Short term efficacy and safety of low dose tolvaptan in patients with acute decompensated heart failure with hyponatremia: a prospective observational pilot study from a single center in South India

BACKGROUND: In acute decompensated heart failure (ADHF), diuretic use, the mainstay therapy for congestion, is associated with electrolyte abnormalities and worsening renal function. Vasopressin mediates fluid retention in heart failure. In contrast to diuretics, the vasopressin antagonist tolvaptan may increase net volume loss in heart failure without adversely affecting electrolytes and renal function. Hyponatremia (serum sodium concentration, <135 mEq/L) is a predictor of death among patients with heart failure. OBJECTIVE: We prospectively observed the short term efficacy and safety of low dose (15 mg) tolvaptan in admitted patients with hyponatremia and ADHF in Indian population. METHODOLOGY: A total of 40 patients with ADHF along with hyponatremia (<125 mEq/L) on standard therapy were treated with 15 mg of tolvaptan at a single oral dose for 7 days. RESULTS: Serum sodium concentrations increased significantly after treatment with tolvaptan from baseline (P < 0.02). There was a significant improvement in symptoms and New York Heart Association (NYHA) class after starting tolvaptan (P ≤ 0.05). Total diuretic dose and mean body weight was reduced non-significantly at 7(th) day from the baseline. Side-effects associated with tolvaptan included increased thirst, dry mouth and increased urination. Few patients had worsening renal function. However, several patients developed hypernatremia. CONCLUSION: In this small observational study, tolvaptan initiation in patients with ADHF with hyponatremia in addition to standard therapy may hold promise in improvement in NYHA class and serum sodium. At the same time, we observed that serious adverse events such as renal function deterioration and hypernatremia developed after tolvaptan treatment, which needs to be addressed in future by randomized study with larger sample size.