The safety of spironolactone treatment in patients with heart failure

Introduction: Spironolactone is increasingly being used in the treatment of heart failure. However, it has been associated with cases of hyperkalaemia. The common use of angiotensin-converting enzyme (ACE) inhibitors and angiotensin-2 receptor (AT2) antagonists in heart failure increases the risk of hyperkalaemia. Objective: To identify the risk of spironolactone withdrawal, hyperkalaemia and severe hyperkalaemia in patients prescribed spironolactone together with either an ACE inhibitor or an AT2 antagonist. Methods: Retrospective identification and analysis of patients co-prescribed an ACE inhibitor or an AT2 antagonist with spironolactone. Patients' records were linked to their biochemical results and the doses of spironolactone, ACE inhibitor and AT2 antagonists received by them. Results: We found that a higher proportion of patients in our cohort stopped taking spironolactone compared with the Randomised Aldactone Evaluation Study and a higher proportion developed hyperkalaemia, a predicted adverse effect of spironolactone combination with an ACE inhibitor or an AT2 antagonist. Patients with diabetes mellitus and those with a haematocrit below 0.36, were more likely to develop hyperkalaemia than those without these traits. Conclusions: Spironolactone is a common cause of hyperkalaemia when used in combination with either an ACE inhibitor or an AT2 antagonist. This reinforces the need for care when extrapolating the results of clinical trials to daily clinical practice.