Effects of Spironolactone on Arrhythmias in Hemodialysis Patients: Secondary Results of the SPin-D Randomized Controlled Trial.

Background Patients receiving maintenance hemodialysis (HD) have a high incidence of cardiovascular events, including arrhythmia and sudden death. Spironolactone reduces the risk of cardiovascular events and sudden death in patients with heart failure, but the effects of spironolactone on arrhythmic events in patients treated with maintenance HD are unclear. Methods The Safety and Cardiovascular Efficacy of Spironolactone in Dialysis-Dependent ESRD (SPin-D) trial, was a 36-week randomized, placebo-controlled, double-blind trial comparing 3 different doses of spironolactone with placebo in maintenance HD patients. We performed a post-hoc analysis in a subset (n=57) who underwent extended electrocardiographic monitoring using a wearable device at baseline and follow-up. Generalized estimating equations models were fit to determine the associations of spironolactone (individual doses and combined) versus placebo on the incidence rate of predefined categories of arrhythmic events. Results The average age of participants was 55 ±12 years; 61% were male; and 77% were Black. The overall proportion of patients with at least one arrhythmia event was 43% (15/35) at baseline and 81% (43/53) at the end of follow-up. At the end of follow-up, the rate of bradycardic events or conduction blocks was higher in the combined spironolactone group, compared with placebo, (82.4 versus 38.7 events/100 patient days; P<0.001). Similar findings were noted in adjusted models, but did not meet statistical significance (adjusted rate ratio of 2.04; 95%CI 0.83 - 5.05). Conclusions In a 36-week trial of patients receiving maintenance hemodialysis, a higher frequency of bradycardia and conduction blocks was observed among those treated with spironolactone treatment compared with placebo. Larger studies are required to investigate the longer-term effects of spironolactone on cardiac conduction in patients receiving hemodialysis.