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

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.

A systematic review of radiation dose associated with different generations of multidetector CT coronary angiography

The purpose of this paper is to perform a systematic review on radiation dose reduction in coronary computed tomography (CT) angiography that is done using different generations of multidetector CT (MDCT) scanners ranging from four-slice to 320-slice CTs, and have different dose-saving techniques. The method followed was to search for references on coronary CT angiography (CTA) that had been published in English between 1998 and February 2011. The effective radiation dose reported in each study based on different generations of MDCT scanners was analysed and compared between the types of scanners, gender, exposure factors and scanning protocols. Sixty-six studies were eligible for inclusion in this analysis. The mean effective dose (ED) for MDCT angiography with retrospective electrocardiogram (ECG) gating without use of any dose-saving protocol was 6.0 ± 2.8, 10.4 ± 4.90 and 11.8 ± 5.9 mSv for four-slice, 16-slice and 64-slice CTs, respectively. More dose-saving strategies were applied in recent CT generations including prospective ECG-gating protocols, application of lower tube voltage and tube current modulation to achieve a noteworthy dose reduction. Prospective ECG-gating protocol was increasingly used in 64, 125, 256 and 320 slices with corresponding ED of 4.1 ± 1.7, 3.6 ± 0.4, 3.0 ± 1.9 and 7.6 ± 1.6 mSv, respectively. Lower tube voltage and tube current modulation were widely applied in 64-slice CT and resulted in significant dose reduction (P < 0.05). This analysis has shown that dose-saving strategies can substantially reduce the radiation dose in CT coronary angiography. The fact that more and more clinicians are opting for dose-saving strategies in CT coronary angiography indicates an increased awareness of risks associated with high radiation doses among them.

Noninvasive evaluation of coronary artery bypass grafts with 16-slice multidetector computed tomography

BACKGROUND

The aim of this study was to investigate the diagnostic accuracy of 16-slice multislice, multidetector computed tomography (MDCT) angiography for the evaluation of grafts in patients with coronary artery bypass grafting (CABG).

METHODS

Fifty-eight consecutive patients with CABG who underwent both MDCT and conventional invasive coronary angiography were included. The median time interval between the 2 procedures was 10 days (range, 1-32 days). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MDCT for the detection of occluded grafts were calculated. The accuracy of MDCT angiography for detecting significant stenoses in patent grafts and the evaluability of proximal and distal anastomoses were also investigated.

RESULTS

Optimal diagnostic images could not be obtained for only 3 (2%) of 153 grafts. Evaluation of the remaining 150 grafts revealed values for sensitivity, specificity, PPV, NPV, and diagnostic accuracy of the MDCT angiography procedure for the diagnosis of occluded grafts of 87%, 97%, 94%, 93%, and 92%, respectively. All of the proximal anastomoses were optimally visualized. In 4 (8%) of 50 patent arterial grafts, however, the distal anastomotic region could not be evaluated because of motion and surgical-clip artifacts. The accuracy of MDCT angiography for the detection of significant stenotic lesions was relatively low (the sensitivity, specificity, PPV, and NPV were 67%, 98%, 50%, and 99%, respectively). The number of significant lesions was insufficient to reach a reliable conclusion, however.

CONCLUSION

Our study showed that MDCT angiography with 16-slice systems has acceptable diagnostic performance for the evaluation of coronary artery bypass graft patency.

Non-invasive evaluation of internal thoracic artery anastomosed to the left anterior descending artery with 320-detector row computed tomography and adenosine thallium-201 myocardial perfusion scintigraphy

PURPOSE

We evaluated the relationship between internal thoracic artery (ITA) stenosis anastomosed to the left anterior descending artery (LAD) and the degree of LAD stenosis using 320-detector row computed tomography (320-ADCT) and adenosine thallium-201 myocardial perfusion scintigraphy (Tl-201-MPS).

METHODS

We included 101 patients who underwent coronary artery bypass grafting (CABG) using ITA grafts; 320-ADCT and adenosine Tl-201-MPS were performed 2-3 months after CABG. Clinical parameters, degree of LAD stenosis, and regional myocardial ischemia of the LAD territory were compared between patients without ITA stenosis (Group A) and with ITA stenosis (Group B).

RESULTS

Thirty patients (30%) had ≤75% LAD stenosis, and 9 patients (30%) showed significant ITA stenosis. Regional ischemia was noted in 23 patients (23%). There were no differences in clinical parameters between the 2 groups. Twenty-two patients (24%) in Group A and 8 patients (89%) in Group B had ≤75% LAD stenosis (P <0.002). No Group B patients had regional myocardial ischemia of the LAD territory.

