Middle age serum sodium levels in the upper part of normal range and risk of heart failure.

Abstract

With increasing prevalence of heart failure (HF) owing to the ageing population, identification of modifiable risk factors is important. In a mouse model, chronic hypohydration induced by lifelong water restriction promotes cardiac fibrosis. Hypohydration elevates serum sodium. Here, we evaluate the association of serum sodium at middle age as a measure of hydration habits with risk to develop HF. We analysed data from Atherosclerosis Risk in Communities study with middle age enrolment (45-66 years) and 25 years of follow-up. Participants without water balance dysregulation were selected: serum sodium within normal range (135-146 mmol/L), not diabetic, not obese and free of HF at baseline (N = 11 814). In time-to-event analysis, HF risk was increased by 39% if middle age serum sodium exceeded 143 mmol/L corresponding to 1% body weight water deficit [hazard ratio 1.39, 95% confidence interval (CI) 1.14-1.70]. In a retrospective case-control analysis performed on 70- to 90-year-old attendees of Visit 5 (N = 4961), serum sodium of 142.5-143 mmol/L was associated with 62% increase in odds of left ventricular hypertrophy (LVH) diagnosis [odds ratio (OR) 1.62, 95% CI 1.03-2.55]. Serum sodium above 143 mmol/L was associated with 107% increase in odds of LVH (OR 2.07, 95% CI 1.30-3.28) and 54% increase in odds of HF (OR 1.54, 95% CI 1.06-2.23). As a result, prevalence of HF and LVH was increased among 70- to 90-year-old participants with higher middle age serum sodium. Middle age serum sodium above 142 mmol is a risk factor for LVH and HF. Maintaining good hydration throughout life may slow down decline in cardiac function and decrease prevalence of HF.