Abstract 2957: Histological Markers of Myocardial Improvement During Left Ventricular Assist Device Support
Background: Left ventricular assist devices (LVADs) unload the failing heart initiating mechanisms that lead to improvement in hemodynamic function as well as cellular and tissue architecture. In a group of patients improvement allowed LVAD removal (n= 8; 6 men, 2 women). Clinical and histological parameters were compared with a paired group of patients that remained on support without evidence of clinical remission (n=9; 8 men, 1 woman).
Objective: Determine histological features of patients with a favorable clinical course that allowed LVAD weaning and compare them with patients that remained on support or required transplant.
Methods: All patients (n= 17) underwent LVAD implantation for heart failure due to idiopathic cardiomyopathy. There was no significant difference among the groups in mean age (24.1 vs. 25 y/o, p = 0.4) or mean time on LVAD (506 vs. 414 days, p = 0.24). Left ventricular cores at implantation were studied according to a grading scale we designed to evaluate severity and extent of fibrosis and hypertrophy. Findings were correlated with a computerized semi-quantitative analysis of Picro-Sirius Red and Masson trichrome. Measurements were performed on ≥ 5 sections of randomly selected areas. Fibrosis evaluation included interstitial (10x), perivascular (20x) and replacement (4x). Hypertrophy parameters were myocyte diameter, cytoplasmic area and nuclear/cytoplasmic ratio (N/C). Statistical analysis compared histological differences between the groups.
Results: All parameters showed significantly less hypertrophy in the pump-removal group (Mean cytoplasmic area, removal = 57.99μ2 vs. non-removal = 77.18μ2, p = 0.002; mean myocyte diameter, removal = 20.31μ vs. non-removal = 25.35μ, p = 0.004; mean N/C removal= 11.03 vs. non-removal = 8.68, p = 0.053). The pump-removal group showed less overall fibrosis (Mean fibrosis removal = 11.57% vs. non-removal = 13.24%, p = 0.28), but the difference did not reach the level of significance of hypertrophy parameters.
Conclusions: Weaned patients showed an overall trend of less hypertrophy and fibrosis compared with patients that remained on support. Correlation of histology with clinical parameters may help define patients with higher probability of LVAD removal and myocardial recovery.