Prevalence of wild–type transthyretin cardiac amyloidosis in elderly subjects from the general population

Abstract Background Wild–type transthyretin cardiac amyloidosis (ATTRwt–CA) affects older adults, and is currently considered as a rare disorder. Objective We investigated for the first time the prevalence of ATTRwt–CA in elderly individuals from the general population. Methods General practitioners from Pisa, Italy, proposed a screening for ATTRwt–CA to all their patients aged 65–90 years, until 1,000 accepted. The following red flags were searched: interventricular septal thickness ≥12 mm, any echocardiographic, ECG or clinical hallmark of CA, or high sensitivity–troponin T ≥14 ng/L. Individuals with at least one red flag (n=346) were asked to undergo the search for a monoclonal protein and bone scintigraphy, and 216 accepted. Results Four patients received a non–invasive diagnosis of ATTRwt–CA. All complained of dyspnoea on moderate effort. A woman and a man aged 79 and 85 years, respectively, showed an intense cardiac tracer uptake (grade 3), left ventricular (LV) wall thickening, grade 2 to 3 diastolic dysfunction, and N–terminal pro–B–type natriuretic peptide (NT–proBNP) >1,000 ng/L. Two other patients (a man aged 74 years and a woman aged 83 years) showed a grade 2 uptake, an increased LV septal thickness, but preserved diastolic function, and NT–proBNP <300 ng/L. The prevalence of ATTR–CA in subjects ≥65 years was calculated as 0.46% (i.e., 4 out of the 870 subjects completing the screening, namely 654 not meeting the criteria for Step 2 and 216 progressing to Step 2). Conclusions ATTRwt–CA has a prevalence of 0.46% in elderly subjects from the general population.