Adverse cardiac effects of salt with fludrocortisone in hypertension

The effect of salt on blood pressure (BP) is controversial. A more importan t question is whether salt can produce cardiac target-organ damage, irrespe ctive of its effect on BP. We assessed the effect of salt with fludrocortis one on QT dispersion and echocardiographic left ventricular diastolic funct ion in a prospective interventional study involving 29 hypertensive subject s with a raised aldosterone/renin ratio who were hospitalized for investiga tion of possible primary aldosteronism. Each subject over 4 days was given a total of 28.8 g (480 mmol) of sodium chloride and 1.5 mg of fludrocortiso ne with potassium supplementation. Baseline and posttreatment 12-lead ECGs and echocardiograms were obtained. There were no significant changes in bod y weight, pulse rate, or BP after treatment with salt and fludrocortisone. Plasma sodium was significantly increased from 141.4 (SD 2.1) to 142.6 (SD 2.4) mmol/L (P = 0.001), QT and QTc dispersion both significantly increased : +19.6 (SD 16.5) ms (95% CI, 13.4 to 25.9) (P < 0.001) and +19.8 (SD 20.9) ms (95% CI, 11.8 to 27.7) (P < 0.001), respectively. There were no signifi cant changes in (n = 15) left ventricular dimensions or systolic function, but all diastolic filling indexes, including the preload-independent index, flow propagation velocity (55.49 [SD 10.91] to 48.96 [SD 11.40] cm/s, P = 0.018) worsened, suggesting significant deterioration of left ventricular d iastolic function with salt and fludrocortisone. In conclusion, a combinati on of salt with fludrocortisone increased QT dispersion and impaired left v entricular diastolic relaxation in hypertensive patients with high aldoster one/renin ratios. This raises the possibility that salt may have BP-indepen dent adverse cardiac effects in susceptible hypertensive subjects.