Obesity is associated with lower coronary microvascular density

PLoS One. 2013 Nov 29;8(11):e81798. doi: 10.1371/journal.pone.0081798. eCollection 2013.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Coronary Circulation
  • Diastole
  • Female
  • Heart Failure / complications
  • Humans
  • Male
  • Microvessels / pathology*
  • Microvessels / physiopathology*
  • Middle Aged
  • Obesity / complications
  • Obesity / pathology
  • Obesity / physiopathology*
  • Pressure
  • Risk
  • Ventricular Dysfunction, Left / complications

Grant support

This work was funded by grants from the National Health and Medical Research Council of Australia and from the National Heart Foundation of Australia. Duncan Campbell (Grant ID 395508) and Darren Kelly (Grant ID 566867) are recipients of Senior Research Fellowships from the National Health and Medical Research Council of Australia. St Vincent's Institute of Medical Research is supported in part by the Victorian Government’s Operational Infrastructure Support Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.