**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.**
Robert Adam, Emergency Institute for Cardiovascular Diseases Prof. Dr. C.C. Iliescu and Carol Davila University of Medicine and Pharmacy, Bucharest, Romania

**Main Body of the Abstract**
Aims:We aimed to investigate which parameters of left atrial (LA) structure and function could predict new-onset atrial arrhythmias (NOAA) in patients with CA, aiding in improved follow-up.
Methods and Results: We prospectively included patients diagnosed with CA, both light chain (AL) and variant transthyretin (ATTRv) with no history of AA. LA mechanical dispersion (LAMD) was defined as the standard deviation of time-to-peak positive strain and reported as percentage from the R-R interval. The primary outcome was NOAA. 93 patients were included (mean age 54.3±9.8, 58% males), and 44 patients (47%) developed NOAA during a median follow up of 11 (3.5-36.0) months. Patients with NOAA had heavier hearts, worse global LV function, more LV longitudinal impairment, larger atria and worse LA function. LA reservoir strain (LASr) was significantly lower and LAMD significantly higher in patients who developed NOAA. In the multivariate analysis adjusting for confounding factors, a lower LAMD was independently associated with higher risk for NOAA (HR: 1.182, 95% CI: 1.033-1.351, p= 0.015). Patients with LAMD> 6.6% had a higher risk for NOAA than those with LAMD≤ 6.6% (P<0.001). Furthermore, LAMD> 6.6% remained an independent predictor for NOAA in both univariate and multivariate analysis. Five models were created and the model based on LA volume was significantly improved by adding LVGLS, RVFWS and LAMD, but it was not significantly improved by adding LASr.
Conclusion: LAMD is a novel, reproducible and independent predictor of NOAA in patients with CA, being superior and incremental to other imaging predictors.



**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.**
Robert Adam, Emergency Institute for Cardiovascular Diseases Prof. Dr. C.C. Iliescu and Carol Davila University of Medicine and Pharmacy, Bucharest, Romania

**Main Body of the Abstract**
**Aims:**We aimed to investigate which parameters of left atrial (LA) structure and function could predict new-onset atrial arrhythmias (NOAA) in patients with CA, aiding in improved follow-up.
**Methods and Results:** We prospectively included patients diagnosed with CA, both light chain (AL) and variant transthyretin (ATTRv) with no history of AA. LA mechanical dispersion (LAMD) was defined as the standard deviation of time-to-peak positive strain and reported as percentage from the R-R interval. The primary outcome was NOAA. 93 patients were included (mean age 54.3±9.8, 58% males), and 44 patients (47%) developed NOAA during a median follow up of 11 (3.5-36.0) months. Patients with NOAA had heavier hearts, worse global LV function, more LV longitudinal impairment, larger atria and worse LA function. LA reservoir strain (LASr) was significantly lower and LAMD significantly higher in patients who developed NOAA. In the multivariate analysis adjusting for confounding factors, a lower LAMD was independently associated with higher risk for NOAA (HR: 1.182, 95% CI: 1.033-1.351, p= 0.015). Patients with LAMD> 6.6% had a higher risk for NOAA than those with LAMD≤ 6.6% (P<0.001). Furthermore, LAMD> 6.6% remained an independent predictor for NOAA in both univariate and multivariate analysis. Five models were created and the model based on LA volume was significantly improved by adding LVGLS, RVFWS and LAMD, but it was not significantly improved by adding LASr.
**Conclusion**: LAMD is a novel, reproducible and independent predictor of NOAA in patients with CA, being superior and incremental to other imaging predictors.



Left atrial mechanical dispersion as a novel predictor biomarker of new-onset atrial arrhythmias in cardiac amyloidosis PB136 (#508)

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.