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

Background: Increasing 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). Methods: We 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). Results: We 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/m(2) vs. 108 [91-122] g/m(2)) 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). Conclusion: In 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.