Degree of cardiac fibrosis and hypertrophy at time of implantation predicts myocardial improvement during left ventricular assist device support

Background: There have been increasing reports of cardiac improvement in heart failure patients supported by left ventricular assist devices (LVADs i.e.), including a number of patients who have tolerated removal of the device without the benefit of cardiac transplant. In the current study, we retrospectively investigated echocardiographic and histologic changes in patients supported by LVADs (n = 18). The goal of our study was to determine if the degree of cardiac fibrosis and myocyte size in pre-implant biopsies could predict myocardial improvement as assessed by improvements in ejection fraction (EF) during LVAD support. Methods: We determined total collagen content in myocardial biopsy specimens by a semi-quantitative analysis of positive Picro-Sirius Red-stained areas and myocyte size measurements by computerized edge detection software. Results: During LVAD support, 9 of the 18 patients (Group A) were distinguished by significant improvement in ejection fraction (pre <20% vs unloaded 34 ± 5%). In addition, Group A patients had significantly less fibrosis and smaller myocytes than their Group B counterparts, whose EF did not improve. There was an inverse correlation between pre-implant biopsy collagen levels and myocyte size with increases in EF during LVAD unloading. Conclusions: We found that the patients who demonstrated the greatest improvements in EF during support had less fibrosis and smaller myocytes at the time of device implantation. We propose that tissue profiling a patient's pre-implant biopsy for fibrosis and myocyte size may allow stratification in Stage IV heart failure and may predict myocardial improvement during LVAD support.