343 Atrial Fibrillation, Orthostatic Hypotension and Cerebral Perfusion – Data from The Irish Longitudinal Study on Ageing

Abstract

Abstract Background It is thought that cerebral hypoperfusion in Atrial Fibrillation (AF) increases the risk of falls, cognitive impairment, and worse outcome in stroke. This aim of this study is to assess frontal lobe perfusion in response to active stand, and to assess the impact of OH on this association. Methods Data from wave 3 of The Irish Longitudinal Study on Ageing were used, a cohort study of community-dwelling adults aged over 50. Frontal lobe perfusion in response to orthostasis was measured using near infra-red spectroscopy (NIRS), reported as tissue saturation index (TSI%). Orthostatic hypotension (OH) was assessed using beat-to-beat blood pressure measurement. Linear regression assessed whether AF was associated with lower baseline TSI. Mixed effects linear regression assessed whether TSI differed across specific time points – 10, 20, 30, 40 60, 90, and 120 seconds. The analysis were repeated including an interaction with OH to assess the impact of OH on this association. Results There was no difference in baseline TSI in participants with AF compared to those without. Mixed effects models demonstrated lower TSI at 10 seconds in AF (β -0.52; 95% CI -0.88, -0.16; p-value 0.004), at 40 seconds (β -0.40; 95% CI -0.76, -0.04; p-value 0.031) and at 60 seconds (β -0.40; 95% CI --0.76, -0.04; p-value 0.028). Including an interaction with OH found that in isolated AF, TSI was lower at 10 seconds (β -0.62; 95% CI -1.04, -0.19; p-value 0.005). Those with both AF and OH had lower TSI at 40 (β -0.89; 95% CI -1.55, -0.24; p-value 0.007), 60 (β -0.89; 95% CI -1.54, -0.23; p-value 0.008) and 90 (β -0.68; 95% CI -1.33, -0.03; p-value 0.041) seconds. Conclusion There is evidence that frontal lobe perfusion is lower during orthostasis in individuals with AF, and that the presence of OH modifies this association.