**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.**
Belen Peiro-Aventin
Department of Cardiology, Puerta de Hierro University Hospital of Majadahonda, Majadahonda, Spain

**Main Body of the Abstract**
Background: Clinical outcomes of ATTR-CM patients with pacemaker and left ventricular dysfunction who undergo cardiac resynchronization therapy (CRT) or left bundle branch pacing (LBBP) upgrade is unsettled.  We sought to describe the clinical evolution of ATTR-CM patients with left ventricular systolic dysfunction and pacemaker who underwent implantation of CRT/LBBP devices.
Methods: We retrospectively analyzed characteristics and clinical evolution of patients who underwent upgrade to CRT/LBBP at a single amyloid centre in Madrid, Spain.
Results: From December 2008 to January 2024, 12 patients with ATTR-CM [77.4±5 years, 100% male, 92% ATTRwt, LVEF 38% (range: 26-42%), 11 NYHA II/III] underwent upgrade from a conventional pacemaker (11 cases) or an ICD (1 case) to CRT (9 subjects) or LBBP (3 subjects). Ten patients have completed one year follow-up (1 died and 1 has been under follow-up for 1 month). At 1 year, QRS duration was reduced [168 (160-180) to 157 (150-160) ms; p=0.03] and LVEF remained stable [35% (22-44%) to 37% (30-43%); p=0.62]. No significant changes were observed in NtproBNP or diuretic dose. Five out of the 8 patients in NYHA class III improved to NYHA II. Over a median follow-up of 4 years (IQR 2.8-5.5), no device-related complications have occurred, 3 individuals have been hospitalized for heart failure, and 3 patients have died (3, 16 and 16 months after the upgrade).
Conclusions: CRT/LBBP upgrade resulted in improvement of NYHA class and stability of biomarkers and LVEF in a small series of ATTR-CM patients with systolic disfunction and a pacemaker.



**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.**
Belen Peiro-Aventin
Department of Cardiology, Puerta de Hierro University Hospital of Majadahonda, Majadahonda, Spain

**Main Body of the Abstract**
**Background**: Clinical outcomes of ATTR-CM patients with pacemaker and left ventricular dysfunction who undergo cardiac resynchronization therapy (CRT) or left bundle branch pacing (LBBP) upgrade is unsettled.  We sought to describe the clinical evolution of ATTR-CM patients with left ventricular systolic dysfunction and pacemaker who underwent implantation of CRT/LBBP devices.
**Methods**: We retrospectively analyzed characteristics and clinical evolution of patients who underwent upgrade to CRT/LBBP at a single amyloid centre in Madrid, Spain.
**Results**: From December 2008 to January 2024, 12 patients with ATTR-CM [77.4±5 years, 100% male, 92% ATTRwt, LVEF 38% (range: 26-42%), 11 NYHA II/III] underwent upgrade from a conventional pacemaker (11 cases) or an ICD (1 case) to CRT (9 subjects) or LBBP (3 subjects). Ten patients have completed one year follow-up (1 died and 1 has been under follow-up for 1 month). At 1 year, QRS duration was reduced [168 (160-180) to 157 (150-160) ms; p=0.03] and LVEF remained stable [35% (22-44%) to 37% (30-43%); p=0.62]. No significant changes were observed in NtproBNP or diuretic dose. Five out of the 8 patients in NYHA class III improved to NYHA II. Over a median follow-up of 4 years (IQR 2.8-5.5), no device-related complications have occurred, 3 individuals have been hospitalized for heart failure, and 3 patients have died (3, 16 and 16 months after the upgrade).
**Conclusions**: CRT/LBBP upgrade resulted in improvement of NYHA class and stability of biomarkers and LVEF in a small series of ATTR-CM patients with systolic disfunction and a pacemaker.



Impact of upgrading to cardiac resynchronization therapy or left bundle branch pacing in patients with ATTR cardiomyopathy PC67 (#389)

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.