Management of Cardiac Amyloidosis With Concomitant Left Ventricular Outflow Tract Obstruction.

Cardiac amyloidosis (CA) is a highly morbid cause of heart failure with a poor untreated prognosis. The presence of left ventricular outflow tract (LVOT) obstruction may lead to misclassification of CA as hypertrophic obstructive cardiomyopathy (HOCM). Between 2022 and 2024, 7 patients-4 with light- chain cardiac amyloidosis (AL-CM) and 3 with transthyretin cardiac amyloidosis-initially presented with HOCM at our center (The Johns Hopkins Hospital, Baltimore, Maryland, USA). Diagnostic delay from HOCM to CA diagnosis ranged from 0 to 34 months. Patients with AL-CM had advanced disease (revised Mayo stage III) at the time of CA diagnosis. Six patients required reduction or withdrawal of therapy used for symptomatic LVOT obstruction, and 3 patients were referred for septal reduction therapy. Screening for CA should be considered in older adult patients presenting with HOCM. Symptomatic management of CA with LVOT obstruction is complex given patients' poor tolerance of negatively inotropic medications and the high burden of orthostatic hypotension in patients with CA.