PS-C35-4: ASSOCIATION OF SODIUM INTAKE WITH ADVERSE LEFT ATRIAL FUNCTION AND LEFT ATRIOVENTRICULAR COUPLING

Abstract

Objective: In this study, we investigated the relationship between 24-hour urinary sodium (a surrogate for estimating dietary sodium intake), ambulatory blood pressure parameters, cardiac MRI-assessed left atrial function and left atrioventricular coupling, as well as the influence of nighttime blood pressure and body mass index(BMI) on 24-hour urinary sodium and subclinical cardiac function. Design and method: Participants in our study included 398 individuals, all of whom were subjected to 24-hour urine collection, 24-hour ambulatory blood pressure measurement, and cardiac magnetic resonance imaging to determine left atrial function (myocardial strain) as well as left atrioventricular coupling index. LACI is defined as the ratio of left atrial end-diastolic volume divided by left ventricular end-diastolic volume. Our study evaluated the relationship between 24-hour urinary sodium and ambulatory blood pressure parameters, left atrial function, and left atrioventricular coupling index, and used mediation analysis to explain the indirect effects of nighttime blood pressure and BMI between 24-hour urinary sodium and left atrial function and left atrioventricular coupling index. Results: It was found that the average age of the participants was 55.70 ± 11.30 years old, with 58% of the participants being male and 47.5% experiencing hypertension. The mean urinary sodium value was 172.01 ± 80.24mmol/24 hours, and the average body mass index was 25.46 ± 3.78 kg/m2. After adjusting for age, gender, history of diabetes, smoking status, alcohol consumption, and use of diuretics, 24-hour urinary sodium was correlated with multiple ambulatory blood pressure parameters, especially with nighttime diastolic blood pressure. Left atrial structure and function (left atrial reservoir function and left atrial conduit function) and left atrioventricular coupling index were correlated (P < 0.05). Mediation analysis showed that BMI explained 16% of the indirect effect of 24-hour urinary sodium and left atrial function (left atrial reservoir function and left atrial conduit function), and 30% of the indirect effect of LACI. Independent of the mediator, 24-hour urinary sodium had a significant direct effect on left atrial reservoir function, left atrial conduit function, and left atrioventricular coupling. Conclusions: Higher 24-hour urinary sodium was associated with a greater BMI as well as poor left atrial function and left atrioventricular coupling, and the BMI mediated the relationship between 24-hour urinary sodium and subclinical left cardiac function, and, more importantly, 24-hour urinary sodium may directly affect the left atrial function and left atrioventricular coupling independent of intermediary factors.