Abstract 23: Neuroimaging and Echocardiographic Predictors of Paroxysmal Atrial Fibrillation on Outpatient Mobile Cardiac Outpatient Telemetry in Cryptogenic Ischemic Stroke and TIA Patients

Background: The objective of our study was to identify factors on MRI neuroimaging and echocardiography as part of routine workup of patients with cryptogenic ischemic stroke (IS) or transient ischemic attack (TIA) to identify those patients who are likely to have paroxysmal atrial fibrillation (PAF) as detected by subsequent outpatient mobile cardiac outpatient telemetry (MCOT). Methods: All cryptogenic IS or TIA patients seen at Emory University Hospital and The Emory Clinic from 2009-2013 and who underwent outpatient MCOT were included in this analysis.Using logistic regression, we analyzed the association between lesions seen on MRI FLAIR sequences with PAF and categorized them as the following: Cortical lesions (CL), defined as T2-hyperintense cortical-based infarcts; high subcortical (HS) T2-hyperintense lesions, defined as <5mm beneath the cortex without any cortical involvement, or none. Left atrium (LA) functional and dimensional echocardiographic parameters were evaluated to determine their association with PAF. Results: Of 132 patients included in this analysis, 17 (13%) had evidence of newly diagnosed PAF on MCOT (mean duration of monitoring=25 days); median age was 72 (IQR: 64-79), 50% were women, diabetes was present in 23%, hypertension in 76%, dyslipidemia in 64%, and active tobacco use in 8%. CL seen on baseline MRI were found to be significant predictors of PAF (OR 5.2, 95 % CI: 1.3-19; p=0.01). HS lesions were not found to be a significant predictor of PAF. On baseline echocardiography, patients who had PAF (vs non-PAF) had significantly higher mean LA diameter (4.2 vs 3.7 cm, p=0.03), lower tissue Doppler velocity (a’) (5.5 vs 13.5 cm/s, p=0.03), a trend toward higher left atrium volume index (LAVI) (37.5 vs 29.2, p=0.07) and mean LAVI/late diastolic Doppler velocity (A) (0.67 vs. 0.37, P= 0.006). The Areas under the Curve (AUC) for the parameters were: LA diameter 71.4%, a’ 92.6%, LAVI 74.6%, LAVI/A 62.5%, LAVI/a’ 67.9%. Conclusion: Cortical-based infarcts seen on MRI FLAIR sequences and baseline echocardiographic variables may help to predict cryptogenic ischemic stroke or TIA patients who are likely to have PAF identified on outpatient MCOT.