Abstract P1162: Cardiac Magnetic Resonance Imaging Measures of Atrial Cardiomyopathy and Adverse Clinical Outcomes in the UK Biobank

Introduction: Atrial cardiomyopathy precedes atrial fibrillation (AF) and is a strong risk factor for downstream adverse clinical outcomes, but there is no census about the optimal method for assessing it. Cardiac magnetic resonance imaging (CMR) is the most accurate tool to assess atrial function and structure. Our objective was to evaluate the association between CMR measures of atrial cardiomyopathy, incident AF, and AF-related clinical complications. Hypothesis: We hypothesized that CMR measures of atrial cardiomyopathy are associated with AF, ischemic stroke, heart failure, and dementia, independent of established risk factors. Methods: In 44,591 participants who underwent CMR as part of UK Biobank Imaging Study and had no history of AF, we assessed atrial minimal and maximal volumes (indexed to body surface area) and ejection fraction. Cox proportional hazard models were used to evaluate the association of these CMR measures with incident AF, ischemic stroke, heart failure, and dementia, adjusting for established risk factors. Results: During a median follow-up time of 4.0 [IQR 2.9-5.4] years, 834 (2%) participants developed AF, 197 (0.4%) developed ischemic stroke, 278 (0.6%) developed heart failure, and 61 (0.1%) developed dementia. The mean [standard deviation] age was 65 [8] years and 51% were female. When evaluated as continuous variables, left atrial ejection fraction (LAEF) was significantly associated with the risk of new-onset AF, ischemic stroke, and heart failure, while left atrial minimal volume (LAVI min ) and maximal volume (LAVI max ) were associated with these outcomes as well as the risk of dementia (Table). In comparison, right atrial measures were associated with only AF and heart failure, and the magnitude of the associations was generally smaller. After further adjustment for time-varying AF, these associations remained significant. When categorized by quintiles, participants in the highest LAVI min group had a HR of 3.67(95%CI 2.93-4.60) for AF, 1.51(95%CI 1.02-2.25) for ischemic stroke, 2.71(95%CI 1.86-3.96) for heart failure, and 2.43 (95%CI 1.11-5.31) for dementia, compared to those in the lowest. Conclusion: CMR measures of atrial structure and function were associated with AF-associated clinical outcomes independent of risk of AF. These findings suggest that atrial cardiomyopathy may be an important target of future research efforts, with potential implications for screening patients at high risk for cardiovascular disease.