CONCLUSION

We concluded that ≤75% LAD stenosis significantly influences ITA stenosis, without associated regional myocardial ischemia of the LAD territory. Non-invasive 320-ADCT and adenosine Tl-201-MPS for ITA evaluation may be useful for long-term follow-up of patients after CABG.

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.

Post-CABG coronary CT angiography: radiation dose and graft image quality in retrospective versus prospective ECG gating

RATIONALE AND OBJECTIVES

The aim of this study was to compare effective radiation doses between prospective and retrospective electrocardiographic gating during coronary computed tomographic angiography for coronary artery bypass grafting evaluation.

MATERIALS AND METHODS

Fifty consecutive coronary computed tomographic angiographic exams for coronary artery bypass grafting evaluation, 25 prospectively gated and 25 retrospectively gated, were reviewed from January 8, 2008, to June 16, 2009. Body mass index and image quality were also compared between the two groups. To minimize the potential bias introduced by differences in torso length, the effective radiation dose from each exam was measured and normalized to a 24-cm z-axis scan length for all patients. Pooled t tests were used to compare the prospectively and retrospectively gated groups.

RESULTS

The average effective doses delivered in the retrospective and prospective groups were 40.8 mSv (standard error [SE], 1.8 mSv) and 8.6 mSv (SE, 0.7 mSv), respectively. When normalized to the average z-axis scan length of 24 cm, the effective dose in the retrospective group, 38.4 mSv (SE, 1.3 mSv), was still >4 times greater than that in the prospective group, 9.1 mSv (SE, 0.7 mSv) (P < .0001). There was no significant difference in body mass index or image quality between the groups.

CONCLUSIONS

Effective radiation dose in coronary computed tomographic angiography for coronary artery bypass grafting evaluation is very high because of long scan lengths. Prospective electrocardiographic gating significantly reduces effective radiation dose by an average of 76% compared to retrospectively gated scans (9.1 vs 38.4 mSv). In the coronary artery bypass grafting population, prospective electrocardiographic gating should be used whenever ventricular functional assessment is not required.

Evaluation of early coronary graft patency after coronary artery bypass graft surgery using multislice computed tomography angiography

Background

Coronary artery bypass graft (CABG) surgery is the standard of care in the treatment of advanced coronary artery disease, and its long-term results are affected by the failure of bypass grafts. The aim of the present study was to evaluate the early patency rate in coronary bypass grafts.

Methods

A total of 107 consecutive patients who underwent CABG were included in this study. Early graft patency was evaluated via computed tomography (CT) angiography in the first week after surgery.

Results

There were a total of 366 grafts, comprised of 250 venous grafts and 116 arterial grafts. Multi-slice CT detected acute graft occlusions in 32 (8.7%) of all the grafts, including 26 (10%) of the 250 venous grafts and 6 (5%) of the 116 arterial grafts. The patency rates obtained were 97.3% for the left internal mammary (IMA) grafts, 50% for the radial artery grafts, and 50% for the right IMA grafts. Additionally, 107 (96.4%) grafts to the left anterior descending artery (LAD) were classified as patent, whereas 1 (30%) of the 3 grafts in the left circumflex (LCX) region and 1 (50%) of the 2 grafts in the right coronary artery (RCA) territory were found to be occluded. In the venous category, 8 (13.7%) of the 58 grafts to LAD were found to be occluded. In the LCX region, 9 (8.5%) of the 106 grafts were classified as occluded, while the remaining 97 (91.5%) grafts were patent. The venous grafts to RCA were occluded in 9 (10.4%) of the 86 grafts. Amongst the multiple preoperative, intraoperative, and postoperative factors, pump time was significantly longer in the patients with occluded grafts than in those with patent grafts (P = 0.04).

Conclusion

The IMA grafts had the highest early patency rate amongst the coronary bypass grafts. However, the other arterial grafts were associated with a high rate of acute occlusions.

Transitioning from 16-slice to 64-slice multidetector computed tomography for the assessment of coronary artery disease: are we really making progress?

BACKGROUND

Multidetector computed tomography (MDCT) has demonstrated promise in the noninvasive evaluation of coronary artery disease.

OBJECTIVE

To systematically review the literature regarding the improved diagnostic accuracy of 64-slice MDCT.

METHODS

An EMBASE, OVID, PubMed and Cochrane Library database search was performed using the key words 'computed tomography' matched with the terms 'coronary artery' or 'coronary angiography' to identify English-language articles examining MDCT cardiac imaging. Studies that compared 16-slice or 64-slice MDCT with catheter-based coronary angiography for the detection of coronary artery disease in nonrevascularized, poststent and post-coronary artery bypass graft patients were included. Data were pooled to obtain a weighted sensitivity, specificity and diagnostic accuracy for MDCT. Negative and positive predictive values, and likelihood ratios were calculated based on sensitivity and specificity.

