Infiltrated atrial fat characterizes underlying atrial fibrillation substrate in patients at risk as defined by the ARIC atrial fibrillation risk score.
BACKGROUND
It is known that expanded epicardial fat is associated with atrial fibrillation (AF). However, infiltrated intraatrial fat has not been previously quantified in individuals at risk as determined by the ARIC AF risk score.


METHODS
Patients in sinus rhythm (N=90, age 57 ± 10 years; 55 men [63.2%]), in 3 groups at risk of AF as determined by the ARIC AF risk score [low (≤ 11 points; n=15), moderate (12-18 points; n=40), high (≥ 19 points; n=23) risk of AF], and paroxysmal AF (n=12) underwent cardiac magnetic resonance study. Intraatrial and epicardial fat was analyzed with a Dark-blood DIR-prepared Fat-Water-separated sequence in the horizontal longitudinal axis. OsiriX DICOM viewer (Geneva, Switzerland) was used to quantify the intraatrial fat area. Width of the cephalad portion of the interatrial septum was measured at the level of the fossa ovalis.


RESULTS
Intraatrial fat monotonically increased with growing AF risk in study groups (low AF risk 16 ± 4 vs. moderate AF risk 32 ± 18 vs. high AF risk 81 ± 83 mm(2); ANOVA P=0.012). Log-transformed intraatrial fat predicted ARIC AF risk score in multivariate ordered probit regression after adjustment for sex, race, left and right atrial area indices, and body mass index (β-coefficient 0.50 [95% CI 0.03-0.97]; P=0.037), whereas epicardial fat did not. Interatrial septum width showed similar association (3.0 ± 1.4 vs. 5.0 ± 1.8 vs. 7.1 ± 2.7 mm; ANOVA P<0.001; adjusted β-coefficient 2.80 [95% CI 1.19-4.41]; P=0.001).


CONCLUSIONS
Infiltrated intraatrial fat characterizes evolving substrate in individuals at risk of AF.
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States. Electronic address: lteresh1@jhmi.edu.
Larisa G
LG
Tereshchenko
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Patricia
P
Rizzi
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Nathan
N
Mewton
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Gustavo Jardim
GJ
Volpe
Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, United States.
Sindhoora
S
Murthy
Food and Drug Administration, Silver Spring, MD, United States.
David G
DG
Strauss
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Chia Y
CY
Liu
Hospital of the University of Pennsylvania, Philadelphia, PA, United States.
Francis E
FE
Marchlinski
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Peter
P
Spooner
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Ronald D
RD
Berger
National Institutes of Health, National Heart, Lung, and Blood Institute, Bethesda, MD, United States.
Peter
P
Kellman
The Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Joao A C
JA
Lima
D000273:Adipose Tissue / Q000473:pathology*; D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000473:pathology*; D054087:Atrial Septum / Q000473:pathology; D057791:Cardiac Imaging Techniques; D005260:Female; D006325:Heart Atria / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000473:pathology*; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors
Atrial fibrillation; Cardiac magnetic resonance; Intraatrial infiltrated fat; Risk score