**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.**
Mariana Pinheiro Xerfan Corso, Heart Institute, University of Sao paulo (INCOR-HCFMUSP), Departament of Cardiopneumology, Sao paulo - SP - Brazil. Contact information: mpxerfan@usp.br or dramarianaxerfan@gmail.com

**Main Body of the Abstract**
BACKGROUND: 99mTechnetium-pyrophosphate Cardiac Scintigraphy(CS) has been repurposed for the diagnosis of transthyretin amyloid cardiomyopathy(ATTR-CM) when combined with blood/urine tests to exclude monoclonal protein,with high specificity and positive predictive value near 100%. CASE REPORT:A 38y-old afro-descendant male with an important family history of sudden death and a 10year history of several syncopes,dysautonomia and sensitive neuropathy, presented in 2016 to the ER with unstable bradycardia in need of a pacemaker. Four years later he presented ventricular arrhythmias in-need of an ICD implantation. Echocardiogram ventricular function was preserved,with diffuse myocardial hypertrophy(21mm diameter);MRI demonstrated a ring-like pattern with multifocal myocardial delayed enhancement and 82g fibrosis(37% of the ventricular mass).In 2023 Echocardiogram showed diffuse hypokinesis and lower ventricular ejection fraction=45% with hyper-refringent myocardium and restrictive hemodynamics. Although there were several clinical red flags for amyloidosis and the 2023 CS were positive (grade 3)and highly suggestive of ATTR-CM, genetic testing determined a variant on FLNC gene that combined with the epidemiology and hypertrophic phenotype actually presented us a False Positive of the CS. DECISION-MAKING: False-positive tests in CS have been described secondary to hydroxychloroquine. Recently, it has also been shown in publications with hypertrophic cardiomyopathy spectrum of patients. CONCLUSION: As CS scans are increasingly applied to broader populations of thick heart cardiomyopathies, this case-report highlights the potential for false-positive results.



**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.**
**Mariana Pinheiro Xerfan Corso, Heart Institute, University of Sao paulo (INCOR-HCFMUSP), Departament of Cardiopneumology, Sao paulo - SP - Brazil. Contact information: mpxerfan@usp.br or dramarianaxerfan@gmail.com**

**Main Body of the Abstract**
**BACKGROUND:** 99mTechnetium-pyrophosphate Cardiac Scintigraphy(CS) has been repurposed for the diagnosis of transthyretin amyloid cardiomyopathy(ATTR-CM) when combined with blood/urine tests to exclude monoclonal protein,with high specificity and positive predictive value near 100%. **CASE REPORT:**A 38y-old afro-descendant male with an important family history of sudden death and a 10year history of several syncopes,dysautonomia and sensitive neuropathy, presented in 2016 to the ER with unstable bradycardia in need of a pacemaker. Four years later he presented ventricular arrhythmias in-need of an ICD implantation. Echocardiogram ventricular function was preserved,with diffuse myocardial hypertrophy(21mm diameter);MRI demonstrated a ring-like pattern with multifocal myocardial delayed enhancement and 82g fibrosis(37% of the ventricular mass).In 2023 Echocardiogram showed diffuse hypokinesis and lower ventricular ejection fraction=45% with hyper-refringent myocardium and restrictive hemodynamics. Although there were several clinical red flags for amyloidosis and the 2023 CS were positive (grade 3)and highly suggestive of ATTR-CM, genetic testing determined a variant on FLNC gene that combined with the epidemiology and hypertrophic phenotype actually presented us a False Positive of the CS. **DECISION-MAKING:** False-positive tests in CS have been described secondary to hydroxychloroquine. Recently, it has also been shown in publications with hypertrophic cardiomyopathy spectrum of patients. **CONCLUSION:** As CS scans are increasingly applied to broader populations of thick heart cardiomyopathies, this case-report highlights the potential for false-positive results.



A false positive 99mTechnetium-pyrophosphate Cardiac Scintigraphy in a suspected case of cardiac amyloidosis with FLNC variant. PB133 (#502)

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.