Effects of Bariatric Surgery on Cardiac Ectopic Fat: Lesser Decrease in Epicardial Fat Compared to Visceral Fat Loss and No Change in Myocardial Triglyceride Content

Objectives: This study investigated the effect of bariatric surgery (BS)-induced weight loss on cardiac ectopic fat using 3T magnetic resonance imaging in morbid obesity.

Background: Heart disease is one of the leading causes of mortality and morbidity in obese patients. Deposition of cardiac ectopic fat has been related to increased heart risk. Whether sustained weight loss can modulate epicardial fat or myocardial fat is unknown.

Methods: Twenty-three morbidly obese patients underwent 1H-magnetic resonance spectroscopy to determine myocardial triglyceride content (MTGC), magnetic resonance imaging to assess epicardial fat volume (EFV), cardiac function, and computed tomography visceral abdominal fat (VAF) measurements at baseline and 6 months after BS.

Results: The BS reduced body mass index significantly, from 43.1±4.5 kg/m2 to 32.3±4.0 kg/m2, subcutaneous fat from 649±162 cm2 to 442±127 cm2, VAF from 190±83 cm2 to 107±44 cm2, and EFV from 137±37 ml to 98±25 ml (all p<0.0001). There was no significant change in MTGC: 1.03±0.2% versus 1.1±0.2% (p=0.85). A significant reduction in left ventricular mass (118±24 g vs. 101±18 g) and cardiac output (7.1±1.6 l/min vs. 5.4±1.0 l/min) was observed and was statistically associated with weight loss (p<0.05). The loss in EFV was limited (-27±11%) compared to VAF diminution (-40±19%). The EFV variation was not correlated with percentage of body mass index or VAF loss (p=0.007). The ratio of %EFV to %VAF loss decreased with sleep apnea syndrome (1.34±0.3 vs. 0.52±0.08, p<0.05).

Conclusions: Six-month BS modulates differently cardiac ectopic fat deposition, with a significant decrease in epicardial fat and no change in myocardial fat. Epicardial fat volume loss was limited in patients with sleep apnea. (Impact of Bariatric Surgery on Epicardial Adipose Tissue and on Myocardial Function; NCT01284816).