Long-term evolution of cardiomyopathy in dialysis patients.

BACKGROUND: Left ventricular enlargement is very common at the inception of dialysis therapy, and highly predictive of future cardiac morbidity and mortality. It is not known whether cardiac size increases further while on dialysis therapy and whether potentially reversible risk factors for later progression can be identified. METHODS; Baseline and yearly echocardiograms were performed in a prospective inception cohort of 433 dialysis patients. The mean patient follow-up was 41 months; 29 patients had four consecutive echocardiograms at yearly intervals.
RESULTS: The patient subset with four echocardiograms was older (58 vs. 51 years, P = 0.02) and had a lower mass ventricular mass index (128 vs. 149 g/m2, P = 0.02) than the parent group. Using repeated measures analysis of variance, applied to those with four echocardiograms, there were progressive increases over time in posterior wall thickness (P = 0.015), left ventricular end-diastolic diameter, left ventricular mass index (P = 0.001), and cavity volume index (P = 0. 001). Mass-to-volume ratios did not change. The biggest changes in mass (18 g/m2 - 14%)and volume index (13 ml/m2 - 18%) occurred between baseline and year 1, although increases in both were seen after year 1. Hemodialysis versus peritoneal dialysis (41 g/m2, P = 0.008) and anemia (10 g/m2 per 1 g/dl drop in hemoglobin, P = 0.02) were associated with progressive left ventricular enlargement, but only within the first year of dialysis therapy. The left ventricular enlargement seen after year 1 was independent of anemia, blood pressure, serum albumin and mode of dialysis.
CONCLUSIONS: Progressive cardiac enlargement, particularly left ventricular dilation with compensatory hypertrophy, continues after starting dialysis therapy. Most of the additional cardiac enlargement seems to occur in the first year of dialysis therapy, suggesting that intervention beyond one year may be relatively ineffective.