Immunohistochemical Study of Remodeling of Myocardial Lymphatic and Blood Microvascular Structures in Terminal Heart Failure: Differences Between Ischemic and Dilated Cardiomyopathy

This study investigated (cardiac) remodeling of the myocardial microvasculature in patients with terminal heart failure due to ischemic (ICM) and dilative (DCM) cardiomyopathy. Seventeen transmural left-ventricular (LV) biopsies (9 ICM and 8 DCM), taken from heart transplant recipients at transplantation (n=4) or during ventricular assist device implantation (n=13) were investigated by immunohistostaining for VEGFR-1 and VEGFR-2 as capillary markers and VEGFR-3, D2-40, PROX-1 and LYVE-1 as lymphatic markers. Results were compared to LV biopsies from 7 donor hearts (control). Compared to control, DCM hearts showed a significantly higher density of LYVE-1 positive lymphatics (p < 0.05), whereas no difference was seen for other markers. ICM hearts showed a significantly higher density of D2-40 positive lymphatics (p < 0.01) and a lower density of VEGFR-2 capillaries compared to control (p < 0.05). In comparison to normal donor hearts, ICM and DCM hearts showed a significantly different pattern of microvascular receptor expression. As distinct patterns were seen in ICM and DCM, the effect of microvascular remodeling may be substantially different between two clinically important causes of cardiomyopathy. Further research should be aimed at defining the impact of extracellular matrix composition and VEGF-related angiogenesis on the myocardial microvasculature at various stages of heart failure.