Related Experiment Video
Updated: May 9, 2025
Estimating Bilateral Atrial Function by Cardiovascular Magnetic Resonance Feature Tracking in Patients with Paroxysmal Atrial Fibrillation
Published on: July 20, 2022
Complexities of Atrial Fibrosis Imaging: Exploring Relationships Between Endocardial Voltage, Extracellular Volume,
Benjamin Wilk1, Heeseung Lim2, Justin Hicks1
1Western University, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
Background:
Atrial fibrillation is associated with abnormal synchronization of left atrial electrical activity and substantially increased risk of myocardial infarction, stroke and heart failure.
Objectives:
This study sought to investigate, in a canine model of atrial fibrosis, the relationship between left atrial sympathetic innervation (by 11C-hydroxyephedrine positron emission tomography [PET]), extracellular volume (by magnetic resonance imaging [MRI]) and endocardial voltage (by voltage mapping), measured in vivo with the extent of left atrial (LA) tissue fibrosis measured post mortem with histology.
Methods:
A total of 9 adult female canines were imaged with hybrid PET/MRI. The animals were then implanted with a dual chamber pacemaker, and 1 week later, 6 animals were paced at 220 to 240 beats/min for 5 weeks, whereas the other 3 had sham surgeries. After another week, the animals were again imaged with PET/MRI and had voltage maps taken. The animals were then euthanized, hearts were excised, and the extent and location of LA fibrosis was determined using Masson's trichrome stain.
Results:
End-diastolic volume and end-systolic volume increased, sympathetic innervation (measured with PET) increased in the left ventricle and LA, interstitial fibrosis increased in the LA, and extracellular volume increased in the LV. There was no significant correlation of the extent of interstitial fibrosis with bipolar voltage, MRI, or fractional uptake rate. A weak, but significant, negative correlation was found between interstitial fibrosis and unipolar voltage. Delayed enhancement failed to detect LA interstitial fibrosis.
Conclusions:
Mild-to-moderate LA interstitial fibrosis may be present before affecting LA voltage maps. PET may be promising for detecting early atrial fibrillation.
