CT Able to Detect Stenoses in Coronary Artery Bypass Grafts (CABGs)

A recent study set out to determine the accuracy of 16- and 64-section CT for assessment of coronary artery bypass grafts (CABGs).

The results have shown that multidetector ECG-gated 16-section and 64-section CT is accurate in evaluating coronary artery bypass grafts for both occlusion as well as significant stenosis (>50%).

The Study
A database search was performed for all articles that met the following criteria:

• used CT to evaluate stenosis (>50%) or occlusion of CABG; employed a 16- or 64-section CT scanner;
• tabulated cases in absolute numbers such that true-positive, true-negative, false-positive, and false-negative results could be gleaned;
• employed invasive coronary angiography as the reference standard.

Graft assessability including that of the distal anastomosis ranged from 78% to 100% (mean, 92.4%), 90% with 16-slice and 96% with 64-slice CT.

For occlusion or significant stenosis (>50%), the rates of sensitivity, specificity, positive predictive value, and negative predictive value of multidetector CT were 97.6%, 96.7%, 92.7%, and 98.9%, respectively.

The studies that included data for CABG occlusion investigation had a sensitivity of 99.3% and a specificity of 98.7% of multidetector CT for graft occlusion.

The studies that included data for CABG significant stenosis (>50%) had a sensitivity of 94.4% and a specificity of 98.0% of multidetector CT for significant graft stenosis.

Conclusions
16- and 64-section CT has a high accuracy for evaluating CABG.

Reviewer’s Comments

Multidetector ECG-gated 16-section and 64-section CT is accurate in evaluating coronary artery bypass grafts for both occlusion as well as significant stenosis (>50%).

The meta-analysis data indicate that multidetector CT is more accurate in evaluating CABG for significant stenosis than for evaluating the native coronary arteries for significant stenosis.

The authors note that this may be due to the greater diameter of, less calcification within, and relative fixed position of CABG compared with the native coronary arteries.

Author: Vineet R. Jain, MD

Reference:
Hamon M, Lepage O, et al. Diagnostic Performance of 16- and 64-Section Spiral CT for Coronary Artery Bypass Graft Assessment: Meta-Analysis. Radiology; 2008; 247 (June): 679-686