Wilk Benjamin, Lim Heeseung, Hicks Justin, Sullivan Rebecca, Thiessen Jonathan D, Kovacs Michael, Sykes Jane, Biernaski Heather, Duffett Stephen, Prato Frank S, Skanes Allan
Western University, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
Lawson Health Research Institute, London, Ontario, Canada.
JACC Clin Electrophysiol. 2025 Apr;11(4):735-748. doi: 10.1016/j.jacep.2025.02.012.
Atrial fibrillation is associated with abnormal synchronization of left atrial electrical activity and substantially increased risk of myocardial infarction, stroke and heart failure.
This study sought to investigate, in a canine model of atrial fibrosis, the relationship between left atrial sympathetic innervation (by C-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.
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.
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.
Mild-to-moderate LA interstitial fibrosis may be present before affecting LA voltage maps. PET may be promising for detecting early atrial fibrillation.
心房颤动与左心房电活动异常同步有关，且心肌梗死、中风和心力衰竭的风险大幅增加。
本研究旨在探讨在犬心房纤维化模型中，通过C-羟基麻黄碱正电子发射断层扫描（PET）测量的左心房交感神经支配、通过磁共振成像（MRI）测量的细胞外容积和通过电压标测测量的心内膜电压之间的关系，这些指标在体内测量，而左心房（LA）组织纤维化程度在死后通过组织学测量。
对9只成年雌性犬进行PET/MRI联合成像。然后给这些动物植入双腔起搏器，1周后，6只动物以220至240次/分钟的频率起搏5周，而另外3只进行假手术。再过1周后，再次对动物进行PET/MRI成像并进行电压标测。然后对动物实施安乐死，切除心脏，使用Masson三色染色法确定LA纤维化的程度和位置。
舒张末期容积和收缩末期容积增加，左心室和LA的交感神经支配（通过PET测量）增加，LA的间质纤维化增加，LV的细胞外容积增加。间质纤维化程度与双极电压、MRI或摄取分数率之间无显著相关性。间质纤维化与单极电压之间存在微弱但显著的负相关。延迟强化未能检测到LA间质纤维化。
轻度至中度LA间质纤维化可能在影响LA电压标测之前就已存在。PET在检测早期心房颤动方面可能很有前景。
