ABNORMALITIES OF SODIUM HANDLING AND OF CARDIOVASCULAR ADAPTATIONS DURING HIGH-SALT DIET IN PATIENTS WITH MILD HEART-FAILURE

Background. Sodium retention and hormonal activation are fundamental h allmarks in congestive heart failure. The present study was designed t o assess the ability of patients with asymptomatic to mildly symptomat ic heart failure and no signs or symptoms of congestion to excrete ing ested sodium and to identify possible early abnormalities of hormonal and hemodynamic mechanisms related to sodium handling. Methods and Res ults. The effects of a high salt diet (250 mEq/day for 6 days) on hemo dynamics, salt-regulating hormones, and renal excretory response were investigated in a balanced study in 12 untreated patients with idiopat hic or ischemic dilated cardiomyopathy and mild heart failure (NYHA cl ass I-II, ejection fraction < 50%) (HF) and in 12 normal subjects, who had been previously maintained a 100 mEq/day NaCl diet. In normal sub jects, high salt diet was associated with significant increases of ech ocardiographically measured left ventricular end-diastolic volume, eje ction fraction, and stroke volume (all P<.001) and with a reduction of total peripheral resistance (P<.001). In addition, plasma atrial natr iuretic factor (ANF) levels increased (P<.05), and plasma renin activi ty and aldosterone concentrations fell (both P<.001) in normals in res ponse to salt excess. In HF patients, both left ventricular end-diasto lic and end-systolic volumes increased in response to high salt diet, whereas ejection fraction and stroke volume failed to increase, and to tal peripheral resistance did not change during high salt diet. In add ition, plasma ANF levels did not rise in HF in response to salt loadin g, whereas plasma renin activity and aldosterone concentrations were a s much suppressed as in normals. Although urinary sodium excretions we re not significantly different in the two groups, there was a small bu t systematic reduction of daily sodium excretion in HF, which resulted in a significantly higher cumulative sodium balance in HF than in nor mals during the high salt diet period (P<.001). Conclusions. These res ults show a reduced ability to excrete a sodium load and early abnorma lities of cardiac and hemodynamic adaptations to salt excess in patien ts with mild heart failure and no signs or symptoms of congestion.