Introduction:
The role of epicardial adipose tissue (EAT) in the development and vulnerability of coronary artery atherosclerosis has been the focus of extensive research for the past several years. EAT is visceral fat that surrounds the coronary arteries and it consists of beige adipose tissue that is functionally similar to brown adipose tissue and has a higher computed tomography (CT) attenuation than subcutaneous white adipose tissue. Given the brown-like composition of EAT, its attenuation may be affected by several factors including seasonal temperature variations and clinical factors.
Hypothesis:
We investigated the effect of season on EAT attenuation and additional clinical factors that may influence attenuation measurements.
Methods:
Single center, retrospective study of 597 cardiac CT exams performed for coronary artery calcium (CAC) scoring obtained on a single CT scanner during winter and summer months. Summer was defined as June, July, and August. Winter was defined as December, January, and February. EAT attenuation in Hounsfield units (HU) was measured in a region of interest near the right coronary artery ostium. Subcutaneous adipose tissue (SCAD) attenuation was measured in the thoracic subcutaneous tissue. Patients’ demographic and clinical characteristics were obtained by questionnaire and chart review.
Results:
The clinical and demographic characteristics of patients scanned during the summer (N=253) and the winter (N=344) months were similar. One third of patients were women, one quarter used statins and anti-hypertensive drugs each and 30% had a BMI>30. There was a significantly lower EAT attenuation measured during the summer than the winter months (-98.17±6.94 HUs vs -95.64±7.99 HUs; P<0.001). Additionally, gender, obesity, treatment with statins and anti-hypertensive agents significantly modulated the seasonal variation in EAT attenuation. SCAD attenuation was not affected by season or any other factor.
Conclusions:
Our study shows that the measurement of EAT attenuation is complex and is likely affected by season, demographics and clinical factors. Attempts to use EAT attenuation as a biomarker for risk of cardiovascular events should take these potential confounders into consideration.
EPICARDIAL ADIPOSE TISSUE VOLUME AND CORONARY ARTERY CALCIUM TO PREDICT MYOCARDIAL ISCHEMIA ON POSITRON EMISSION TOMOGRAPHY-COMPUTED TOMOGRAPHY STUDIES
