London, United Kingdom 2013 15 Etiology of stroke and risk factors B 17:20 - 17:30 Impact of stroke classification systems on strength of genetic associations with ischaemic stroke O. Parsons1, M. Traylor2, L. Linxin3, S. Bevan4, C. Sudlow5, P.M. Rothwell6, C. Levi7, H.S. Markus8 Stroke and Dementia Research Centre, St. George’s University London, London, UNIT-ED KINGDOM1,Stroke and Dementia Research Centre, St. George’s University London, Lon-don, UNITED KINGDOM2, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UNITED KINGDOM3, Stroke and Dementia Research Centre, St. George’s University London, London, UNITED KINGDOM4, Division of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, Edinburgh, UNITED KINGDOM5, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospi-tal, University of Oxford, Oxford, UNITED KINGDOM6, Priority Centre for Brain & Mental Health Research, University of Newcastle and Hunter Medical Research Institute, Newcastle, AUSTRALIA7, Stroke and Dementia Research Centre, St. George’s University London, Lon-don, Cerebrovasc Dis 2013; 35 (suppl 3)1-854 75 UNITED KINGDOM8 Background The genome wide association study approach (GWAS) has recently identified sev-eral novel genetic variants which increase risk of ischaemic stroke. To date all these confer risk of specific stroke subtypes making accurate stroke subtyping vital. The Trial or Org 10172 in Acute Stroke Treatment (TOAST) classification system has been used in studies to date. The Causative Classification of Stroke (CCS) system may have higher accuracy and could increase power in GWAS studies. To assess the added value of using CCS we compared effect sizes for known variants, where patients were classified using both TOAST and CCS. Methods Data on 2374 cases and 5175 controls were used. Cohorts were obtained from WTC-CC2- UK ischaemic stroke GWAS (St George’s London, Oxford and Edinburgh) and all cas-es were originally classified using TOAST. Effect sizes for the following variants, previously associated with cardioembolic (CE) and large vessel (LVD) stroke, were compared: HDAC9, PITX, 9p21, ABO, ZFHX3, 6p21.1. Comparisons were made between effect sizes in associa-tion analyses using CCS or TOAST classifications for 238 LVD and 505 CE cases. Results Effect sizes calculated under CCS classification only differed slightly from those cal-culated under TOAST. For LVD associated SNPs, effect sizes under CCS tended to be slightly larger than under TOAST with HDAC9 showing the largest reduction (37.6%) in required sam-ple size for 80% power under CCS. Conversely, CCS classification led to a smaller effect sizes for CE associated SNPs with ZFHX3 showing the greatest increase (144%) in required sample size. Conclusions Reclassification under CCS led to only minor changes in effect sizes with contrast-ing direction of change for LVD and CE, suggesting it does not universally lead to increased power in analyses. Future classification using CCS offers advantages such as recording of clin-ical information used to subtype, but reclassification of TOAST classified cases is unlikely to lead to major increases in power. 14 Etiology of stroke and risk factors B 17:10 - 17:20 Therapeutic impact of transesophageal echocardiography in the diagnostic work-up of patients with ischemic stroke or TIA L.P. Pallesen1, M. Ragaller2, J. Keppliger3, I. Dzialowski4, K. Barlinn5, A.C. Zerna6, B. Wie-demann7, U. Bodechtel8, V. Puetz9 Dresden University Stroke Center, Department of Neurology, Dresden Technical Uni-versity, Dresden, GERMANY1,Dresden University Stroke Center, Department of Neurolo-gy, Dresden Technical University, Dresden, GERMANY2, Dresden University Stroke Center, Department of Neurology, Dresden Technical University, Dresden, GERMANY3, Dresden University Stroke Center, Department of Neurology, Dresden Technical University, Dresden, GERMANY4, Dresden University Stroke Center, Department of Neurology, Dresden Technical University, Dresden, GERMANY5, Dresden University Stroke Center, Department of Neurolo-gy, Dresden Technical University, Dresden, GERMANY6, Institute for Medical Informatics and Biometry, Dresden Technical University, Dresden, GERMANY7, Dresden University Stroke Center, Department of Neurology, Dresden Technical University, Dresden, GERMANY8, Dres-den University Stroke Center, Department of Neurology, Dresden Technical University, Dres-den, GERMANY9 Background Besides atrial fibrillation, several other conditions like patent foramen ovale (PFO) or aortic plaque are discussed as sources of cardiogenic emboli. Transesophageal echocardiography (TEE) is considered superior towards transthoracic echocardiography (TTE) for detection of these conditions. We analyzed the therapeutic impact of additional TEE compared with TTE in patients with ischemic stroke or transient ischemic attack (TIA). Methods We retrospectively analyzed consecutive patients with ischemic stroke or TIA who presented to our tertiary care stroke center between 2009 and 2012. All patients who did not have atrial fibrillation underwent TTE followed by TEE as part of a standardized diagnostic work-up for stroke etiology. We assessed clinical baseline characteristics, diagnostic findings of TEE studies and final medical secondary prophylaxis. Our primary endpoint was any change of the medical secondary prophylaxis due to TEE. Results Of 791 patients (mean age 64+/-13 years, median baseline NIHSS-score 2 (mean 3.32, CI95% 2.96-3.69), 589 (74%) ischemic stroke, 202 (26%) TIA), the result of the TEE study caused a change of the medical secondary prophylaxis in 71 patients (9%). Main findings which result-ed in changes of medical therapy were PFO with atrial septal aneurysm (34%), complex aortic plaque (24%) and aortic thrombi (8%). Main medical changes were initiation of oral anticoagu-lants (n=49, 69%) or low weight molecular heparin (n=8, 11%). In univariate analysis, periph-eral vascular disease (p=0.038) and therapy with clopidogrel at the time of the cerebral isch-emic event (p=0.04) were associated with change of secondary prophylaxis due to diagnostic TEE findings. Conclusion Diagnostic findings in the TEE resulted in changes of medical secondary prophylaxis in 9% of our patients. Pre-exisiting vascular co-morbidities may identify patients who benefit from addi-tional TEE as part of the diagnostic work up for stroke etiology.
Karger_ESC London_2013
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