Transthyretin cardiac amyloid: Broad heart failure phenotypic spectrum and implications for diagnosis

Aims: Transthyretin cardiac amyloidosis (ATTR-CA) is most often associated with heart failure with preserved ejection fraction (HFpEF). However, patients may present with impaired systolic function at the time of diagnosis, which has not been widely investigated. We sought to explore the prevalence of various heart failure (HF) phenotypes and their associated clinical characteristics at the time of ATTR-CA diagnosis. Methods: We performed a single-centre retrospective cohort study of consecutive patients with ATTR-CA evaluated between February 2016 and December 2022. Data on patient demographics, comorbidities, imaging and laboratory findings were compared across HF phenotypes (age: 78.1 ± 8.6 years, with 91.1% male). A total of 21.6% (n = 46) presented with heart failure with reduced ejection fraction (HFrEF), 17.8% (n = 38) with heart failure with mildly reduced ejection fraction (HFmrEF) and 60.6% (n = 129) with HFpEF at the time of diagnosis with ATTR-CA. Those presenting with HFrEF or HFmrEF were more likely to be African American and had significantly worse New York Heart Association (NYHA) functional class, higher N-terminal pro-brain natriuretic peptide (NT-proBNP) and higher serum creatinine levels as compared with those with HFpEF. Conclusions: Although ATTR-CA is traditionally thought to be seen primarily among patients with HFpEF, our data suggest that ATTR-CA has a higher prevalence among patients with HFrEF, which underscores the importance of heightened clinical suspicion regardless of ejection fraction when considering ATTR-CA. Furthermore, although comorbidities are similar, patients with HFmrEF and HFrEF had a worse symptom burden.