Cardiomyopathy with Prominent Autophagic Degeneration, Accompanied by an Elevated Plasma Brain Natriuretic Peptide Level Despite the Lack of Overt Heart Failure

Abstract

A 75-year-old man without overt heart failure showed an abnormally high level of brain natriuretic peptide (BNP) in plasma: 600 pg/ml. The left ventricular endomyocardial biopsy revealed prominent vacuolar degeneration in the myocytes, most of which were positive for PAS stain and BNP immunoreaction. Ultrastructurally, degenerative changes of myocytes were marked, such as deposits of glycogen and lipofuscin granules in the cytoplasm, but the most prominent finding was giant vacuoles containing degraded mitochondria, glycogen granules, myofibrils, and myelin-like structures (autophagosomes). This case may belong to one of the unclassified cardiomyopathies characterized by prominent autophagic vacuoles.