Use of aldosterone antagonists is associated with an increased risk of hyperkalemia and acute renal failure among older patients with reduced ejection fraction after acute myocardial infarction (MI), according to a new study.

Tracy Y. Wang, MD, MS, of Duke University Medical Center in Durham, N.C., and colleagues studied 12,081 MI patients aged 65 years and older with an ejection fraction (EF) of 40% or less. Of these, 1,310 (11%) were prescribed aldosterone antagonists—predominantly spironolactone—at discharge.

At 2-year follow-up, aldosterone antagonist use was not associated with lower mortality, except in patients with in-hospital signs and symptoms of heart failure (HF), who had a significant 16% decreased risk of death.

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Hyperkalemia occurred significantly more frequently at 30 days among patients prescribed aldosterone antagonists at discharge than those who were not (2.3% vs. 1.5%), the researchers reported online in the Journal of the American Heart Association. In adjusted analyses, patients prescribed aldosterone antagonists had a 2-fold increased risk of hyperkalemia at 30 days. Significantly more patients prescribed aldosterone antagonists experienced acute renal failure at 2 years than those not prescribed the drugs (6.7% vs. 4.8%). In adjusted analyses, patients prescribed the drugs had a significant 39% increased risk of acute renal failure.

The authors said their findings suggest a stronger recommendation for aldosterone antagonist use among older MI patients with low EF and in-hospital HF.

“This study also underscores the importance of close post-discharge monitoring of renal function and electrolytes for older MI patients who are prescribed aldosterone antagonist therapy,” they wrote.