The study looked at people with a heart disease called wild‑type transthyretin amyloid cardiomyopathy (ATTRwt‑CM) who were diagnosed before age 65. It found that early‑diagnosed patients make up a small slice of all cases, tend to have more joint and bone problems, and are diagnosed much faster than older patients. Their survival after diagnosis is better than those diagnosed later.

Guidelines recommend screening for transthyretin amyloid cardiomyopathy (ATTR-CM) after age 65 years, yet some patients are diagnosed earlier. 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). 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). 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. ATTRwt-CM diagnosed before 65 years shows a distinct phenotype highlighting the need for tailored diagnostic and management strategies.