Multislice computed tomography for the evaluation of coronary bypass grafts and native coronary arteries: comparison with traditional angiography

A systematic review and meta-analysis of multidetector computed tomography in the assessment of coronary artery bypass grafts

PURPOSE

The present meta-analysis aimed to compare the diagnostic accuracy of more recent computed tomography coronary angiography (CTCA) with invasive coronary angiography (ICA) in the assessment of graft patency after coronary artery bypass graft surgery (CABG).

MATERIAL AND METHODS

A systematic review was performed using nine electronic databases from their dates of inception to July 2015. Predefined inclusion criteria included studies reporting on comparative outcomes using ≥64 slice multidetector computed tomography (MDCT) and ICA. The primary endpoints included graft occlusion and significant graft stenosis ≥50%. Secondary analyses included the comparison of arterial versus venous graft conduits, and the use of different MDCT techniques.

RESULTS

Thirty-one studies were identified according to selection criteria, involving 1975 patients with 5364 assessed grafts. Combined assessment of stenosis and occlusion for all grafts demonstrated a sensitivity of 96.1% [95% confidence interval (CI) 94.3-97.4%] and specificity of 96.3% (95% CI 95.1-97.3%). CTCA assessment of venous grafts demonstrated higher sensitivity compared to arterial grafts, when testing for both occlusion and stenosis (97.6% vs 89.2%, p=0.004).

CONCLUSION

Results of this study demonstrated that CTCA had a relatively high pooled sensitivity, specificity and negative predictive value compared to ICA. However, patient baseline characteristics varied between studies, and the results should be interpreted with caution. Nonetheless, our results indicate that CTCA should be recognized as an accurate and non-invasive investigation for graft patency in symptomatic patients after CABG.

Computerized tomography may underestimate the patency of internal thoracic artery composite grafts

BACKGROUND

Multidetector-row computerized tomography (MDCT) has been regarded as useful for noninvasive assessment of the bypass grafts after coronary artery bypass grafting (CABG), but there have been few reports validating its accuracy in assessment of composite arterial graft patency.

METHODS

In 108 patients who underwent CABG with a Y-composite graft made of bilateral internal thoracic arteries (ITAs), early postoperative (mean interval, 4.9 months) MDCT findings were compared with the findings of subsequent conventional coronary angiography (19 patients, mean 4.7 months after initial MDCT) or later MDCT (89 patients, mean 31.0 months after surgery). A total of 248 grafts with 409 distal anastomoses (mean 3.8/patient) were assessed.

RESULTS

In the early MDCT, the left ITA was patent in 94.4%. The right ITA with multiple sequential anastomoses was completely patent in 73.8% and partially patent in 21.4%. Discrepancy of findings between early computed tomography (CT) and later imaging studies was found in 18 patients (16.7%). Fourteen (42.4%, 4 left and 10 right ITAs) among the 33 initially nonvisualized grafts showed improved patency in later MDCT or conventional angiogram. The positive predictive value of the early MDCT for ITA composite graft occlusion was calculated at 57.6% or lower, whereas the negative predictive value was 97.8% or higher.

CONCLUSIONS

For a composite graft made of bilateral ITAs, especially for those with multiple sequential anastomoses, MDCT may reflect only the functional patency and underestimate the actual anatomic patency.

Thrombelastographic haemostatic status and antiplatelet therapy after coronary artery bypass surgery (TEG-CABG trial): assessing and monitoring the antithrombotic effect of clopidogrel and aspirin versus aspirin alone in hypercoagulable patients: study protocol for a randomized controlled trial

Background

Hypercoagulability, assessed by the thrombelastography (TEG) assay, has in several observational studies been associated with an increased risk of post-procedural thromboembolic complications. We hypothesize that intensified antiplatelet therapy with clopidogrel and aspirin, as compared to aspirin alone, will improve saphenous vein graft patency in preoperatively TEG-Hypercoagulable coronary artery bypass surgery (CABG) patients and reduce their risk for thromboembolic complications and death postoperatively.

