Prognostic value of CMR-derived extracellular volume in AL amyloidosis: a multicenter study

Background: This study aimed to assess the prognostic value of cardiac magnetic resonance (CMR) variables and compare them with biological and echocardiographic markers in patients with AL cardiac amyloidosis (CA). Methods: We conducted a prospective study across three tertiary centres, where patients underwent clinical examination, blood tests, echocardiography, and CMR. The primary endpoint was all-cause mortality. Results: A total of 176 patients with AL CA were included, with a median age of 68 years (IQR 58-75). According to the 2004 Mayo Clinic staging, 121 patients (69%) were in stage 3. During a median follow-up of 22 months (IQR 8-48), 45 patients died, and 55 were hospitalized for heart failure. Patients who died had higher NT-proBNP and troponin levels, and lower LVEF, cardiac output, and longitudinal strain. Among CMR variables, extracellular volume (ECV) was most strongly associated with all-cause mortality. In multivariate Cox models, including Mayo Clinic staging, ECV ≥ 0.45 was independently associated with mortality (HR 2.36, CI 95% 1.47-5.60) and also with heart failure hospitalizations (HR 4.10, 95%CI 2.15-8.8). Conclusion: ECV is a powerful predictor of outcomes in AL CA, providing additional prognostic value on top of Mayo Clinic staging.