Radiology: MRI links pericardial fat with atherosclerotic plaque
Pericardial fat measured by MRI correlated more strongly with plaque eccentricity than body mass index (BMI) and waist circumference, according to a study published online Aug. 16 in Radiology. The relationship between pericardial fat and overall plaque burden was stronger for men than women in the study.
Pericardial fat has been implicated in atherosclerosis. In the early stages of atherosclerosis, plaques tend to be eccentric, with higher eccentricity indicating a greater disease extent. In addition, plaque eccentricity is related to plaque vulnerability and instability.
However, data about pericardial fat in asymptomatic individuals are limited, partially because the primary assessment method, intravascular ultrasound, is invasive.
While previous studies have looked at the relationship of pericardial fat to atherosclerosis in patients with severe coronary disease, this was the first study to determine the association of pericardial fat on the coronary artery plaque burden in asymptomatic individuals.
“The individuals in this study had no symptoms and were otherwise healthy,” said the study's senior author David A. Bluemke, MD, PhD, director of radiology and imaging sciences at the National Institutes of Health Clinical Care. “They did not have significant coronary artery narrowing. Yet, despite this, they had coronary plaque that could be detected by MRI.”
To determine the relationship between pericardial fat and atherosclerotic plaque in an asymptomatic cohort, the researchers leveraged a sub-cohort from the Multi-Ethnic Study of Atherosclerosis and enrolled 183 participants between October 2005 and February 2008.
The study included 89 women and 94 men with a mean age of 61 years. Participants underwent coronary artery wall MRI to measure coronary artery plaque eccentricity (ratio of maximal to minimal artery wall thickness). Subjects also underwent cardiac CT studies to measure pericardial fat volume, defined as epicardial fat within the visceral pericardium plus pericardial fat.
The researchers found that significantly more men than women had dyslipidemia and a non-zero coronary artery calcium score. Men also had higher pericardial fat volumes, waist circumference, blood glucose levels, diastolic blood pressure, calcium scores, carotid intima-to-media thickness and lower high-density lipoprotein.
Women, meanwhile, had significantly higher total cholesterol and C-reactive protein levels, according to the study's lead author Cuilian Miao, MD, from the department of radiology at Northwestern University Medical School in Chicago, and colleagues.
The researchers reviewed 203 coronary artery wall images in men and 184 in women, and found men had a significantly greater mean coronary artery wall thickness (2 mm vs. 1.9 mm) and mean maximal wall thickness.
Men’s pericardial fat volume positively correlated with MR-determined plaque eccentricity, explained Miao and colleagues. An increment of one standard deviation in pericardial fat volume translated into a 0.3 increase in plaque eccentricity in men. The correlation remained after adjusting for BMI and waist circumference.
In women, pericardial fat volume also positively correlated with plaque eccentricity. However, the relationship attenuated after adjusting for BMI and waist circumference.
“Our results in these asymptomatic individuals are consistent with findings in patients with advanced atherosclerotic disease—namely, that a large amount of pericardial fat is significantly associated with measures of atherosclerotic disease,” offered Miao et al.
The researchers acknowledged some limitations to the study, noting that it does not offer information about the origin of the correlation between pericardial fat and plaque burden, or why the relationship was more pronounced in men than in women.
Miao and colleagues emphasized that pericardial fat accumulation may be an indicator of greater risk for increased plaque burden, particularly in men.
Pericardial fat has been implicated in atherosclerosis. In the early stages of atherosclerosis, plaques tend to be eccentric, with higher eccentricity indicating a greater disease extent. In addition, plaque eccentricity is related to plaque vulnerability and instability.
However, data about pericardial fat in asymptomatic individuals are limited, partially because the primary assessment method, intravascular ultrasound, is invasive.
While previous studies have looked at the relationship of pericardial fat to atherosclerosis in patients with severe coronary disease, this was the first study to determine the association of pericardial fat on the coronary artery plaque burden in asymptomatic individuals.
“The individuals in this study had no symptoms and were otherwise healthy,” said the study's senior author David A. Bluemke, MD, PhD, director of radiology and imaging sciences at the National Institutes of Health Clinical Care. “They did not have significant coronary artery narrowing. Yet, despite this, they had coronary plaque that could be detected by MRI.”
To determine the relationship between pericardial fat and atherosclerotic plaque in an asymptomatic cohort, the researchers leveraged a sub-cohort from the Multi-Ethnic Study of Atherosclerosis and enrolled 183 participants between October 2005 and February 2008.
The study included 89 women and 94 men with a mean age of 61 years. Participants underwent coronary artery wall MRI to measure coronary artery plaque eccentricity (ratio of maximal to minimal artery wall thickness). Subjects also underwent cardiac CT studies to measure pericardial fat volume, defined as epicardial fat within the visceral pericardium plus pericardial fat.
The researchers found that significantly more men than women had dyslipidemia and a non-zero coronary artery calcium score. Men also had higher pericardial fat volumes, waist circumference, blood glucose levels, diastolic blood pressure, calcium scores, carotid intima-to-media thickness and lower high-density lipoprotein.
Women, meanwhile, had significantly higher total cholesterol and C-reactive protein levels, according to the study's lead author Cuilian Miao, MD, from the department of radiology at Northwestern University Medical School in Chicago, and colleagues.
The researchers reviewed 203 coronary artery wall images in men and 184 in women, and found men had a significantly greater mean coronary artery wall thickness (2 mm vs. 1.9 mm) and mean maximal wall thickness.
Men’s pericardial fat volume positively correlated with MR-determined plaque eccentricity, explained Miao and colleagues. An increment of one standard deviation in pericardial fat volume translated into a 0.3 increase in plaque eccentricity in men. The correlation remained after adjusting for BMI and waist circumference.
In women, pericardial fat volume also positively correlated with plaque eccentricity. However, the relationship attenuated after adjusting for BMI and waist circumference.
“Our results in these asymptomatic individuals are consistent with findings in patients with advanced atherosclerotic disease—namely, that a large amount of pericardial fat is significantly associated with measures of atherosclerotic disease,” offered Miao et al.
The researchers acknowledged some limitations to the study, noting that it does not offer information about the origin of the correlation between pericardial fat and plaque burden, or why the relationship was more pronounced in men than in women.
Miao and colleagues emphasized that pericardial fat accumulation may be an indicator of greater risk for increased plaque burden, particularly in men.