Aldosterone receptor antagonists spironolactone and eplerenone for congestive heart failure
In a randomized trial 1 patients (n=1,663) with severe congestive heart failure, an ejection fraction 35% or less and receiving ACE inhibitors and loop diuretics received either spironolactone 25mg/day or placebo. Potassium-sparing diuretics were not permitted. Patients were excluded from the study if they had primary operable valvular heart disease (other than mitral or tricuspid regurgitation with clinical symptoms due to left ventricular systolic heart failure), congenital heart disease, unstable angina, primary hepatic failure, active cancer, or any life-threatening disease (other than heart failure). Patients who had undergone heart transplantation or were awaiting the procedure were also ineligible. Other criteria for exclusion were a serum creatinine concentration of more than 2.5 mg per deciliter (221 µmol per liter) and a serum potassium concentration of more than 5.0 mmol per liter. The relative risk for total mortality at two years was 0.70 (95% CI 0.60 to 0.82) and the relative risk for hospitalisation was 0.65 (95% CI 0.54 to 0.77) in favour of spironolactone. Also symptoms of heart failure decreased with spironolactone therapy. Severe hyperkalemia was rare.
According to a Canadian population-based time-series analysis 2 the publication of RALES was associated with increases in the rate of prescriptions for spironolactone (from 34 per 1000 patients in 1994 to 149 per 1000 patients by late 2001; P<0.001), in the rate of hospitalization for hyperkalemia (from 2.4 per 1000 patients in 1994 to 11.0 per 1000 patients in 2001; P<0.001), and the associated mortality (from 0.3 per 1000 to 2 per 1000 patients; P<0.001).
In a randomized trial 3 patients (n=6,632) with acute myocardial infarction complicated by left ventricular dysfunction (LVEF ≤ 40%) and heart failure or diabetes received either eplerenone (25 mg - 50 mg per day) or placebo in addition to optimal medical therapy. Criteria for exclusion were the use of potassium-sparing diuretics, a serum creatinine concentration of more than 2.5 mg per deciliter (220 µmol per liter), and a serum potassium concentration of more than 5.0 mmol per liter before randomization. The relative risk for total mortality (mean follow-up of 16 months) was 0.85 (95% CI 0.75 to 0.96) and for cardiovascular disease mortality 0.83 (95% CI 0.72 to 0.94). Also the rate of death from cardiovascular causes or hospitalization for cardiovascular events was reduced by eplerenone (RR 0.87, 95% CI 0.79 to 0.95). The rate of serious hyperkalemia was 5.5 percent in the eplerenone group and 3.9 percent in the placebo group (P=0.002), whereas the rate of hypokalemia was 8.4 percent in the eplerenone group and 13.1 percent in the placebo group (P<0.001).
In a randomized trial 4 (EMPHASIS-HF) 2737 patients with NYHA class II heart failure, an ejection fraction of no more than 35% (mean 26%), and already using diuretics, ACE inhibitors/angiotensin receptor blockers and beta-blockers, received either eplerenone (up to 50 mg/d) or placebo. The trial was stopped early after a median follow-up of 21 months. The primary composite outcome (cardiovascular death or hospitalization for heart failure) occurred in 18.3% of patients in the eplerenone group and 25.9% in the placebo group (HR 0.63, 95% CI 0.54 to 0.74). A total of 12.5% of patients receiving eplerenone and 15.5% of those receiving placebo died (HR 0.76, 95% CI 0.62 to 0.93). A serum potassium level exceeding 5.5 mmol/ll occurred in 11.8% of patients in the eplerenone group and 7.2% of those in the placebo group.
A systematic review and meta-analysis 5 included 8 studies with a total of 3,929 subjects with congestive heart failure with NYHA classes I to II. Aldosterone antagonists reduced all cause mortality (RR 0.79, 95% CI 0.66, 0.95) and re-hospitalization for cardiac causes (RR 0.62, 95% CI 0.52, 0.74) compared to control. A stratified analysis showed a statistical superiority in the benefits of spironolactone over eplerenone in reducing left ventricular end-diastolic volume and left ventricular end-systolic volume. Aldosterone antagonists reduced B-type natriuretic peptide concentrations, P < 0.00001), increased serum creatinine, and occurrence of hyperkalaemia (RR 1.78, 95% CI 1.43, 2.23).
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