Prevalence of American Heart Association type VI carotid atherosclerotic lesions identified by magnetic resonance imaging for different levels of stenosis as measured by duplex ultrasound

J Am Coll Cardiol. 2008 Mar 11;51(10):1014-21. doi: 10.1016/j.jacc.2007.10.054.


Objectives: Via magnetic resonance imaging (MRI), we sought to determine the prevalence of atherosclerotic American Heart Association type VI lesions (AHA-LT6) (lesions with luminal surface defect, hemorrhage/thrombus, or calcified nodule) in carotid arteries that represented all categories of stenosis as measured by duplex ultrasound.

Background: Arterial stenosis alone has been shown to be a poor predictor of cardiovascular events. Autopsy studies suggest that features associated with AHA-LT6 lesions, rather than the degree of luminal narrowing, characterize the high-risk plaque.

Methods: A total of 192 subjects underwent bilateral carotid artery magnetic resonance imaging (MRI) scans at 1.5T after evaluation with ultrasound to determine stenosis. After excluding arteries with a previous endarterectomy, poor image quality, or missing ultrasound data, there were 175 patients with 260 arteries available for analysis. The AHA lesion type was determined by the consensus opinion of 2 experienced carotid MRI reviewers.

Results: In total, 96 of 260 (37.0%) arteries had >or=1 location with AHA-LT6. Of the arteries with AHA-LT6, 84.4% had hemorrhage, 45.8% had a ruptured fibrous cap, and 14.6% showed other type of complications. Prevalence of AHA-LT6 was an increasing sequence of 8.1% in the 37 arteries with 1% to 15% stenosis, 21.7% in the 60 arteries with 16% to 49% stenosis, 36.8% in the 114 arteries with 50% to 79% stenosis, and 77.6% in the 49 arteries with 80% to 99% stenosis.

Conclusions: Complicated AHA-LT6 are frequently found in arteries with <or=50% stenosis. These findings indicate that complex lesions develop in a substantial number of arteries in the absence of high-grade stenosis. Ongoing prospective studies will determine the predictive value of vulnerable plaque features, as visualized by MRI, for risk of subsequent ischemic events.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Atherosclerosis / diagnosis*
  • Atherosclerosis / epidemiology
  • Carotid Artery Diseases / complications
  • Carotid Artery Diseases / diagnosis*
  • Carotid Artery Diseases / epidemiology
  • Carotid Stenosis / diagnostic imaging
  • Cross-Sectional Studies
  • Female
  • Hemorrhage / etiology
  • Humans
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Prevalence
  • Risk Factors
  • Ultrasonography, Doppler, Duplex
  • Ultrasonography, Interventional