Influence of Dietary Sodium Modulation on Electrocardiographic Voltage Criteria for Left Ventricular Hypertrophy in Normotensive Individuals

OBJECTIVE: Dietary sodium intake and left ventricular hypertrophy (LVH) on electrocardiogram (ECG) are both independent determinants of cardiovascular risk. Prior studies demonstrated that acute dietary sodium modulation significantly altered LVH-specific ECG voltage in hypertensive individuals, thus modifying cardiovascular risk prediction; but whether this phenomenon exists in normotensive individuals is not known. We evaluated the influence of dietary sodium intake on ECG voltage and ECG criteria for LVH in normotensive individuals. METHODS: Retrospective evaluation of ECGs of healthy normotensive individuals (n = 39) who were prospectively randomized to a dietary study protocol of 1 week of high-sodium diet (>200 mmol of sodium per day) and 1 week of low-sodium diet (<10 mmol/d) was conducted. Electrocardiogram voltage amplitudes and biochemical assessments were performed at the end of each dietary intervention. RESULTS: As expected, blood pressure declined and measures of circulating renin-angiotensin-aldosterone system activity rose significantly with low-sodium diet. No significant changes in specific LVH voltage criteria or overall precordial or limb lead ECG voltage amplitudes were detected between diets. CONCLUSION: Although immediate dietary sodium modulation has been shown to significantly alter LVH-specific ECG voltage and the detection of LVH in hypertensive individuals, dietary sodium intake did not influence ECG voltage in normotensive individuals. Healthy normotensive individuals may exhibit adaptive measures that dampen ECG voltage fluctuations in response to dietary sodium modulation. More specific cardiac imaging studies may provide additional insight into this observation and the influence of dietary sodium in cardiac health.