tailored secondary prevention therapy. In this thesis, I aimed to provide new insights into the role of neuroimaging in the prognostication of minor ischaemic stroke and TIA, in order to assist clinical decision making and patient counselling. Data used in this thesis have been obtained from the Oxford Vascular Study (OXVASC); an ongoing prospective, population-based incidence study of vascular disease in Oxfordshire, operational since 1st April 2002. The OXVASC population comprises around 93,000 individuals, predominately Caucasian, defined by registration with one of nine primary care practices. Multiple overlapping methods are used to identify all patients with acute vascular events. Patients consecutively recruited to OXVASC with minor ischaemic stroke or TIA, irrespective of age, were included. All imaging was performed at the John Radcliffe Hospital and was with magnetic resonance imaging (MRI)/ MR-angiogram, or computed tomography (CT)/ CT-angiogram if MRI was contraindicated. I reviewed all imaging blinded to the report of the study neuroradiologist. I report several key findings in this thesis. First, intracranial atherosclerotic stenosis (ICS) was found in 19% of patients with the highest rates at older ages (21.2% at age ≥90 years). Although symptomatic ICS conveyed an increased risk of ischaemic stroke compared to no ICS (adjusted hazard ratio [HR]= 2.1, 95% CI 1.1- 3.7), the risks of same-territory ischaemic stroke in patients with 70- 99% symptomatic ICS tended to be less than those reported in the non-stenting arms of the trials, validating the role of intensive medical management in routine clinical practice. Asymptomatic ICS did not convey additional risk of vascular events or death. Second, diffusion-weighted imaging (DWI) lesions predicted an increased risk of recurrent ischaemic stroke after minor ischaemic stroke with NIHSS 0-1 and TIA up to 10 years (HR= 3.0, 1.3- 7.1 and 2.7, 1.3- 5.5, respectively), and the strongest predictive value was in patients with a cryptogenic aetiology (HR= 4.7, 1.7- 12.9). Third, 5% of patients referred to an acute neurovascular clinic harbour an asymptomatic, incidental unruptured intracranial aneurysm. Although this is almost double the rate in the general population, the subsequent risk of aneurysm rupture was low (4.6 subarachnoid haemorrhages per 1,000 person-years) in the context of intensively managed vascular risk factors and guideline-based surveillance and intervention