Purpose: We conducted a double-blind, placebo-controlled trial to determine whether the administration of acetylsalicylic acid has adverse effects on renal function in patients with moderate chronic congestive heart failure with and without stimulation of the renin system.
Patients and methods: Forty patients were randomly assigned to one of the following four groups: Group 1, low sodium diet and placebo; Group 2, low sodium diet and acetylsalicylic acid; Group 3, normal sodium diet and placebo; or Group 4, normal sodium diet and acetylsalicylic acid. Patients were studied over 8 days. After Day 5, patients in Groups 2 and 4 received acetylsalicylic acid (500 mg three times a day). The low sodium diet consisted of 13.6 mmol of sodium per day and the normal sodium diet consisted of 136 mmol of sodium per day.
Results: The low sodium diet resulted in a highly significant increase in the plasma renin (2p = 0.0001), aldosterone (2p = 0.0006), and urinary prostaglandin E2 (2p = 0.01) concentrations and the renal potassium excretion (2p = 0.0009), whereas renal sodium excretion was significantly reduced (2p = 0.0001). Severe sodium depletion led to a reduction of the glomerular filtration rate (2p = 0.007), which was independent from cyclooxygenase inhibition. In patients on the low sodium diet, acetylsalicylic acid reduced the elevated urinary prostaglandin E2 levels to normal values without changing the renal sodium excretion rate. In patients with a normal sodium intake, acetylsalicylic acid significantly reduced the renal sodium excretion rate by 29% (2p = 0.04).
Conclusion: We conclude that severe sodium depletion has adverse effects on kidney function in patients with heart failure due to a reduction in the glomerular filtration rate. Administration of acetylsalicylic acid in doses that reduce the synthesis of renal prostaglandin E2 significantly reduces renal sodium excretion.