Correlates of Angiographic Changes and Coronary Events
Condition: Cardiovascular Diseases; Coronary Disease; Coronary Arteriosclerosis; Heart Diseases
MeSH terms: Cardiovascular Diseases; Heart Diseases; Coronary Disease; Coronary Artery Disease; Arteriosclerosis; Myocardial Ischemia
Study type: Observational

Summary: 
      To examine the appropriateness of angiographic and ultrasound endpoints as predictors of
      subsequent clinical coronary events. Follow-up data from the Cholesterol Lowering in
      Atherosclerosis Study (CLAS) were used.
    

Detailed description: 
      BACKGROUND:

      A multitude of coronary angiographic trials have been conducted using various endpoint
      measures based on repeated coronary angiograms. Relative to coronary event trials,
      angiographic trials require both a smaller sample size and reduced trial length. While such
      trials have assumed that angiographic endpoints are valid surrogate measures for clinical
      coronary events, this assumption has not been completely tested. Although several coronary
      angiographic endpoints are available for trial outcomes, no single method has been uniformly
      accepted as optimal. Because of this, the utility and validity of coronary angiographic
      progression for predicting future clinical coronary events remains unsettled.

      The recent advent of carotid ultrasonography to assess arterial intima-media thickness (IMT)
      offers the exciting potential for a noninvasive measure of atherosclerosis. Because of its
      noninvasiveness, carotid IMTallows the extension of anti-atherosclerotic trials to both
      asymptomatic and frail subjects, for whom coronary angiography might be medically unethical.
      Because there is currently only limited support for the association of carotid IMT with
      clinical events or coronary atherosclerosis, the validity of carotid IMT as a potential
      surrogate for either endpoint has not been established.

      The Cholesterol Lowering Atherosclerosis Study (CLAS) was a coronary angiographic trial
      testing the efficacy of colestipol-niacin therapy in 188 nonsmoking, 40-59 year old men with
      previous coronary artery bypass graft surgery. Coronary artery atherosclerosis change was
      evaluated both by human consensus panel and by quantitative coronary angiography (QCA). In
      addition, B-mode ultrasounds of the common carotid artery was conducted every six months to
      provide measures of carotid IMT. Since the competion of the two-year CLAS study, subjects
      have been followed for up to 12 years. This long term follow-up of the CLAS cohort permits
      examination of the appropriateness of angiographic and ultrasound arterial endpoints as
      predictors of subsequent clinical coronary events. Angiographic and ultrasound (carotid IMT)
      endpoints also allow for testing of the associations between these various serial measures of
      atherosclerotic progression.

      The results of these analyses will provide important information on the validity of these
      measures, which are in current use as trial endpoints, as surrogates for clinical coronary
      events.

      DESIGN NARRATIVE:

      The study used angiographic and ultrasound carotid intima medial thickness endpoints for
      testing the associations between these various serial measures of atherosclerotic progression
      and subsequent coronary heart disease.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        188 nonsmoking, 40-59 year old men with previous coronary artery bypass graft surgery