C61 RAREFACTION OF MYOCARDIAL LYMPHATIC VESSELS IN PATIENTS WITH CARDIAC AMYLOIDOSIS

Abstract Introduction In cardiac amyloidosis (CA), amyloid fibers accumulate in the extracellular spaces of heart, causing a compression and obliteration lymphatic vessels, possibly their disappearance. As lympathic drainage removes proteins from interstitial spaces, including precursors, an impairment vessels could exacerbate accumulation, triggering vicious circle. Methods Lymphatic were visualized by immunohistochemistry using monoclonal antibody against podoplanin (D2–40, marker endothelial cells) immunopreroxidase technique. We investigated 3 groups cases: 1) as reference standard, endomyocardial specimens left ventricular (LV) endomyocardium 10 heart valve donors, deceased for trauma and/or cerebral hemorrhage, with no evidence disease on gross microscopic examination; 2) 15 consecutive LV biopsies (EMBs) patients CA, where was detected typed Congo red staining, proteomics, 3) 13 surgical septal hypertrophy, undergoing aortic surgery CA excluded histology. Results donor hearts (n=10), mostly distributed subendocardial subepicardial layers, some intra–myocardial near larger blood vessels. then examined (amyloid transthyretin [ATTR]–CA, n=10; light–chain [AL]–CA, n=5; 50% men, median age 75 years [interquartile range 71–78]), (55% 68 [59–71]). The density 0.52 vessels/mm2 (0–3.32), vs. 10.90 (3.10–26.25) those without (p=0.001). No significant differences found mass index (p=0.170) or ejection fraction (p=0.262). Three ATTR–CA 2 AL–CA showed EMB. did not differ significantly ATTR– AL–CA. Conclusions Patients have decreased endo–myocardial compared to despite difference degree wall thickening fraction. These results support hypothesis that is deranged promoting further deposition.