Assessing Left Atrial Volume Indexation to Predict Mortality in Individuals With Overweight and Obesity

BACKGROUND: Alternative indexation methods for left atrial volume (LAV) have been proposed to achieve better proportional scaling than the current standard body surface area indexation. However, there are limited data showing that these alternative indices provide long-term prognostic value in individuals with overweight or obesity. The aim of this study was to determine and compare the performance of various LAV indexation methods in predicting all-cause mortality in individuals with overweight or obesity. METHODS: We obtained data from the National Echocardiography Database Australia with linkage to mortality outcomes, selecting individuals with body mass index ≥25 kg/m 2 and valid LAV, height, weight, and left ventricular ejection fraction. We conducted receiver operating characteristic analyses, including area under the curve calculations, to compare the performance of 9 LAV indices in predicting all-cause mortality. In addition, we performed a survival analysis between LAV and all-cause mortality. RESULTS: A total of 109 543 individuals (age 60±16 years, 47% women) were included. Indexing LAV by most methods performed similarly in predicting all-cause mortality, with areas under the curve between 0.60 and 0.62 ( P <0.05), except that LAV and LAV/body mass index had the lowest area under the curve with 0.600 (0.595–0.604) and 0.602 (0.597–0.606). Indexation methods also performed similarly when separated by age, sex, or follow-up duration. A mortality threshold for LAV/body surface area was observed at 34 mL/m 2 , with no difference by sex. CONCLUSIONS: Among patients with overweight or obesity, the majority of LAV indices performed similarly in predicting all-cause mortality. Our findings support the continued use of LA volume indexed to body surface area for prognosis in this population, and the current normal range of <34 mL/m 2 . REGISTRATION: URL: https://anzctr.org.au/Default.aspx ; Unique identifier: ACTRN12617001387314.