Background: Some dialysis patients have impaired left ventricular (LV) function without coronary artery disease. The pathologic changes and prognoses of these patients have not been well described.
Methods: We performed LV endomyocardial biopsies on 40 hemodialysis patients with dilated cardiomyopathy (DCM; an ejection fraction <50% and a left ventricular end-diastolic volume index >90 mL/m(2) without coronary artery disease), and on 50 nondialysis patients with idiopathic DCM as the control group. Following LV biopsies, the patients were followed-up for a mean of 3.1 +/- 2.3 years.
Results: The pathologic characteristics of the dialysis group were severe myocyte hypertrophy (the mean myocyte diameter across the nucleus: 37.6 +/- 10.5 mum vs. 25.6 +/- 7.7 mum, P= 0.001), myocyte disarray (30%), and extensive fibrosis (the mean percent area of left ventricular fibrosis: 22.3 +/- 18.4% vs. 21.3 +/- 14.6%, P= NS). These pathologic characteristics resembled the dilated phase of hypertrophic cardiomyopathy. In the dialysis group, a high percent area of LV fibrosis was the only significant predictor of cardiac death by multivariate analysis (P= 0.02). The 3-year cumulative event-free survival rate for cardiac death in dialysis patients with severe fibrosis (more than 30%) was 42%, while that for patients without severe fibrosis was 82% (P= 0.03).
Conclusion: The pathologic characteristics of the heart in dialysis patients with DCM are interstitial fibrosis and severe myocyte hypertrophy with occasional disarray. The extent of LV fibrosis is a strong predictor of cardiac death. Careful follow-up and treatment are necessary for dialysis patients with a high percent area of LV fibrosis.