Methods/Design

This is a prospective randomized clinical trial, with an open-label design with blinded evaluation of graft patency. TEG-Hypercoagulability is defined as a TEG maximum amplitude above 69 mm. Two hundred and fifty TEG-Hypercoagulable patients will be randomized to either an interventional group receiving clopidogrel 75 mg daily for three months (after initial oral bolus of 300 mg) together with aspirin 75 mg or a control group receiving aspirin 75 mg daily alone. Monitoring of antiplatelet efficacy and on-treatment platelet reactivity to clopidogrel and aspirin will be conducted with Multiplate aggregometry. Graft patency will be assessed with Multislice computed tomography (MSCT) at three months after surgery.

Conclusions

The present trial is the first randomized clinical trial to evaluate whether TEG-Hypercoagulable CABG patients will benefit from intensified antiplatelet therapy after surgery. Monitoring of platelet inhibition from instituted antithrombotic therapy will elucidate platelet resistance patterns after CABG surgery. The results could be helpful in redefining how clinicians can evaluate patients preoperatively for their postoperative thromboembolic risk and tailor individualized postoperative antiplatelet therapy.

Trial registration

Clinicaltrials.gov Identifier NCT01046942

Diagnostic performance of 320-slice multidetector computed tomography coronary angiography in patients after coronary artery bypass grafting

Objectives

To evaluate the diagnostic performance of 320-slice computed tomography coronary angiography (CTA) in the evaluation of patients with prior coronary artery bypass grafting (CABG). Invasive coronary angiography (ICA) served as the standard of reference, using a quantitative approach.

Methods

CTA studies were performed using CT equipment with 320 detector-rows, each 0.5 mm wide, and a gantry rotation time of 0.35 s. All grafts, recipient and nongrafted vessels were deemed interpretable or uninterpretable. The presence of significant (≥50%) stenosis and occlusion were determined on vessel and patient basis. Results were compared to ICA using quantitative coronary angiography.

Results

A total of 40 patients (28 men, 76 ± 15 years), with 89 grafts, were included in the study. On a graft analysis, the sensitivity, specificity, positive and negative predictive values in the evaluation of significant stenosis were 96%, 92%, 83% and 98% respectively. The diagnostic accuracy for the assessment of recipient and nongrafted vessels was 89% and 80%, respectively. The diagnostic accuracy for the assessment of graft, recipient and nongrafted vessel occlusion was 96%, 92% and 100%, respectively.

Conclusions

320-slice CTA allows accurate non-invasive assessment of significant graft, recipient vessel and nongrafted vessel stenosis in patients with prior CABG.

Diagnostic accuracy of 64-slice CT in evaluating coronary artery bypass grafts and of the native coronary arteries

PURPOSE

Our aim was to evaluate the accuracy, sensitivity and specificity of 64-slice multidetector computed tomography (MDCT) in the assessment of occlusions and stenoses of arterial and venous bypass grafts and disease progression in the native vessels distal to the graft, and to compare the results with those of conventional coronary angiography.

MATERIALS AND METHODS

We enrolled 78 individuals (45 men, 33 women; mean age 59) and evaluated 213 bypass grafts using a 64-slice MDCT scanner. All patients underwent conventional coronary angiography with a mean time interval between the two examinations of 2 days.

RESULTS

One patient was excluded due to arrhythmia during the examination. The 212 bypass grafts in the remaining 77 patients (98.7%) consisted of 115 (54%) venous grafts and 97 (46%) arterial grafts. In the 115 venous grafts, MDCT showed a sensitivity, specificity and accuracy of 100% in evaluating occluded grafts and a sensitivity of 94.4%, specificity of 98.4% and accuracy of 96.9% in evaluating significant stenoses. In evaluating occluded arterial grafts, sensitivity was 83.3%, specificity 100% and accuracy 98.9%, whereas in evaluating stenoses of arterial grafts, sensitivity was 100%, specificity 97.7% and accuracy 98%.

CONCLUSIONS

Sensitivity, specificity and accuracy in evaluating native coronary vessels distal to the graft allow for a complete assessment of the surgical and native circulation. The examination appears therefore to be exhaustive in ruling out or confirming the presence of diseased vessels in the postoperative follow-up.