EFFECT OF A NEW MODEL OF HEMODIALYSIS POTASSIUM REMOVAL ON THE CONTROL OF VENTRICULAR ARRHYTHMIAS

The primary aim of this multicenter, prospective, randomized cross-ove r study was to clarify whether a new model of hemodialysis (HD) potass ium (K) removal using a decreasing intra-HD dialysate K concentration and a constant plasma-dialysate K gradient (treatment B) is capable of reducing the arrhythmogenic effect of standard HD, which has a consta nt dialysate K concentration and decreasing plasma-dialysate K gradien t (treatment A). The secondary aim was to verify whether this new mode l is clinically safe. In treatment B, the initial dialysate K concentr ation had to be 1.5 mEq/liter less than the plasma K concentration, an d exponentially decrease to 2.5 mEq/liter at the end of HD. Forty-two chronic HD patients with an increase in premature ventricular complexe s (PVC) during dialysis were enrolled from 18 participating centers, a nd randomly assigned to either sequence 1 (ABA) or sequence 2 (BAB). A pool of 333 of 378 expected ECG Holter recordings were checked for si gnal quality; 269 (71%) from 36 patients (86%) had a satisfactory sign al quality and 108 were selected for analysis (1 per patient per perio d). There was a difference in the natural logarithm of the increase in PVC/hr and PVC couplets/hr during HD between treatments A and B (1.70 +/- 1.59 vs. 1.09 +/- 1.76 and 0.94 +/- 0.86 vs. 0.64 +/- 1.01, a red uction of 36% and 32%, P = 0.011 and 0.047, respectively) without any carry over effect (P = 0.61 and 0.24, respectively). The fact that thi s decrease of one third is due to a lower plasma-dialysate K gradient is supported by the observation that it was more evident during the fi rst than the last two hours of HD (a reduction in the natural logarith m of the increase in PVC/hr and PVC couplets/hr of 60% and 60%, P 0.00 2 and 0.009, vs. 26% and 17%, P = 0.098 and 0.332, respectively): the initial plasma-dialysate K gradient was 2.3 times lower during treatme nt B than during treatment A, without adversely affecting pre-HD plasm a K levels. These results could have a considerably clinical impact no t only because of the possibility of physiologically decreasing the ar rhythmogenic effect of HD, but also because this effect can be conside red a ''marker'' of the electrophysiological derangement induced by th e administration of standard HD three times a week for years (''electr ic disequilibrium syndrome'').