Prevalence and clinical outcomes of transthyretin amyloidosis: a systematic review and meta-analysis

Aim Systematic evidence on the prevalence and clinical outcome of transthyretin amyloidosis (ATTR) is missing. We explored: (i) the prevalence of cardiac amyloidosis in various patient subgroups, (ii) survival estimates for ATTR subtypes, and (iii) the effects of novel therapeutics on the natural course of disease. Methods and results A systematic review of literature published in MEDLINE before 31 December 2021 was performed for the prevalence of cardiac amyloidosis and all-cause mortality of ATTR patients. Extracted data included sample size, age, sex, and all-cause mortality at 1, 2, and 5 years. Subgroup analyses were performed for ATTR subtype, that is, wild-type ATTR (wtATTR) versus hereditary ATTR (hATTR), hATTR genotypes, and treatment subgroups. We identified a total of 62 studies (n = 277 882 individuals) reporting the prevalence of cardiac amyloidosis, which was high among patients with a hypertrophic cardiomyopathy phenotype, heart failure with preserved ejection fraction, and the elderly with aortic stenosis. Data on ATTR mortality were extracted from 95 studies (n = 18 238 ATTR patients). Patients with wtATTR were older (p = 7 x 10(-10)) and more frequently male (p = 5 x 10(-20)) versus hATTR. The 2-year survival of ATTR was 73.3% (95% confidence interval [CI] 70.9-75.7); for non-subtyped ATTR 70.4% (95% CI 66.9-73.9), for wtATTR 76.0% (95% CI 73.0-78.9]) and for hATTR 77.2% (95% CI 74.0-80.4); in meta-regression analysis, wtATTR was associated with higher survival after adjusting for confounders. There was an interaction between survival and hATTR genotypes (p = 10(-15), Val30Met having the lowest and Val122Ile/Thr60Ala the highest mortality). ATTR 2-year survival was higher on tafamidis/patisiran compared to natural disease course (79.9%, 95% CI 74.4-85.3 vs. 72.4%, 95% CI 69.8-74.9, p < 0.05). Conclusions We report the prevalence of ATTR in various population subgroups and provide survival estimates for the natural course of disease and the effects of novel therapeutics. Important gaps in worldwide epidemiology research in ATTR were identified.