Research Activities, August 2013
Aldosterone antagonists reduce readmission for heart failure, but boost risk of readmission for excess potassium
A new study shows that older patients with heart failure and reduced ejection fraction (weak pumping power of the heart), who start taking aldosterone antagonist (AA) drugs when discharged from the hospital, do not show the decreased mortality or hospital readmissions for cardiovascular problems observed in randomized clinical trials. These patients did exhibit reduced readmission for heart failure, but also showed a significant increase in their risk of readmission for high blood potassium (hyperkalemia).
The AA drugs (spironolactone and eplerenone) are diuretic agents that cause reduction in sodium—but not potassium—levels in the blood via the kidneys. Although, in landmark randomized clinical trials, the AAs were found to reduce mortality among patients with heart failure and reduced ejection fraction by 24 to 30 percent, and hospital readmissions by 40 percent, no good study had been done of the drugs’ effects in patients seen as part of regular clinical practice.
In this study, the researchers followed 5,887 patients enrolled in a clinical registry for heart failure patients; 1,070 (18.2 percent) began AA therapy after hospital discharge. When the AA treated and untreated groups were compared, cumulative incidence rates for mortality (49.9 percent vs. 51.2 percent) and cardiovascular readmission (63.8 percent vs. 63.9 percent) were not significantly different. However, the cumulative rates of heart failure readmission at 3 years (38.7 percent vs. 44.9 percent) and hyperkalemia readmissions within 30 days (2.9 percent vs. 1.2 percent) were significantly different.
The findings were based on data from the heart failure clinical registry, linked to Medicare claims, for 2005–2010, for those age 65 years or older. The study was funded by AHRQ (Contract No. 290-05-0032 and grant HS21092).
More details are in "Associations between aldosterone antagonist therapy and risks of mortality and readmission among patients with heart failure and reduced ejection fraction," by Adrian F. Hernandez, M.D., M.H.S., Xiaojuan Mi, Ph.D., Bradley G. Hammill, M.S., and others in the November 28, 2012, Journal of the American Medical Association 308(20), pp. 2097-2107.