Safety of concomitant potassium-sparing diuretics in angiotensin-converting enzyme inhibitor therapy in severe congestive heart failure. Xamoterol in Severe Heart Failure Study Group.

The safety of concomitant use of angiotensin-converting enzyme (ACE) inhibitors and potassium-sparing diuretics (PSD) in severe heart failure remains a controversial issue. The database of the recently reported double-blind international trial, "Xamoterol in Severe Heart Failure," was investigated to elucidate this question. Of 516 patients with New York Heart Association (NYHA) class III-IV, despite diuretics and ACE inhibitor therapy, 352 were randomized to xamoterol, a beta 1 partial agonist, and 164 were randomized to placebo. During the 13-week study, 28% of all patients (xamoterol, 104; placebo, 42) received potassium-sparing diuretics. All groups were comparable in hemodynamics and dose of other diuretics. At study end, patients with or without PSD showed no significant differences in serum K+ or creatinine, independent of xamoterol or placebo therapy. Mortality rate was consistently lower: 4.6% in patients with PSD and 8.5% in patients without PSD, although statistical significance was not reached. As compared with baseline, K+ values of 6 patients with and 17 patients without PSD had increased by > 5.0 mM at study end (p = NS); 1 patient with and 11 patients without PSD had a creatinine level > 180 microM (p = NS). For 3 patients receiving PSD, and 2 patients not receiving PSD because of renal impairment, study was discontinued because of hyperpotassemia. No significant differences were noted in long and short action or different dosages of ACE inhibitors. PSD may be administered concomitantly with ACE inhibitors, but serum K+ should be monitored as with other diuretics.