Effects of the Aldosterone Antagonist Spironolactone on Ventricular Arrhythmias and Serum Electrolyte Levels in Congestive Heart Failure

The effects of spironolactone 75 mg/day on heart failure and arrhythmia were evaluated in patients with chronic heart failure who had been maintained on a loop diuretic (furosemide) for 4 weeks or more. The effects on heart failure, indicated by improvement in subjective symptoms and clinical signs, were observed. While the frequencies of premature ventricular contraction measured by the two Holier monitorings at the pretreatment period did not differ significantly from each other, each of two Holier monitorings performed after treatment was initiated showed a tendency towards lower frequency compared with the two pretreatment measurements. Serum potassium levels were increased after treatment, but remained within the normal range throughout the treatment period. In the present study, we found that the aldosterone antagonist spironolactone improved the condition of patients with chronic heart failure [i.e. subjective symptoms and clinical signs improved, cardiothoracic ratio and echocardiographic parameters (left ventricular end-diastolic and -systolic dimensions and percentage of fractional shortening) significantly improved (p < 0.05), and New York Heart Association class also improved] treated with a loop diuretic, without inducing an imbalance in serum electrolyte levels. Furthermore, changes after spironolactone treatment in plasma renin activity, plasma aldosterone, plasma angiotensin II and human atrial natriuretic peptide were compared between the total evaluable patients and evaluable subpatients for occurrence of premature ventricular contractions. In the total evaluable patients, levels of the above first three parameters were increased, while human atrial natriuretic peptide decreased significantly. Similar results were obtained in those evaluable for occurrence of premature ventricular contractions. It was concluded that the abovementioned action of spironolactone possibly influenced ventricular arrhythmia associated with heart failure, contributing to an ameliorating tendency in arrhythmia.