Original ArticleMetabolic activity of the left and right atria are differentially altered in patients with atrial fibrillation and LV dysfunction
Introduction
Atrial fibrillation (AF) is the most frequently encountered cardiac arrhythmia.1,2 It is associated with increased morbidity and mortality and is an independent risk factor for stroke.3 It has been shown that “atrial fibrillation begets atrial fibrillation”4 through a poorly understood process often referred to as “atrial remodeling”.5
A change in atrial metabolism during the arrhythmic state may play a role in promoting the AF substrate, due to increased atrial metabolic demand.6,7 Findings in animal models and human studies have suggested a link between altered metabolic activity, including altered glucose metabolism and this common arrhythmia.8, 9, 10, 11, 12, 13
A deeper comprehension of the pathophysiology and metabolic changes associated with AF may lead to potential targets for therapy. Although treatments to restore sinus rhythm such as cardioversion and catheter ablation have demonstrated success, they still have diminished effectiveness along with increased recurrence rates the longer a patient has been in AF.14,15
[18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging provides the ability to further investigate metabolic changes that may accompany atrial remodeling.16,17
There are limited imaging studies, mainly in cancer patient populations, evaluating atrial metabolic activity,18, 19, 20, 21 but none to our knowledge, using cardiac PET imaging to compare AF patients to a control population.
The aim of the present investigation was to quantitatively compare patterns of glucose uptake measured using FDG PET-CT imaging, in patients with versus without atrial fibrillation. We assessed a cohort of patients who also had LV dysfunction undergoing viability imaging. We hypothesized that patients in this cohort with persistent AF may have increased atrial FDG uptake compared to those without AF.
Section snippets
Patient Population
The study was a single center, retrospective analysis among patients from a registry database, with evidence of left-ventricular (LV) dysfunction (LVEF < 45%), history of coronary artery disease, and having undergone myocardial viability FDG PET-CT imaging between January 2010 and April 2015.The study was approved by the human research ethics board of the University of Ottawa Heart Institute.
Fifty-three consecutive FDG PET viability imaging patients were identified with some history of AF.
Baseline Demographics
The baseline characteristics of the study population (n = 72) are shown in Table 1. As per the pre-defined match criteria, both the AF group and noAF groups had equal composition of diabetes and female patients, with comparable age and LVEF. Not surprisingly, the AF group had a significantly higher proportion of patients with history of stroke or TIA than the noAF group. As expected, there was also a higher proportion of oral anticoagulation (OAC) with both Coumadin and DOAC in the AF group.
Discussion
In this study of patients with LV dysfunction, we demonstrated a significant increase in FDG uptake in the right atrial free wall among those with AF compared to those without AF. However, we did not find a difference in the left atrial free wall FDG uptake between these two groups. We also demonstrated a significant correlation between FDG uptake and right atrial volume. There was no such relationship between FDG uptake and left atrial volume. We demonstrated that when accounting for atrial
New Knowledge Gained
In patients with LV dysfunction from ischemic cardiomyopathy, there is a significant increase in FDG uptake in the right atrial free wall among those with persistent or permanent AF compared to those without AF. However, no difference in the left atrial free wall FDG uptake was found between these two groups. There is a significant correlation between RA FDG uptake and RA volume. There was no such relationship between FDG uptake and LA volume. When accounting for atrial volume, the presence of
Conclusion
Increased glucose uptake was observed in the right atrial free wall of patients with LV dysfunction from ischemic cardiomyopathy and with AF compared to those without AF. The presence of AF was a statistically significant predictor of higher RA FDG uptake, even after accounting for increased atrial volume. Further study is warranted to determine the temporal nature of these findings during AF. This may help to determine the full clinical significance of this observation and presents an
Acknowledgments
BWJC is the UOHI Goldfarb Chair in Cardiac Imaging. RSB is a Tier 1 Research Chair supported by the University of Ottawa and was a career investigator supported by the Heart and Stroke Foundation of Ontario.
Disclosures
BWJC receives research support from CV Diagnostix and educational support from TeraRecon Inc and has equity interest in GE. RdK has received research grant support and honoraria from Lantheus Medical Imaging, Jubilant DraxImage, and GE Healthcare. RdK receives royalty revenues from
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Cited by (0)
JNC thanks Erick Alexanderson, MD, and Isabel Carvajal-Juárez, MD, Instituto Nacional de Cardiología Ignacio Chávez, Mexico, for providing the Spanish abstract; Weihua Zhou, Ph.D., Michigan Technological University, Michigan, for providing the Chinese abstract; and Raymond Taillefer, MD, Hopital du Haut-Richelieu, Canada, for providing the French abstract.
The authors of this article have provided a PowerPoint file, available for download at SpringerLink, which summarizes the contents of the paper and is free for re-use at meetings and presentations. Search for the article DOI on SpringerLink.com.
The authors have also provided an audio summary of the article, which is available to download as ESM, or to listen to via the JNC/ASNC Podcast.
Robert A. deKemp and Rob S. B. Beanlands are co-senior authors.
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