NEW YORK (Reuters Health) - The mineralocorticoid receptor blocker eplerenone has advantages over spironolactone in the treatment of chronic heart failure (CHF), a Japanese team reports. In particular, eplerenone does not increase hemoglobin A1c levels, suggesting it may be useful in heart failure patients with diabetes.

The authors note in the November issue of the American Heart Journal that HbA1c levels have recently been tied to increased mortality in both diabetic and nondiabetic CHF patients, “suggesting the important role of insulin resistance in CHF.” Also, they point out, cortisol is a risk factor for cardiovascular complications and it impairs insulin secretion.

Dr. Takayoshi Tsutamoto, and colleagues at Shiga University of Medical Science, Tsukinowa, Seta, Otsu, Japan conducted a randomized trial to compare the effect of eplerenone and spironolactone on HbA1c and cortisol, as well as other parameters, in 107 patients with mild CHF who were already being treated with standard therapy.

Thirty-four patients were assigned to spironolactone 25 mg/d and the others received eplerenone 50 mg/d.

After 4 months of treatment, plasma B-type natriuretic peptide (BNP) levels decreased significantly by 29.9 pg/mL in the spironolactone group and 20.7 pg/mL in the eplerenone group -- a nonsignificant difference. The increase in aldosterone was also not significantly different between the two groups (37.4 pg/mL vs 46.3 pg/mL).

However, in the spironolactone group, plasma adiponectin levels decreased significantly from 12.6 to 11.2 mcg/mL, HbA1c increased significantly from 5.61% to 5.8%, and cortisol levels rose significantly from 11.3 to 14.7 mcg/dL. These parameters were essentially unchanged in the group receiving eplerenone.

“These findings indicated that a selective MR blocker eplerenone was superior to spironolactone due to differences in metabolic effects especially those on HbA1c in CHF patients,” Dr. Tsutamoto and colleagues conclude. “Compared with spironolactone, eplerenone may be more useful for treatment of CHF patients from the perspective of insulin resistance and cortisol levels, which were related to poor prognosis.”

Am Heart J 2010;160:915-921.