**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Sergi Yun; Bio-Heart Cardiovascular Diseases Research Group, Bellvitge Biomedical Research Institute (IDIBELL), Bellvitge University Hospital, L'Hospitalet de Llobregat, Spain; syunvi@gmail.com

**Main Body of the Abstract**
Background: Transthyretin amyloid cardiomyopathy (ATTR-CM) often presents as heart failure (HF) with preserved or mildly reduced ejection fraction (HFpEF or HFmrEF). Given that ATTR-CM is underdiagnosed, its true prevalence is uncertain.
Methods: An international epidemiology study (December 2020–June 2023) that enrolled patients aged ≥60 years with a history of HF, left ventricular ejection fraction (LVEF) >40%, end diastolic interventricular septum thickness (EDIVST) ≥12 mm, and without history of HF with reduced ejection fraction, amyloidosis, cardiomyopathy of known cause, or severe valvular or coronary heart disease. ATTR-CM was determined using cardiac scintigraphy with exclusionary testing for light chain amyloidosis. The study was terminated early without safety concerns.
Results: Of the 347 patients enrolled (mean age 78 years [SD: 8.2]; 53% male; 86% White; 66% New York Heart Association class II; mean LVEF 58% [8.3]), 63% were in Europe (31% North America; 7% Asia). Scintigraphy results were unevaluable in 32 patients. Of the 259 patients without ATTR-CM, 235 had grade 0, and 24 had grade 1 tracer uptake (none received biopsy). 56/315 (18%) evaluable patients had ATTR-CM (scintigraphy grade 2, n=8; grade 3, n=48), including 24% (50/210) in Europe, 5% (4/83) in North America, and 9% (2/22) in Asia. Mean (SD) EDIVST was higher in patients with vs without ATTR-CM (16 mm [2.6] vs 14 mm [2.4]; P<0.0001)
Conclusions: Internationally, 18% of evaluable high-risk patients with HFpEF or HFmrEF were found to have previously undiagnosed ATTR-CM. Regional variability in our findings may reflect differences in recruitment centers or patient characteristics. NCT04424914



**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Sergi Yun; Bio-Heart Cardiovascular Diseases Research Group, Bellvitge Biomedical Research Institute (IDIBELL), Bellvitge University Hospital, L'Hospitalet de Llobregat, Spain; [syunvi@gmail.com](mailto:syunvi@gmail.com)

**Main Body of the Abstract**
Background: Transthyretin amyloid cardiomyopathy (ATTR-CM) often presents as heart failure (HF) with preserved or mildly reduced ejection fraction (HFpEF or HFmrEF). Given that ATTR-CM is underdiagnosed, its true prevalence is uncertain.
Methods: An international epidemiology study (December 2020–June 2023) that enrolled patients aged ≥60 years with a history of HF, left ventricular ejection fraction (LVEF) >40%, end diastolic interventricular septum thickness (EDIVST) ≥12 mm, and without history of HF with reduced ejection fraction, amyloidosis, cardiomyopathy of known cause, or severe valvular or coronary heart disease. ATTR-CM was determined using cardiac scintigraphy with exclusionary testing for light chain amyloidosis. The study was terminated early without safety concerns.
Results: Of the 347 patients enrolled (mean age 78 years [SD: 8.2]; 53% male; 86% White; 66% New York Heart Association class II; mean LVEF 58% [8.3]), 63% were in Europe (31% North America; 7% Asia). Scintigraphy results were unevaluable in 32 patients. Of the 259 patients without ATTR-CM, 235 had grade 0, and 24 had grade 1 tracer uptake (none received biopsy). 56/315 (18%) evaluable patients had ATTR-CM (scintigraphy grade 2, n=8; grade 3, n=48), including 24% (50/210) in Europe, 5% (4/83) in North America, and 9% (2/22) in Asia. Mean (SD) EDIVST was higher in patients with vs without ATTR-CM (16 mm [2.6] vs 14 mm [2.4]; P<0.0001)
Conclusions: Internationally, 18% of evaluable high-risk patients with HFpEF or HFmrEF were found to have previously undiagnosed ATTR-CM. Regional variability in our findings may reflect differences in recruitment centers or patient characteristics. NCT04424914



International prevalence of transthyretin amyloid cardiomyopathy in high-risk patients with heart failure and preserved or mildly reduced ejection fraction PB48 (#3)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.