Cardiomyopathy in patients with end-stage renal disease on long-term peritoneal dialysis therapy : a prospective, longitudinal observational study

Abstract

Chronic kidney disease is a global health problem. The prevalence of end-stage renal disease (ESRD) has been increasing with a high economic cost. While renal replacement therapy in form of dialysis has substantially improved the morbidity and mortality, the overall mortality in dialysis patients remains substantially higher than in the general population. Of these, cardiovascular disease remains the leading cause of death. While it has been well recognized the structural and functional alterations of the cardiovascular system during the course of ESRD, previous works have been mostly in single-time point, cross-sectional studies focusing on the left ventricular changes in ESRD patients maintained on hemodialysis. There has been a paucity of longitudinal data with comprehensive cardiovascular assessments in ESRD patients receiving maintenance continuous ambulatory peritoneal dialysis (CAPD), which is the most common mode of renal replacement therapy in Hong Kong.

This thesis describes a prospective, long-term, longitudinal observational study from September 2009 to March 2017 involving a total of 192 ESRD patients receiving maintenance peritoneal dialysis to serially evaluate cardiovascular structural and functional alterations in a yearly basis. First we explored the relationship between baseline echocardiographic parameters and exercise capacity, as measured by the peak oxygen consumption (peak VO2), and its determinants in these ESRD patients in a cross-section fashion. Of 192 patients, peak VO2 was reduced to 18.6 ± 5.1 ml/kg/min: 166 patients (86.5%) with decreased exercise capacity and 82 patients (42.7%) with severely decreased exercise capacity. In multivariate analysis, only increasing age and increase in body fluid status as measured using bio-impedance predicted peak VO2.

In the second analysis, we focused on left ventricular diastolic dysfunction in 111 ESRD patients on maintenance peritoneal dialysis, another important predictor of morbidity and mortality, over a 3-year period. At baseline, 39 out of 111 patients (35.1%) had left ventricular diastolic dysfunction. Patients with left ventricular diastolic dysfunction were older with a higher body mass index, higher prevalence of hypertension and diabetes, higher systolic blood pressure but lower diastolic blood pressure compared with those with normal left ventricular diastolic function. After the 3-year study period, despite the preserved left ventricular systolic function, the proportion of patients with left ventricular diastolic dysfunction rose to 44%. Interestingly, decrease in albumin and left atrium strain, larger left atrial volume index and left atrium stiffness, and a worsened body fluid status appeared to be associated deteriorated left ventricular diastolic function. In the last analysis, we showed that residual renal function declined over the 3-year period. Larger left atrium, and left atrial volume index at baseline appeared to be the independent predictors for rapid decline in residual renal function.

In conclusion, we systematic evaluate the cardiovascular system in ESRD patients on peritoneal dialysis over a long period of time. We identified markers such as body volume status, left atrial derived parameters to as power predictors for morbidities and mortality. The identification of these determinants not only shed lights on the insight of pathophysiological process, but may also allow development of new therapeutic strategies targeting these mechanisms.