Myocardial Oxygen Consumption and Efficiency in Patients With Cardiac Amyloidosis

Background This study evaluated myocardial oxygen consumption (MVO2) and myocardial external efficiency (MEE) in patients with cardiac amyloidosis (CA). Furthermore, we compared MEE and MVO2 in subjects with light chain amyloidosis versus transthyretin (ATTR) amyloidosis. Methods and Results The study population comprised 40 subjects: 25 patients with confirmed CA and 15 control subjects. All subjects underwent an 11C‐acetate positron emission tomography. Furthermore, the CA patients underwent comprehensive echocardiography and right heart catheterization during a symptom‐limited, semi‐supine exercise test. MEE was calculated from 11C‐acetate positron emission tomography as the ratio of left ventricular (LV) stroke work and the energy equivalent of MVO2. Myocardial work efficiency was calculated as echocardiography‐derived work pressure product divided by three‐dimensional LV mass. CA patients had significantly lower LV‐ejection fraction (54±13% versus 63±4%, P