Noninvasive Detection of Coronary Artery Bypass Graft Patency by Intravenous Electron Beam Computed Tomographic Angiography

Coronary artery bypass grafts assessment at one year by noninvasive multislice computed tomography and invasive coronary angiography

OBJECTIVE

: The aim of this study was to evaluate and compare the postoperative graft patency by multislice computed tomography (MSCT) and invasive coronary angiography (ICA) in patients with multivessel coronary artery bypass grafting at 1 year of surgery.

METHODS

: Patients (n = 114) who underwent isolated coronary artery bypass grafting at least 1 year (1.4 ± 0.4 years) previously were subjected to both 16-slice CT angiography with cardiac gating and ICA, and their results were evaluated and compared. All patients were receiving β-blockers; mean heart rate was 64 ± 6 beats/min.

RESULTS

: The mean age of the patients was 59.7 ± 8.5 years. There was a total of 338 grafts (113 internal mammary artery grafts, 8 radial artery grafts, and 217 saphenous venous grafts). On MSCT angiography, all the left internal mammary arteries were visualized with 3D reconstruction. All internal mammary arteries were found to be patent. Twenty-one grafts were occluded or stenosed (21/338, 6.25%). One occluded graft was on the anterior wall (1/20, 0.83%), 11 occluded grafts were on the lateral wall of the heart (11/128, 8.59%), and 9 occluded grafts were on the inferior wall of the heart (9/90, 10.0%); MSCT resulted in no false-positive diagnosis of stenosis (specificity, 100%). However, 2 grafts that were found to be patent on MSCT angiography were blocked on ICA (MSCT sensitivity, 96.3%).

CONCLUSIONS

: Postoperative assessment of coronary bypass grafts is possible with an excellent resolution by MSCT angiography. Patency of bypass grafts can be checked by MSCT angiography, and the assessment is comparable with ICA.

Noninvasive Assessment of Off-Pump Coronary Artery Bypass Surgery by 16-Channel Multidetector-Row Computed Tomography

BACKGROUND

Sixteen-channel multidetector-row computed tomography (MDCT), with higher spatial and temporal resolution, enables noninvasive visualization of images with reduced motion artifact and breath-holding time. We compared images of 16-channel MDCT and selective bypass graft angiography among patients who had off-pump coronary artery bypass graft surgery.

METHODS

The study, conducted from April 2003 to March 2004, involved 42 patients who underwent off-pump coronary artery bypass graft surgery. Samples yielded a total of 96 arterial grafts, 5 vein grafts. Sixteen-channel MDCT (LightSpeed Ultra 16; GE Healthcare, Milwaukee, Wisconsin) was performed on each patient using 500-ms or 600-ms rotation time, 0.625-mm slice thickness, and mean scanning time of approximately 24 seconds.

RESULTS

If several sequential anastomoses in one graft existed, each was calculated as a separate graft. Selective bypass graft angiography yielded a patency rate of 97% (155 of 160). Multidetector-row computed tomography enabled detection of 143 of 155 patent grafts and all 5 occluded grafts visualized by selective bypass graft angiography (100% sensitivity and 93% specificity for graft occlusion after exclusion of grafts not evaluated by MDCT). In 149 graft anastomoses of 143 patent grafts viewed by MDCT, 2 significant stenoses were detected by both selective bypass graft angiography and MDCT. Twelve distal anastomoses were not evaluated by MDCT because of metallic clip artifacts. Evaluation possible graft anastomoses were 92%. Sensitivity and specificity for significant stenosis after exclusion of graft anastomoses not evaluated by MDCT were 100% and 99%, respectively.

CONCLUSIONS

High-quality 16-channel MDCT images allowed detection of graft occlusion and significant stenosis of graft anastomosis after off-pump coronary artery bypass graft surgery, demonstrating an alternative tool less invasive than selective bypass graft angiography to assess grafts after surgery.

Coronary artery bypass graft imaging using ECG-gated multislice computed tomography: Comparison with catheter angiography

AIM

To compare the value of multislice computerized tomography (MSCT) in imaging coronary artery bypass grafts (CABGs) by direct quantitative comparison with standard invasive angiography.

METHODS

Using MSCT, 50 consecutive patients who had previously undergone CABG surgery and had recently undergone invasive angiography for recurrent angina pectoris, were studied further using MSCT after intravenous injection of non-ionic contrast agent; cardiac imaging was performed during a single breath-hold. Graft anatomy was quantified, using both quantitative coronary angiography (QCA) and MSCT, by different investigators blinded to each other. Reproducibility was quantified using the standard error of the measurement expressed as a percentage in log-transformed values (CV%) and intraclass correlation (ICC).

RESULTS

All 150 grafts were imaged using MSCT; only 4 patent grafts were not imaged using selective angiography. Good agreement was achieved between MSCT and QCA on assessment of proximal anastomoses (CV% 25.2, ICC 0.84), mid-vessel luminal diameter (CV% 15.5, ICC 0.91) and aneurysmal dilations (CV% 14.3). Reasonable agreement was reached on assessment of distal anastomoses (CV% 26.7, ICC 0.66) and categorization of distal run-off (ICC 0.73). Good agreement was observed for stenoses of over 50% luminal loss (CV% 8.7, ICC 0.97) but agreement on assessment of less severe lesions was poor (CV% 208.7, ICC 0.51).

CONCLUSION

This study demonstrates that CABGs can be quantitatively evaluated using MSCT, and that significant lesions present in all CABG segments can be reliably identified. Agreement between MSCT and QCA for lesions of less than 50% luminal loss was poor.