Characteristics and Prognosis of Wild-Type Transthyretin Amyloid Cardiomyopathy Patients Diagnosed Before 65 Years Old

BACKGROUND: Guidelines recommend screening for transthyretin amyloid cardiomyopathy (ATTR-CM) after age 65 years, yet some patients are diagnosed earlier. OBJECTIVES: The purpose of this study was to compare the proportion, clinical characteristics, and prognosis of wild-type ATTR-CM diagnosed ≤65 years (ATTRwt-Yy) with those diagnosed >65 years (ATTRwt-O). METHODS: Data from the HEAR (Healthcare European Amyloidosis Registry), a multicenter, noninterventional, longitudinal registry, were analyzed. Patients were categorized by age at diagnosis: ATTRwt-Yy (≤65 years) and ATTRwt-O (>65 years). ATTRwt-O patients were further classified by onset of first cardiac symptom: ATTRwt-Oy (≤65 years) and ATTRwt-Oo (>65 years). RESULTS: From July 2021 to May 2024, 3,980 ATTR patients were enrolled; 1,417 had ATTRwt-CM with documented symptom onset. Among them, 67 (4.7%) were ATTRwt-Yy, 111 (7.8%) ATTRwt-Oy, and 1,239 (87.4%) ATTRwt-Oo. Diagnostic delays were 0.65, 20.58, and 0.77 years, respectively (P < 0.001). Heart failure signs at presentation were seen in 34.9% of ATTRwt-Yy, 8.1% of ATTRwt-Oy, and 30.2% of ATTRwt-Oo (P < 0.001). ATTRwt-Yy patients had more extracardiac manifestations, notably osteoarticular disease, whereas rhythm disturbances predominated in ATTRwt-Oy. Median follow-up from diagnosis was 36.2, 23.6, and 22.4 months, respectively. ATTRwt-Yy patients had better survival after diagnosis compared to ATTRwt-O patients. CONCLUSIONS: ATTRwt-CM diagnosed before 65 years shows a distinct phenotype highlighting the need for tailored diagnostic and management strategies.