BACKGROUND: Considering the increased prevalence of heart failure with preserved ejection fraction (HFpEF) as a result of the aging population, the pathophysiology of HFpEF needs to be examined. Furthermore, many comorbidity profiles in patients with HFpEF have been reported. Hypertrophic cardiomyopathy is a well-known specific etiology of HFpEF. Cardiac amyloidosis, which mimics infiltrative and hypertrophic cardiomyopathy, resulting from intensive amyloid deposition, is easily overlooked.

CASE REPORT: A 53-year-old man with a 2-week history of persistent breathlessness was referred to our hospital. Upon admission, transthoracic echocardiography showed concentric mild left ventricular (LV) hypertrophy without a characteristic granular sparkling appearance or pericardial effusion, preserved ejection fraction, and bi-atrial enlargement with normal ventricular chambers. Doppler-derived LV diastolic filling demonstrated a prominent restrictive pattern indicating LV stiffness and elevated LV filling pressure. Blood tests revealed severe elevation of B-type natriuretic peptide and marked elevation of immunoglobulin E without eosinophilia. He was diagnosed with primary amyloid light-chain (AL) amyloidosis via skin and endomyocardial biopsy.

CONCLUSIONS: We encountered a rare case of hypertrophic cardiomyopathy with HFpEF and identified a Doppler-derived restrictive filling pattern suggestive of early-stage heart failure in infiltrative cardiomyopathies. We suggest that infiltrative cardiomyopathies, such as cardiac amyloidosis, should be considered if hypertrophic cardiomyopathy is observed in a patient with HFpEF.

Keywords: Cardiomyopathy, Hypertrophic - diagnosis, Amyloidosis - diagnosis, Diagnosis, Differential, Dyspnea - etiology, Heart Diseases - diagnosis, Hypergammaglobulinemia - etiology, Immunoglobulin E - blood, Stroke Volume