Abstract
OBJECTIVE: To determine whether chronic phosphodiesterase-V (PDEV) inhibition with tadalafil will improve urinary sodium excretion, glomerular filtration rate (GFR), plasma cyclic guanosine 3', 5'-monophosphate (cGMP), and urinary cGMP excretion in response to volume expansion (VE) in patients with preclinical diastolic dysfunction (PDD) or stage B heart failure. BACKGROUND: PDD is defined as abnormal diastolic function with normal systolic function, without clinical heart failure. PDD is predictive of development of heart failure and all-cause mortality. Impaired renal function and attenuated cGMP response to VE are hallmarks of PDD. METHODS: A double-blind, placebo-controlled, proof-of-concept study was conducted to compare 12 weeks of tadalafil 20 mg daily (n = 14) vs placebo (n = 7). Subjects underwent 2 study visits 12 weeks apart. Renal, neurohormonal and echocardiographic assessments were performed before and after intravascular VE (normal saline 0.25 mL/kg/min for 1 hour). RESULTS: Baseline characteristics were similar. There was no increase in GFR, plasma cGMP or urinary cGMP excretion in response to VE in either group at visit 1. At visit 2, tadalafil did not result in significant change in GFR but increased plasma cGMP and urinary cGMP excretion at baseline. In response to VE, tadalafil resulted in increased urine flow, urinary sodium excretion, GFR (7.00 [-1.0, 26.3] vs -9.00 [-24.5, 2.0] mL/min/1.73m2; P = 0.02) and plasma cGMP (0.50 [-0.1, 0.7] vs -0.25 [-0.6, -0.1] pmol/mL; P = 0.02). It did not improve urinary cGMP excretion after VE. CONCLUSION: In PDD, chronic PDEV inhibition with tadalafil improved renal response to VE through increased urine flow, urinary sodium excretion, GFR, and plasma cGMP. Further studies are required to determine whether this enhanced renal response can mitigate progression to clinical heart failure.