NEW YORK (Reuters Health) – About 1 in 7 patients 60 years of age or older with heart failure undergoing intensive medical therapy have hyperkalemia, and one risk factor is spironolactone dosage, according to findings reported in the American Journal of Cardiology online“Careful surveillance of serum potassium and cautious use of spironolactone in patients at risk may help to decrease the incidence of potentially hazardous complications caused by hyperkalemia,” the authors advise.Dr. Stefano Muzzarelli, at University Hospital Basel, Switzerland, and colleagues say the incidence of hyperkalemia and associated risk factors has been studied in younger patients with heart failure, but less so in older subjects who make up the bulk of the heart failure population.They therefore examined data from the TIME-CHF study, which included 566 patients at least 60 years of age who were hospitalized with heart failure in the previous year and who had an N-terminal brain natriuretic peptide level >2 times the upper limit of normal. The median age was >75 years, and more than half had chronic renal failure while more than a third had diabetes, the authors note. The trial compared standard therapy with intensified NT-BNP-guided therapy over an 18-month period. During the study, 76 (13.4%) patients had hyperkalemia, defined as a potassium level of 5.5 mmol/L or higher, the researchers found. On multivariate analysis, hyperkalemia was more frequent in patients with a history of gout (odds ratio 2.56), more advanced heart failure symptoms, higher serum creatinine (OR 1.11 per 10 micromol/L) and potassium (OR 2.92 per mmol/L) levels at baseline, and higher dose spironolactone (OR 1.20 per 12.5 mg).The dose of other renin–angiotensin–aldosterone inhibitors or beta-blockers was not linked to hyperkalemia, the report indicates.The risk of hyperkalemia also increased with higher maximal changes in the dose of spironolactone. Compared to no dose change, an increase of 12.5 mg conferred an odds ratio 1.45; with 25 mg, the OR was 2.52; and with dose increases above 25 mg the OR was 6.91.The rate of hyperkalemia jumped in the first month of the study when treatment intensified, underscoring the importance of monitoring, Dr. Muzzarelli and colleagues comment.Despite certain limitations, they conclude, “Our study indicates caution concerning the use of aldosterone antagonists when used too liberally and with insufficient monitoring.” Reference:Comparison of ultrasound and X-ray in determining the position of umbilical venous cathetersAm J Cardiol 2011.