Increased pericardial fat volume measured from noncontrast CT predicts myocardial ischemia by SPECT.
OBJECTIVE
We evaluated the association between pericardial fat and myocardial ischemia for risk stratification.


BACKGROUND
Pericardial fat volume (PFV) and thoracic fat volume (TFV) measured from noncontrast computed tomography (CT) performed for calculating coronary calcium score (CCS) are associated with increased CCS and risk for major adverse cardiovascular events.


METHODS
From a cohort of 1,777 consecutive patients without previously known coronary artery disease (CAD) with noncontrast CT performed within 6 months of single photon emission computed tomography (SPECT), we compared 73 patients with ischemia by SPECT (cases) with 146 patients with normal SPECT (controls) matched by age, gender, CCS category, and symptoms and risk factors for CAD. TFV was automatically measured. Pericardial contours were manually defined within which fat voxels were automatically identified to compute PFV. Computer-assisted visual interpretation of SPECT was performed using standard 17-segment and 5-point score model; perfusion defect was quantified as summed stress score (SSS) and summed rest score (SRS). Ischemia was defined by: SSS - SRS ≥4. Independent relationships of PFV and TFV to ischemia were examined.


RESULTS
Cases had higher mean PFV (99.1 ± 42.9 cm(3) vs. 80.1 ± 31.8 cm(3), p = 0.0003) and TFV (196.1 ± 82.7 cm(3) vs. 160.8 ± 72.1 cm(3), p = 0.001) and higher frequencies of PFV >125 cm(3) (22% vs. 8%, p = 0.004) and TFV >200 cm(3) (40% vs. 19%, p = 0.001) than controls. After adjustment for CCS, PFV and TFV remained the strongest predictors of ischemia (odds ratio [OR]: 2.91, 95% confidence interval [CI]: 1.53 to 5.52, p = 0.001 for each doubling of PFV; OR: 2.64, 95% CI: 1.48 to 4.72, p = 0.001 for TFV). Receiver operating characteristic analysis showed that prediction of ischemia, as indicated by receiver-operator characteristic area under the curve, improved significantly when PFV or TFV was added to CCS (0.75 vs. 0.68, p = 0.04 for both).


CONCLUSIONS
Pericardial fat was significantly associated with myocardial ischemia in patients without known CAD and may help improve risk assessment.
Department of Imaging, Cedars-Sinai Medical Center and Cedars-Sinai Heart Institute, Los Angeles, California, USA.
Balaji
B
Tamarappoo
Damini
D
Dey
Haim
H
Shmilovich
Ryo
R
Nakazato
Heidi
H
Gransar
Victor Y
VY
Cheng
John D
JD
Friedman
Sean W
SW
Hayes
Louise E J
LE
Thomson
Piotr J
PJ
Slomka
Alan
A
Rozanski
Daniel S
DS
Berman
D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000368:Aged; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005080:Exercise Test; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology; D016017:Odds Ratio; D010496:Pericardium / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014665:Vasodilator Agents
D014665:Vasodilator Agents