Abstract
BACKGROUND: Determination of left ventricular hypertrophy (LVH) via electrocardiogram (ECG) is a known independent risk factor for cardiovascular morbidity and mortality in hypertension (HTN). Dietary sodium and HTN are both associated with unfavorable alterations in left ventricular mass, however, to what extent their interplay affects ECG screening for LVH is unclear. METHODS: The effects of controlled dietary sodium manipulation on ECG determinants of LVH in hypertensive subjects were evaluated using well-established voltage criteria for LVH. ECGs from 80 hypertensive subjects were evaluated following random sequence assignment to 7 days of high sodium (HS) intake (200 mEq/24 h), and then 7 days of low sodium (LS) intake (10 mEq/24 h). RESULTS: Sodium restriction over 7 days resulted in significant decreases in overall, and LVH-specific, ECG voltages. Most subjects exhibited decrements in overall ECG voltage with sodium restriction (72%); however, a smaller subset displayed higher voltages when on LS intake (28%). The prevalence of ECG-determined LVH was significantly lowered with LS diet (HS diet 22/80 (28%) vs. LS diet 8/80 (10%), P < 0.05). Subjects exhibiting reversal of LVH status with sodium restriction were younger, demonstrated salt sensitivity of blood pressure, and lower LVH-specific ECG voltage. CONCLUSIONS: Short-term dietary sodium fluctuations can significantly alter overall ECG voltage and the prevalence of ECG-determined LVH in hypertensive individuals. Inclusion of dietary sodium assessment when screening hypertensive subjects for LVH by ECG may improve the consistency of cardiac risk assessment.