**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.**
Hilda Gonzalez Bonilla. Division of Cardiovascular Diseases, Mayo Clinic, Rochester MN. Research collaborator.

**Main Body of the Abstract**
Non-invasive diagnosis of ATTR cardiac amyloidosis (CA) can be established using bone scintigraphy (BS) according to consensus guidelines. We present a case series of patients who were misdiagnosed with ATTR-CA using the non-invasive pathway and were prescribed and/or treated with Tafamidis.
Twenty-six patients were identified from five referral centers. Eighteen (69.2%) were male and median age was 69 years. Twenty-five (96.1%) reported at least one symptom suggestive of CA (Table). Echocardiogram was performed in all, 18 (69.2%) had at least one feature suggestive of CA. Seven of the 12 (46.1%) who had cardiac magnetic resonance (CMR) performed had at least one feature suggestive of CA. Six (23.1%) did not have any feature suggestive of CA on echocardiogram or CMR. All patients had BS that was interpreted as positive in the initial institution. However, 19 (73.1%) of the previously reported positive BS were interpreted as negative at an amyloid referral center, two had an equivocal BS. Eight of 26 did not have SPECT performed with initial BS. Six patients were diagnosed with AL rather than ATTR, in these cases monoclonal protein studies performed at the initial institution were incomplete or misinterpreted.
Almost 25% of patients in this study were found to have AL, highlighting the potentially fatal nature of misdiagnosis using the non-invasive pathway. The remaining patients did not have a diagnosis of amyloidosis after evaluation at a referral center. This study highlights the perils of the non-invasive pathway of ATTR diagnosis if consensus guidelines are not followed.



Mistreatment with Tafamidis for Erroneous Diagnosis of ATTR Cardiac Amyloidosis: Case Series PB76 (#334)

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.