Tissue is the Issue: Endomyocardial Biopsy Characterization of Heart Failure with Preserved Ejection Fraction and Incident Cardiac Amyloidosis

Introduction Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous disease with no proven pharmacologic therapies. Cardiac amyloidosis shares common features of HFpEF, however endomyocardial biopsy data are only available on limited subsets of HFpEF patients. To our knowledge, this is the first study to comprehensively characterize biopsy data for patients referred for HFpEF evaluation. Methods We included patients referred to the Johns Hopkins HFpEF Clinic who underwent right heart catheterization and endomyocardial biopsy. HFpEF diagnosis was based on signs and symptoms of HF, LVEF ≥50%, and at least 2 of the following: 1) structural heart disease by echocardiogram, 2) invasive hemodynamics with elevated pulmonary capillary wedge pressure, or 3) NT-proBNP >100 pg/mL. We excluded patients with severe valvular heart disease, known infiltrative or restrictive cardiomyopathy, or constrictive pericarditis. We evaluated clinical characteristics, hemodynamics, echocardiography, and histology. Cardiac amyloidosis was diagnosed on Congo red stain if greater than mild deposition was present. Data were analyzed using median tests or Fisher's exact tests. Results Of 108 HFpEF patients, cardiac amyloidosis was diagnosed in 15 patients (14%). Non-amyloid HFpEF patients had high incidence of myocyte hypertrophy and fibrosis on endomyocardial biopsy (Figure). HFpEF-Amyloid were older (74y v. 65y, p Conclusions Endomyocardial biopsy diagnosed cardiac amyloidosis in 14% of HFpEF patients not suspected to have amyloidosis, with markedly different characteristics between the subgroups. These findings have important diagnostic and therapeutic implications given recent advances in therapies for cardiac amyloidosis.