Changes in extracellular water and left ventricular mass in peritoneal dialysis patients.

backgroundIncreasing number of peritoneal dialysis (PD) patients are reported to have increased left ventricular hypertrophy (LVH), a major risk factor for cardiovascular mortality. We wished to determine which factors were most associated with changes in left ventricular mass index (LVMI).

methodsWe reviewed patient and treatment factors in prevalent PD patients with repeat echocardiograms 18 to 24 months apart, with corresponding bioimpedance measurements of extracellular water (ECW) and serum N-terminal pro-brain natriuretic peptide (NT-proBNP).

resultsWe studied 60 patients (34 males, 35 with diabetes) who were treated with PD for a median of 14 months (2.5-26.3 months). All but one had LVH; on repeat echocardiography, there was no overall change in LVMI (106 [84-127] g/m2 vs. 108 [91-122] g/m2) despite a loss of residual renal function. Left ventricular mass increased in 34 (56.7%), and the percent change in LVMI was associated with percent change in NT-proBNP (r = 0.51, p = 0.017) and ECW/height (r = 0.32, p = 0.029), but not with ECW/total body water or changes in systolic or mean arterial pressure, urine output, 24-hour PD ultrafiltration, or net sodium balance. Only ECW/height remained independently associated with the percent change in LVMI in a multivariable model (odds ratio, 1.25; 95% confidence interval, 1.08-1.36; p = 0.007).

conclusionIn this observational longitudinal report, a reduction in ECW/height was associated with regression of LVMI, whereas an increased ECW/height was associated with increased LVMI. As there was no corresponding association with systolic or mean arterial pressure, then volume expansion would appear to be a more significant factor in determining LVH than blood pressure.