**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.**
Maria Koutelou, MD, PhD, MSc,  Nuclear Medicine Department Onassis Cardiac Surgery Center, Athens, Greece, 356 Sygrou Avenue, 17674 Kallithea, email: marinucl@hotmail.com

**Main Body of the Abstract**
Introduction
Transthyretin amyloidosis (ATTR) is a rare yet impactful infiltrative disease. Utilizing DPD myocardial scintigraphy has emerged as a non-invasive, highly sensitive, and specific diagnostic tool for cardiac ATTR amyloidosis. However, instances exist where additional investigations reveal alternative conditions, such as AL amyloidosis. This study draws on experiences from the Onassis Cardiac Surgery Center and the monitoring center for infiltrative myocardial diseases at AHEPA's cardiology clinic.
Materials and Methods
Patients with suspected cardiac or extracardiac amyloidosis undergo Tc-99m DPD myocardial scintigraphy. Over 500 patients have been examined, and further diagnostic steps, including laboratory investigations and invasive techniques, are based on clinical and imaging findings (e.g., biopsy).
Results
Among 76 patients with positive myocardial scintigraphy (Grade 2 or 3 per Perugini scale), 8 were confirmed to have AL Amyloidosis during investigations into paraproteinemia. Three patients exhibited Grade 3 uptake, while the others showed Grade 2 or 2 to 3. Notably, one patient displayed diffuse radiopharmaceutical uptake in soft tissues without cardiac involvement, prompting κ and λ light chain analysis and immunostaining, leading to the diagnosis of AL amyloidosis.
Conclusion
While cardiac DPD scintigraphy plays crucial role in diagnosing cardiac amyloidosis from transthyretin, a positive result should not automatically imply ATTR amyloidosis. Crucially, differentiating between ATTR and AL amyloidosis is vital, given the significant implications for prognosis and therapeutic strategies. Laboratory exclusion of paraproteinemia is an essential step in the diagnostic algorithm for ATTR amyloidosis, especially since over 20% of patients with Grade 3 and 2 uptake may have underlying AL amyloidosis.



**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.**
Maria Koutelou, MD, PhD, MSc,  Nuclear Medicine Department Onassis Cardiac Surgery Center, Athens, Greece, 356 Sygrou Avenue, 17674 Kallithea, email: marinucl@hotmail.com

**Main Body of the Abstract**
**Introduction**
Transthyretin amyloidosis (ATTR) is a rare yet impactful infiltrative disease. Utilizing DPD myocardial scintigraphy has emerged as a non-invasive, highly sensitive, and specific diagnostic tool for cardiac ATTR amyloidosis. However, instances exist where additional investigations reveal alternative conditions, such as AL amyloidosis. This study draws on experiences from the Onassis Cardiac Surgery Center and the monitoring center for infiltrative myocardial diseases at AHEPA's cardiology clinic.
**Materials and Methods**
Patients with suspected cardiac or extracardiac amyloidosis undergo Tc-99m DPD myocardial scintigraphy. Over 500 patients have been examined, and further diagnostic steps, including laboratory investigations and invasive techniques, are based on clinical and imaging findings (e.g., biopsy).
**Results**
Among 76 patients with positive myocardial scintigraphy (Grade 2 or 3 per Perugini scale), 8 were confirmed to have AL Amyloidosis during investigations into paraproteinemia. Three patients exhibited Grade 3 uptake, while the others showed Grade 2 or 2 to 3. Notably, one patient displayed diffuse radiopharmaceutical uptake in soft tissues without cardiac involvement, prompting κ and λ light chain analysis and immunostaining, leading to the diagnosis of AL amyloidosis.
**Conclusion**
While cardiac DPD scintigraphy plays crucial role in diagnosing cardiac amyloidosis from transthyretin, a positive result should not automatically imply ATTR amyloidosis. Crucially, differentiating between ATTR and AL amyloidosis is vital, given the significant implications for prognosis and therapeutic strategies. Laboratory exclusion of paraproteinemia is an essential step in the diagnostic algorithm for ATTR amyloidosis, especially since over 20% of patients with Grade 3 and 2 uptake may have underlying AL amyloidosis.



Positive cardiac scintigraphy with Tc-99m DPD-SPECT: Diagnosis is not always ATTR cardiac amyloidosis PA53 (#61)

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.