**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.**
Giuseppe Damiano Sanna
1. Amyloidosis Research and Treatment Center, Department of Molecular Medicine, Foundation IRCCS Policlinico San Matteo, Pavia (Italy)
2. Clinical and Interventional Cardiology, Sassari University Hospital, Sassari (Italy)

**Main Body of the Abstract**
Data regarding evolution over time of conduction and rhythm disorders in transthyretin wild-type transthyretin cardiac amyloidosis (ATTRwt) is scarce.                                                                                                                                                                                                             The baseline and follow-up ECG traces and Holter monitoring of patients treated with tafamidis from our prospectively-maintained database (NCT05444920) were reviewed. Changes between baseline and follow-up evaluations were tested for significance.                  We included 265 patients (Table). Follow-up evaluations were scheduled at 12 months. At baseline, 54(21%) patients had history or permanent (70[28%]) atrial fibrillation (AF). Forty-one (16%) had a cardiac implantable electronic device, plus 17(6%) undergoing implantation during follow-up. Median PR interval was 200(180-230)msec, with a trend toward prolongation at follow-up (p=0.055). QRS duration increased over time (100[90-122]vs120[90-140]msec, p=0.002) with longer QRS duration in 57% of patients at follow-up, together with prevalence of conduction disturbances (left anterior fascicular block, 52[23%]vs46[30%], p=0.008; right bundle branch block 31[14%]vs29[19%], p<0.001), with 16% and 12% of patients respectively, developing these abnormalities during follow-up. AF was common on Holter (29[25%]vs26[45%], p=0.039), with 21% of patients having the arrhythmia detected at follow-up. Ventricular ectopic beats were highly prevalent (~90%), although a burden >10% was found only in 2 patients at follow-up. Non-sustained ventricular tachycardia was found in 34%vs31% (p=0.804). Atrio-ventricular blocks were detected in 15%vs20% (p=0.754), and pauses >3 seconds from 4% up to 7% of patients at follow-up.                                                                                                                                                     Conduction and rhythm disorders are common in ATTRwt, with progression and worsening over time. Ageing and cardiovascular comorbidities might influence these findings. Larger prospective case-control studies will clarify the potential impact of tafamidis in modifying patients’ arrhythmic profiles.



**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.**
Giuseppe Damiano Sanna
_1. Amyloidosis Research and Treatment Center, Department of Molecular Medicine, Foundation IRCCS Policlinico San Matteo, Pavia (Italy)_
_2. Clinical and Interventional Cardiology, Sassari University Hospital, Sassari (Italy)_

**Main Body of the Abstract**
Data regarding evolution over time of conduction and rhythm disorders in transthyretin wild-type transthyretin cardiac amyloidosis (ATTRwt) is scarce.                                                                                                                                                                                                             The baseline and follow-up ECG traces and Holter monitoring of patients treated with tafamidis from our prospectively-maintained database (NCT05444920) were reviewed. Changes between baseline and follow-up evaluations were tested for significance.                  We included 265 patients (Table). Follow-up evaluations were scheduled at 12 months. At baseline, 54(21%) patients had history or permanent (70[28%]) atrial fibrillation (AF). Forty-one (16%) had a cardiac implantable electronic device, plus 17(6%) undergoing implantation during follow-up. Median PR interval was 200(180-230)msec, with a trend toward prolongation at follow-up (_p_=0.055). QRS duration increased over time (100[90-122]_vs_120[90-140]msec, _p=_0.002) with longer QRS duration in 57% of patients at follow-up, together with prevalence of conduction disturbances (left anterior fascicular block, 52[23%]_vs_46[30%], _p_=0.008; right bundle branch block 31[14%]_vs_29[19%], _p_<0.001), with 16% and 12% of patients respectively, developing these abnormalities during follow-up. AF was common on Holter (29[25%]_vs_26[45%], _p_=0.039), with 21% of patients having the arrhythmia detected at follow-up. Ventricular ectopic beats were highly prevalent (~90%), although a burden >10% was found only in 2 patients at follow-up. Non-sustained ventricular tachycardia was found in 34%_vs_31% (_p_=0.804). Atrio-ventricular blocks were detected in 15%_vs_20% (_p_=0.754), and pauses >3 seconds from 4% up to 7% of patients at follow-up.                                                                                                                                                     Conduction and rhythm disorders are common in ATTRwt, with progression and worsening over time. Ageing and cardiovascular comorbidities might influence these findings. Larger prospective case-control studies will clarify the potential impact of tafamidis in modifying patients’ arrhythmic profiles.



Prevalence and evolution over time of 12-lead ECG and Holter monitoring features in patients with wild-type transthyretin cardiac amyloidosis PB130 (#472)

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.