Biventricular endomyocardial fibrosis with right ventricular hypertrabeculation and rapid progression to heart transplantation: imaging and pathologic correlation.

Endomyocardial fibrosis is a restrictive cardiomyopathy characterized by the deposition of fibrotic tissue in the endocardium, predominantly affecting the ventricular apices and atrioventricular valves. Although classically described in endemic regions and low socioeconomic settings, its pathophysiology remains incompletely understood. The coexistence of endomyocardial fibrosis with noncompacted myocardium has not been previously reported. Here, we describe a 57-year-old man, an amateur endurance cyclist, who presented with a two-year history of progressive heart failure symptoms, including fatigue, ascites, and lower limb edema. Transthoracic echocardiography revealed severe biatrial enlargement, grade III diastolic dysfunction, valvular regurgitation, and apical obliteration of both ventricles. Marked right ventricular trabeculation with deep intertrabecular recesses and turbulent flow was observed, raising suspicion of non-compacted myocardium. Despite optimized medical therapy, the patient experienced recurrent hospitalizations and progressed to advanced restrictive heart failure, requiring orthotopic heart transplantation. Pathological examination of the explanted heart confirmed chronic-stage endomyocardial fibrosis with extensive endocardial fibrosis and prominent right ventricular trabeculation. This case demonstrates a previously unreported association between endomyocardial fibrosis and right ventricular hypertrabeculation, expanding the phenotypic spectrum of endomyocardial fibrosis and emphasizing the importance of comprehensive imaging assessment in atypical presentations.