Impact of dietary sodium intake on left ventricular diastolic filling in early essential hypertension

Aims Dietary sodium intake modulates left ventricular hypertrophyin established essential hypertension independent of blood pressurelevel. We conducted this study to elucidate the relationshipbetween sodium intake and left ventricular structural or functionalchanges in early essential hypertension. Methods Forty-four young male patients (age 25·9±2·6years) with mild essential hypertension that had never beentreated and 45 normotensive male control subjects of similarage were examined. Dietary sodium intake was measured from 24hurinary sodium excretion, blood pressure from 24h ambulatorymonitoring (SpaceLabs 90207), left ventricular structure from2-D guided M-mode echocardiography, and diastolic filling ofthe left ventricle (as the main compound of diastolic functionin a young population) by pulse-wave Doppler sonography. Results In hypertensive patients, daily sodium excretion correlatedwith the ratio of late (A) to early (E) maximum velocity (VmaxA/E; r=+0·27,P=0·07), velocity time integrals(A/E; r=+0·54,P<0·001) as well as atrial contribution,as a percent of left ventricular filling (VH ATCO; r=+0·52,P<0·001)independent of heart rate, whereas the opposite correlationswere observed in normotensives (allP<0·001). Stepwisemultiple regression analysis confirmed these results. Sodiumexcretion emerged as the strongest independent determinant ofimpaired diastolic filling in hypertensive patients (velocitytime integrals A/E: R²=0·49, ß=+0·57,P=0·0001;VH ATCO: R²=0·48, ß=+0·56,P<0·0001;Vmax A/E: ns). In normotensive subjects, sodium excretion wasa similar strong, but inverse deter-minant of diastolic filling(velocity time integrals A/E: R²=0·40, ß=–0·43,P=0·0028).Heart rate was a strong determinant of diastolic filling inhypertensive patients (ß=+0·55,P=0·0002)and in normotensive subjects (ß=+0·34,P=0·011).Left ventricular mass and end-diastolic volume index were notrelated to diastolic filling in either group. Conclusion In early essential hypertension, sodium excretion is correlatedwith impaired left ventricular diastolic filling independentof left ventricular mass. The renin-angiotensin-aldosteronesystem might be a mediator of the observed correlation.