Have an account? Please log in.
Text size: Small font Default font Larger font
.
Radiology Daily
Radiology Daily PracticalReviews.com Radiology Daily

Clinical Risk for Atherosclerosis Does Not Correlate With Coronary CT Angiography

May 8, 2009
Written by: , Filed in: Cardiac Imaging
  • Comments
.

A recent study was conducted to evaluate how the Framingham risk estimates and the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATP III) core risk categories correlate with atherosclerotic plaque burden as assessed by coronary CT angiography (CTA).

The study, published in AJR, indicates that traditional clinical determination of risk for coronary artery disease core risk categories do not correlate with atherosclerotic plaque burden as seen on coronary CT angiography in an individual patient.

The Study
1653 outpatients underwent CTA for clinical indication. Patients with a history of coronary artery disease (CAD) were excluded.

Methodology
Clinical data were obtained, and using this information, a Framingham risk estimate, which is the percentage risk of CAD occuring within 10 years, was calculated. NCEP core risk categories were also determined.

All CTAs were performed with a 64-slice multi-detector CT scanner. Images were evaluated using maximum-intensity-projection and curved reformat techniques on a 3-dimensional workstation. The amount of plaque seen in a given patient was evaluated using 4 methods:

  1. Segment plaque score – Each coronary segment had the amount of plaque within it characterized as none, mild, moderate, or heavy and was assigned a score.
  2. Segment stenosis score – Each segment had the degree of stenosis within it characterized and assigned a score.
  3. Segment involvement score – Each segment was characterized as either having plaque or not and was assigned a score.
  4. Modified Duke prognostic index – An index previously derived from invasive angiography, which takes into account the degree of stenosis in a segment and lesions carrying an increasing risk of a coronary event, are defined.

Cardiac CTA: What You Need to Know
 
 University of California San Francisco, Department of Radiology
 Course Director: Gautham P. Reddy, MD, MPH

 
  Coronary artery disease is the leading cause of morbidity and mortality in industrialized countries. With the advent of 64-detector CT scanners, CT has become an essential tool for evaluation of the heart and great vessels, and is a promising technique for assessment of the coronary arteries.
 
  Click here to read more or order:
  Cardiac CTA: What You Need to Know

The Results
31% of men and 46% of women had no atherosclerotic plaque on CTA.

Of patients, 11.6% had only noncalcified plaque.

The median Framingham 10-year risk was 8% for men and 2% for women.

The correlation of CTA plaque score with the Framingham 10-year risk estimates was modest
Spearman’s rho, 0.49 to 0.55.

There was weak agreement between NCEP core risk categories and defined atherosclerotic plaque categories.

The proportion of raw agreement, p0, was less than half for all comparisons of NCEP risk categories to plaque score categories.

Of patients who had moderate or high plaque burden using the segment plaque score, 55% were in matching moderately high and high-risk NCEP categories.

Of patients who had no plaque on CTA, 11% were in moderately high and high-risk NCEP categories. Cohen’s range was 0.18 to 0.20.

Of patients, 21% would have their seeming need for cholesterol-lowering statins changed using the coronary CTA plaque burden in place of the NCEP scheme. Also, 26% of patients on statins had no atherosclerotic plaque on CTA.

Conclusions
The traditional clinical determination of risk for coronary artery disease core risk categories do not correlate with atherosclerotic plaque burden as seen on coronary CT angiography in an individual patient.

The Framingham and NCEP core risk categories do not equate with the amount of atherosclerotic plaque as seen by CTA in individual patients.

Reviewer’s Comments

The authors demonstrate that coronary CTA can significantly alter clinical decisions regarding cholesterol-lowering statin use in an individual patient.

Author: Vineet R. Jain, MD

Reference:
Traditional Clinical Risk Assessment Tools Do Not Accurately Predict Coronary Atherosclerotic Plaque Burden: A CT Angiography Study.

Johnson KM, Dowe DA, Brink JA: AJR; 2009;192 (January): 235-243

Cardiac CTA: What You Need to Know
 
 University of California San Francisco, Department of Radiology
 Course Director: Gautham P. Reddy, MD, MPH

 
  Coronary artery disease is the leading cause of morbidity and mortality in industrialized countries. With the advent of 64-detector CT scanners, CT has become an essential tool for evaluation of the heart and great vessels, and is a promising technique for assessment of the coronary arteries.
 
  Click here to read more or order:
  Cardiac CTA: What You Need to Know
.
  • Comments
.

Would you like to keep current with radiological news and information?

Post Your Comments and Responses

Comments are closed.