Which type of amyloidosis is associated with ectopic arrhythmias?

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Last updated: September 22, 2026 • View editorial policy

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All Types of Cardiac Amyloidosis Are Associated with Arrhythmias, But Atrial Arrhythmias Predominate

All forms of cardiac amyloidosis that involve the heart are associated with ectopic arrhythmias, with atrial tachyarrhythmias (particularly atrial fibrillation) being the most common, followed by conduction system disease and ventricular arrhythmias. 1

Arrhythmia Patterns by Amyloid Type

Types with Cardiac Involvement and Arrhythmias:

Primary/Light Chain (AL) Amyloidosis:

  • Cardiac involvement in up to 50% of cases 1
  • Atrial fibrillation occurs in 23-55% of patients 2
  • Ventricular arrhythmias are more common than in ATTR due to direct light-chain cardiotoxicity 3
  • Conduction abnormalities including AV blocks 1

Transthyretin (ATTR) Amyloidosis (both hereditary and senile/wild-type):

  • Atrial fibrillation is the most frequent arrhythmia, occurring in up to 70% of ATTR patients 2
  • Bradyarrhythmias requiring pacemaker occur in 23.8% of ATTR-CM patients 4
  • More prevalent conduction system disease than AL 3
  • Common cardiac involvement, especially in senile/wild-type form 1

Isolated Atrial Amyloidosis:

  • Limited to heart, specifically atrial tissue 1
  • Would theoretically cause atrial arrhythmias given its localization

Types with Minimal/No Cardiac Involvement:

Reactive (AA) Amyloidosis:

  • Cardiac involvement <10% 1
  • Arrhythmias uncommon

Dialysis-Related Amyloidosis:

  • Cardiac involvement unknown/minimal 1

Mechanistic Understanding

The arrhythmogenesis occurs through multiple pathways 1:

  1. Direct infiltration of conduction tissue causing AV blocks and bradyarrhythmias
  2. Amyloid deposition in atrial walls causing atrial tachyarrhythmias
  3. Atrial dilation from elevated filling pressures (restrictive physiology) promoting atrial fibrillation
  4. Direct myocyte toxicity (especially in AL) causing ventricular arrhythmias

Recent Prospective Data

The EXCALIBUR study 4 using implantable loop recorders in 110 treatment-naïve patients revealed:

  • Bradyarrhythmias with Class I pacemaker indication: 17.3% overall (23.8% ATTR vs 8.5% AL)
  • New atrial fibrillation: 28.2% of those without prior AF (50% ATTR vs 12.2% AL)
  • Higher myocardial amyloid burden (measured by ECV) directly correlates with increased arrhythmic risk

Critical Clinical Pitfall

The terminal cardiac rhythm differs dramatically by subtype 4:

  • ATTR patients uniformly die from pulseless electrical activity (PEA)
  • AL patients die from PEA in 82% but have ventricular arrhythmias in 18%

This finding undermines the rationale for prophylactic ICD therapy in ATTR amyloidosis, as most deaths are not from shockable rhythms 3.

Key Electrocardiographic Features

All cardiac amyloidosis types share common ECG abnormalities 1, 5:

  • Low QRS voltage in limb leads despite ventricular wall thickening (≈50% of patients)
  • Pseudoinfarct pattern in precordial leads
  • Atrial fibrillation
  • AV conduction abnormalities

References

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