Effects of dialysate potassium concentration of 3.0 mmol/l with sodium zirconium cyclosilicate on dialysis-free days versus dialysate potassium concentration of 2.0 mmol/l alone on rates of cardiac arrhythmias in hemodialysis patients with hyperkalem

The optimal approach towards managing serum potassium (sK⁺) and hemodialysate potassium concentrations is uncertain. To study this, adults receiving hemodialysis for three months or more with hyperkalemia (pre-dialysis sK⁺ 5.1-6.5 mmol/l) had cardiac monitors implanted and were randomized to either eight weeks of 2.0 mmol/l potassium/1.25 mmol/l calcium dialysate without sodium zirconium cyclosilicate (SZC) (2.0 potassium/noSZC) or 3.0 mmol/l potassium/1.25 mmol/l calcium dialysate combined with SZC (3.0 potassium/SZC) on non-dialysis days to maintain pre-dialysis sK⁺ 4.0-5.5 mmol/l, followed by treatment crossover for another eight weeks. The primary outcome was the rate of adjudicated atrial fibrillation (AF) episodes of at least 2 minutes duration. Secondary outcomes included clinically significant arrhythmias (bradycardia, ventricular tachycardia, and/or asystole) and the proportion of sK⁺ measurements within an optimal window of 4.0-5.5 mmol/l. Among 88 participants (mean age: 57.1 years; 51% male; mean pre-dialysis sK⁺: 5.5 mmol/l) with 25.5 person-years of follow-up, 296 AF episodes were detected in nine patients. The unadjusted AF rate was lower with 3.0 potassium/SZC versus 2.0 potassium/noSZC; 9.7 vs. 13.4/person-year (modeled rate ratio 0.52; 95% confidence interval 0.41-0.65). Clinically significant arrhythmias were reduced with 3.0 potassium/SZC vs. 2.0 potassium/noSZC (6.8 vs. 10.2/person-year modeled rate ratio 0.47; 0.38; 0.58). Fewer sK⁺ measurements outside the optimal window occurred with 3.0 potassium/SZC (modeled odds ratio: 0.27; 0.12-0.35). Hypokalemia was less frequent (33 vs. 58 patients) with 3.0 potassium/SZC compared with 2.0 potassium/noSZC. Thus, in patients with hyperkalemia on maintenance hemodialysis, a combination of hemodialysate potassium 3.0 mmol/l and SZC on non-hemodialysis days reduced the rates of AF, other clinically significant arrhythmias, and post-dialysis hypokalemia compared with hemodialysate potassium 2.0/noSZC.