Role of Sodium Levels on Atrial Fibrillation in Heart Failure: Active Player or a Bystander?

Abstract

Background: The coexistence of hyponatremia and atrial fibrillation (AF) increases morbidity and mortality in patients with heart failure (HF). However, it is not established whether hyponatremia is related to AF or not. Objective: Our study aims to seek a potential association of hyponatremia with AF in patients with reduced ejection fraction heart failure (HFrEF). Methods: This observational cross-sectional single-center study included 280 consecutive outpatients diagnosed with HFrEF with 40% or less. Based on sodium concentrations <= 135 mEq/L or higher, the patients were classified into hyponatremia (n=66) and normonatremia (n=214). A p-value <0.05 was considered significant. Results: Mean age was 67.6 +/- 10.5 years, 202 of them (72.2%) were male, mean blood sodium level was 138 +/- 3.6 mEq/L, and mean ejection fraction was 30 +/- 4%. Of those, 195 (69.6%) patients were diagnosed with coronary artery disease. AF was detected in 124 (44.3%) patients. AF rate was higher in patients with hyponatremia compared to those with hyponatremia (n=39 [59.1%] vs. n=85 [39.7%), p= 0.020). In the logistic regression analysis, hyponatremia was not related to AF (OR=1.022, 95% CI=0.785-1.330, p=0.871). Advanced age (OR=1.046, 95% CI=1.016-1.177, p=0.003), presence of CAD (OR=2.058, 95% CI=1.122-3.777, p=0.020), resting heart rate (OR=1.041, 95% CI=1.023-1.060, p<0.001), and left atrium diameter (OR=1.049, 95% CI=1.011-1.616, p=0.002) were found to be predictors of AF. Conclusion: AF was higher in outpatients with HFrEF and hyponatremia. However, there is no association between sodium levels and AF in patients with HFrEF.