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

The optimal approach towards managing serum potassium and hemodialysate potassium concentrations is uncertain. To study this, adults receiving hemodialysis for three months or more with hyperkalemia (pre-dialysis serum potassium (sK⁺) 5.1-6.5 mEq/l) had cardiac monitors implanted and were randomized to either eight weeks of 2.0 potassium/2.5 calcium mEq/l dialysate without sodium zirconium cyclosilicate (SZC) (2.0 potassium/noSZC) or 3.0 potassium/2.5 calcium mEq/l dialysate combined with SZC (3.0 potassium/SZC) on non-dialysis days to maintain pre-dialysis sK⁺ 4.0-5.5 mEq/l, followed by treatment crossover for another eight weeks. The primary outcome was the rate of adjudicated atrial fibrillation (AF) episodes of 2 minutes or more 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 mEq/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 potassium 3.0 mEq/l and SZC on non-hemodialysis days reduced the rates of AF, other clinically significant arrhythmias, and post-dialysis hypokalemia compared with potassium 2.0/noSZC.