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Mechanisms of coronary microcirculatory dysfunction in patients with aortic stenosis and angiographically normal

Kim Rajappan1, Ornella E Rimoldi, David P Dutka

  • 1Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, London, UK.

Circulation
|January 30, 2002
PubMed

Insights

In severe aortic stenosis, coronary microcirculation is impaired, especially in the left ventricle's subendocardium. This dysfunction is linked to aortic valve area and pressure, not just heart muscle size.

Area of Science:

  • Cardiovascular Physiology
  • Medical Imaging
  • Biomedical Engineering

Background:

  • Left ventricular hypertrophy (LVH) in aortic stenosis (AS) is associated with coronary microcirculatory dysfunction.
  • Evidence for regional myocardial blood flow (MBF) abnormalities and their mechanisms in AS-induced LVH is limited.
  • This study aimed to quantify regional microcirculatory differences and identify contributing factors.

Observation:

  • Twenty patients with moderate to severe AS underwent echocardiography, cardiac MRI, and PET imaging.
  • Myocardial blood flow (MBF) and coronary vasodilator reserve (CVR) were measured in subendocardial and subepicardial regions at rest and during hyperemia.
  • In severe AS, the subendocardial to subepicardial MBF ratio decreased during hyperemia, and subendocardial CVR was significantly lower than subepicardial CVR.

Findings:

  • Subendocardial CVR was more impaired than subepicardial CVR in patients with LVH due to severe AS.
  • The severity of CVR impairment correlated with aortic valve area, hemodynamic load, and reduced diastolic perfusion time.
  • Left ventricular mass was not directly correlated with CVR impairment.

Implications:

  • Regional microcirculatory dysfunction, particularly in the subendocardium, is a key feature of severe AS with LVH.
  • Aortic valve severity and hemodynamic factors are primary drivers of coronary microcirculatory impairment, outweighing the role of myocyte hypertrophy alone.
  • These findings highlight the importance of assessing regional coronary microcirculation in managing patients with AS.
Abstract

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