Residual Kidney Function and Response of Left Ventricular Mass to Intensive Hemodialysis: The Frequent Hemodialysis Network Trials.

Frequent (6 times/week) hemodialysis (HD) has been shown to reduce left ventricular mass (LVM) more than conventional (3 times/week) HD in patients with ESKD. Previous work suggested that the LVM benefits of frequent HD might be attenuated in the presence of residual kidney function (RKF). We hypothesized that patients without RKF would have greater LVM reduction with frequent HD compared to patients with RKF. We analyzed data from the Frequent Hemodialysis Network (FHN) Daily (in-center) and Nocturnal (home-based) Trials, which randomized patients with ESKD to either frequent or conventional HD over 12 months. RKF was evaluated through timed 24h urine collections, with anuria defined as urine output <100 mL/day. LVM was assessed via magnetic resonance imaging at baseline and 12 months. Combined trial data were analyzed using log-transformed LVM to evaluate the impact of RKF on LVM change. Among 332 patients from both FHN trials (170 frequent, 162 conventional HD), 189 (57%) were anuric at baseline. Baseline LVM did not differ between anuric and non-anuric patients (log LVM: 4.90±0.32 vs 4.85±0.40; p=0.18). At 12 months, both anuric and non-anuric patients experienced similar LVM reductions with frequent HD (mean change in log LVM: -0.11±0.23 vs -0.08±0.23; p=0.44). No association was found between baseline urine volume and LVM response (rho= -0.002, p=0.98 for frequent; rho=0.003, p=0.97 for conventional HD). Changes in urine volume over 12 months did not correlate with LVM changes. In an exploratory analysis, LVM reduction correlated with urine volume decline in men (rho=0.23; p<0.01) but not in women (rho= -0.19; p= 0.10; pinteraction = 0.003). Both anuric and non-anuric patients experienced similar LVM reductions with frequent HD, and no association between urine output and LVM response was observed in the FHN trials. These data suggest that the response of LVM to frequent HD is independent of baseline residual kidney function.