Exploration of Arrhythmia Burden in Cardiac Amyloidosis Using Implantable Loop Recorders: The EXCALIBUR Study

Area of Science:

• Cardiology
• Electrophysiology
• Cardiomyopathy Research

Background:

• Cardiac amyloidosis (CA) is a progressive infiltrative cardiomyopathy.
• It is associated with conduction disease and arrhythmias, but their full extent and relation to disease phenotype are unclear.

Purpose of the Study:

• To prospectively characterize the arrhythmic burden in CA using implantable loop recorders (ILRs).
• To explore associations between arrhythmia patterns, amyloid subtype, and disease characteristics.

Main Methods:

• Prospective, single-centre observational study of 110 treatment-naïve patients with transthyretin amyloid cardiomyopathy (ATTR-CM) or light-chain CA (AL-CA).
• Comprehensive phenotyping including cardiac magnetic resonance, followed by ILR implantation.

Main Results:

• 17.3% of patients experienced bradyarrhythmias requiring pacemakers, more common in ATTR-CM than AL-CA.
• Baseline conduction abnormalities and higher myocardial amyloid burden predicted bradyarrhythmic events.
• New atrial fibrillation (AF) occurred in 28.2%, more frequent in ATTR-CM, with higher amyloid burden increasing risk.
• Mortality was 19.1%; terminal rhythms differed between ATTR-CM and AL-CA.

Conclusions:

• Clinically significant arrhythmias are common and often asymptomatic in CA.
• Arrhythmic burden and patterns vary by amyloid subtype and correlate with disease phenotype and amyloid load.
• Findings offer insights into CA arrhythmogenesis, supporting further research for risk stratification and management.