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Left ventricular structure and function in relation to sodium dietary intake and renal handling in untreated Chinese
Yi-Bang Cheng1, Chak-Ming Chan1, Ting-Yan Xu1
1Department of Cardiovascular Medicine, Centre for Epidemiological Studies and Clinical Trials, Shanghai Key Laboratory of Hypertension, The Shanghai Institute of Hypertension, National Research Centre for Translational Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
Insights
Dietary sodium intake and kidney sodium handling influence left ventricular structure, particularly in individuals with specific kidney sodium handling characteristics. Blood pressure also plays a role in left ventricular mass index.
Area of Science:
- Cardiology
- Nephrology
- Hypertension Research
Background:
- The relationship between dietary sodium, renal sodium handling, and left ventricular (LV) structure and function, considering blood pressure (BP), is not fully understood.
- Left ventricular hypertrophy (LVH) is a significant risk factor for cardiovascular events.
- Urinary sodium excretion and tubular sodium handling are key determinants of sodium balance and BP.
Purpose of the Study:
- To investigate the association of dietary sodium intake and renal sodium handling with left ventricular structure and function.
- To explore the interplay between sodium excretion, renal sodium handling, and blood pressure in relation to left ventricular parameters.
Main Methods:
- Recruitment of 952 untreated patients undergoing ambulatory BP monitoring.
- Echocardiography to assess left ventricular structure and function.
- Calculation of fractional excretion of lithium (FELi) and fractional distal reabsorption rate of sodium (FDRNa) as markers of proximal and distal tubular sodium handling.
Main Results:
- Significant interactions were found between urinary sodium excretion and FELi concerning left ventricular posterior wall thickness (LVPW), mass (LVM), and mass index (LVMI).
- Urinary sodium excretion was significantly associated with LVPW, LVM, and LVMI only in the lowest tertile of FELi.
- In mutually adjusted analyses, LVMI was significantly associated with FELi, FDRNa, and 24-h systolic BP. Sodium renal handling indexes, similar to 24-h BP, were associated with LVMI.
Conclusions:
- Dietary sodium intake and renal handling interact to influence left ventricular structure.
- Renal handling indexes are independently associated with left ventricular mass index, similar to 24-hour blood pressure.
- These findings highlight the complex interplay between sodium balance, renal function, and cardiac remodeling.
Abstract:
Whether left ventricular structure and function is associated with sodium dietary intake and renal handling while considering blood pressure (BP) remains unclear. Consecutive untreated patients referred for ambulatory BP monitoring were recruited. Standard echocardiography was performed to measure left ventricular structure and function. Fractional excretion of lithium (FELi) and fractional distal reabsorption rate of sodium (FDRNa) were calculated as markers of proximal and distal tubular sodium handling, respectively. The 952 participants (51.0% women; mean age, 50.8 years) included 614 (64.5%) ambulatory hypertension and 103 (10.8%) left ventricular hypertrophy. There were significant interactions of urinary sodium excretion with FELi (P ≤ 0.045), but not FDRNa (P ≥ 0.36), in relation to left ventricular posterior wall thickness (LVPW), mass (LVM) and mass index (LVMI), but not functional measurements. Only in tertile 1 of FELi, the multivariate-adjusted regression coefficients for urinary sodium excretion reached statistical significance (P ≤ 0.049), being 0.16 ± 0.05 mm, 4.32 ± 1.48 g, and 1.64 ± 0.83 g/m2 for LVPW, LVM and LVMI, respectively. In mutually adjusted analyses, the regression coefficient for LVMI was statistically significant for FELi, FDRNa and 24-h systolic BP, being -2.17 ± 0.49, -1.95 ± 0.54, and 2.99 ± 0.51 g/m2, respectively (P < 0.001). Multivariable analysis of variance showed that sodium renal handling indexes (P ≥ 0.14), but not sodium urinary excretion (P = 0.007), were similarly as 24-h BP associated with LVMI. Heat maps on left ventricular hypertrophy provided a graphical confirmation of the findings. Sodium dietary intake and renal handling interact to be associated with left ventricular structure. Renal handling indexes were similarly in size as, jointly in action with and independently of 24-h BP.
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