Abstract: Objective The aim of this study was to investigate the impact of potassium concentration in dialysate on maximum P wave duration (Pmax) and P wave dispersion (Pd). Methods A total of 117 maintenance hemodialysisi (MHD) patients with sinus rhythm and treated in the period from Nov. 2014 to Jan. 2015
were enrolled in this self-controlled study. Dialysate containing 2.5 mmol/L K+ (DK2.5) was used in the first week, and dialysate containing 3.0 mmol/L K+ (DK3.0) was used in the next week, followed by DK2.5 thereafter. Ultrafiltration volume in a dialysis session, serum creatinine, BUN, electrolytes, blood pressure, heart rate, and twelve-lead electrocardiogram were measured at the beginning of study, after DK2.5 for a week, and after DK3.0 for a week. Results In the 117 MHD patients (58 males, average age 56.7 years, and median MHD duration 77.3 months), ultrafiltration volume, blood pressure and heart rate were statistically unchanged between dialysis sessions. Biochemistry parameters before dialysis were similar after DK2.5 period and after DK3.0 period. Serum potassium increased (4.0 ± 0.4mmol/L vs. 3.7 ± 0.3mmol/L, t=10.159, P＜0.001) after DK3.0 for a week. Pmax and Pd were prolonged after dialysis. Pmax and Pd after DK3.0 period were shorter than those after DK2.5 period (for Pmax, 115.8±10.7 ms vs. 121.1±11.6 ms, t=-6.215, P＜0.001; for Pd, 40.4± 9.7 ms vs. 46.2±10.3 ms, t=-5.989, P＜0.001). Changes of serum potassium (ΔK+) had no linear relationship with the changes of Pmax (ΔPmax) before and after a dialysis session during the DK2.5 and DK3.0 periods, nor with the changes of Pd (ΔPd). Conclusion Higher potassium concentration (DK3.0) in dialysate can alleviate
the prolonged Pmax and Pd after hemodialysis. However, whether long-term DK3.0 can reduce the incidence of atrial fibrillation in MHD patients remains to be studied.

Key words: maximum P wave duration, P wave dispersion, dialysate potassium concentration, hemodialysis, atiral fibrillation