title: Obesity is associated with lower coronary microvascular density.
abstract: BACKGROUND
  Obesity is associated with diastolic dysfunction, lower maximal myocardial blood flow, impaired myocardial metabolism and increased risk of heart failure. We examined the association between obesity, left ventricular filling pressure and myocardial structure.
  
  
  METHODS
  We performed histological analysis of non-ischemic myocardium from 57 patients (46 men and 11 women) undergoing coronary artery bypass graft surgery who did not have previous cardiac surgery, myocardial infarction, heart failure, atrial fibrillation or loop diuretic therapy.
  
  
  RESULTS
  Non-obese (body mass index, BMI, ≤ 30 kg/m(2), n=33) and obese patients (BMI >30 kg/m(2), n=24) did not differ with respect to myocardial total, interstitial or perivascular fibrosis, arteriolar dimensions, or cardiomyocyte width. Obese patients had lower capillary length density (1145 ± 239, mean ± SD, vs. 1371 ± 333 mm/mm(3), P=0.007) and higher diffusion radius (16.9 ± 1.5 vs. 15.6 ± 2.0 μm, P=0.012), in comparison with non-obese patients. However, the diffusion radius/cardiomyocyte width ratio of obese patients (0.73 ± 0.11 μm/μm) was not significantly different from that of non-obese patients (0.71 ± 0.11 μm/μm), suggesting that differences in cardiomyocyte width explained in part the differences in capillary length density and diffusion radius between non-obese and obese patients. Increased BMI was associated with increased pulmonary capillary wedge pressure (PCWP, P<0.0001), and lower capillary length density was associated with both increased BMI (P=0.043) and increased PCWP (P=0.016).
  
  
  CONCLUSIONS
  Obesity and its accompanying increase in left ventricular filling pressure were associated with lower coronary microvascular density, which may contribute to the lower maximal myocardial blood flow, impaired myocardial metabolism, diastolic dysfunction and higher risk of heart failure in obese individuals.
authors: St. Vincent's Institute of Medical Research, Fitzroy, Australia ; Department of Medicine, The University of Melbourne, St. Vincent's Health, Fitzroy, Australia.
authors: Duncan J
authors: DJ
authors: Campbell
authors: Jithendra B
authors: JB
authors: Somaratne
authors: David L
authors: DL
authors: Prior
authors: Michael
authors: M
authors: Yii
authors: James F
authors: JF
authors: Kenny
authors: Andrew E
authors: AE
authors: Newcomb
authors: Darren J
authors: DJ
authors: Kelly
authors: Mary Jane
authors: MJ
authors: Black
mesh_terms: D003326:Coronary Circulation; D003971:Diastole; D005260:Female; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D055806:Microvessels / Q000473:pathology* / Q000503:physiopathology*; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D011312:Pressure; D012306:Risk; D018487:Ventricular Dysfunction, Left / Q000150:complications