RESULTS

Currently, 15 studies involving 1008 patients have examined the efficacy of 64-slice MDCT in the assessment of coronary artery stenosis (more than 50% luminal narrowing). In these studies, 64-slice MDCT has demonstrated a sensitivity (89%), specificity (96%) and diagnostic accuracy (95%) similar to that of 16-slice MDCT. However, 64-slice MDCT was able to assess 5% more coronary artery segments than 16-slice MDCT. In revascularized patients, MDCT can accurately assess both bypass graft occlusion and stenosis. The 64-slice MDCT is also capable of adequately detecting in-stent restenosis. Improvements in spatial and temporal resolution with 64-slice technology have decreased the occurrence of high attenuation and motion artefacts that plagued the previous generation of MDCT scanners.

CONCLUSION

MDCT offers an accurate assessment of the coronary arteries, stented arteries and bypass grafts. The improved accuracy and safety of MDCT may reduce the need for catheter-based coronary angiography.

Evaluation of patients after coronary artery bypass grafting

Modern techniques for coronary artery bypass graft (CABG) are highly successful. Nevertheless, over time, grafts do fail and native coronary artery disease does progress. Follow-up of patients after CABG should focus on secondary prevention, including careful attention to all modifiable risk factors for cardiovascular disease. Routine stress testing with or without imaging is usually not necessary if the patient is asymptomatic and engaging in normal physical activities, including moderate exercise without difficulty. Stress testing with electrocardiographic monitoring alone or in conjunction with nuclear myocardial perfusion imaging or echocardiography is commonly used if a patient develops recurrent symptoms post-CABG or is at particular high risk for complications. Computed tomography coronary angiography is a new, very powerful, noninvasive technique that can directly visualize both CABG and the native coronary arteries. Computed tomography coronary angiography is complimentary to functional stress testing in that it provides anatomic information about graft patency and native coronary artery stenoses, but the functional significance of these findings may still require stress testing with nuclear or ultrasound imaging. Further technical improvements, both in surgical techniques and in imaging, and prospective multicenter trials, are needed to better define the best methods for following patients post-CABG.

Study of coronary artery bypass using the PAS-Port device: assessment by multidetector computed tomography

OBJECTIVE

The use of automatic anastomotic devices in coronary artery bypass grafting surgery is associated with lower patency rates in comparison to conventional anastomosis methods. This is thought to be caused by graft curvature occurring after closing of the chest wall.

METHODS

We evaluated 39 grafts in 28 patients who underwent off-pump coronary artery bypass surgery using the PAS-Port. After surgery, the proximal anastomotic angle of each stent, graft morphology, and patency were evaluated with axial and sagittal views.

RESULTS

The angle for the left anterior descending coronary artery segment was relatively obtuse on the left side of the ascending aorta, and the graft loop formation was not necessary. The angle for the left circumflex coronary artery segment was significantly acute for anastomosis from the upper left side of the ascending aorta. Because grafts are under the constraints of a large loop, graft length tended to become easily excessive or deficient. The angle for the right coronary artery segment was relatively obtuse. The space on the right side of the heart was so narrow that in some cases we had difficulty setting out the appropriate graft location to prevent graft curvature. No bending or stenosis was present in any graft, showing a patency rate of 100%.

CONCLUSION

The short-term results of coronary bypass grafting using PAS-Port are satisfactory.

Non-invasive coronary angiography: the clinical value of multi-slice computed tomography in the assessment of patients with prior coronary bypass surgery. Evaluating grafts and native vessels

BACKGROUND

Contrast enhanced multi-slice computed tomography (MSCT) is the leading modality in non-invasive coronary angiography (CTA) today. We investigated MSCT based assessment of coronary artery bypass grafts (CABG) by analyzing assets and drawbacks of CTA in order to define demands on latest technology.

METHODS

In a clinical setting 39 CABG patients (69.2 +/- 1.4 years; male n = 36) underwent CTA (collimation 16 x 0.75 mm, contrast medium 100 ml; 320 mAs, 120 KV). Ninety-seven CABG (61 venous, 36 arterial grafts) were evaluated. A subgroup of 18 patients underwent additional invasive coronary angiography (CA).

RESULTS

CTA for CABG assessment resulted in an overall sensitivity (sens.) of 100%, specificity (spec.) of 92.4% and positive and negative predictive values (PPV, NPV) of 60% and 100%, respectively. CABG anastomoses showed slightly inferior diagnostic accuracy than other CABG segments. Limitations in imaging quality caused 21% unevaluable segments of the CABG anastomoses. Evaluation of native vessel segments proximal and distal to the anastomoses resulted in a sens, spec, PPV and NPV of 57.5, 94.6, 92 and 67.3%, respectively. With 28.5% unevaluable segments, the native vessel segments showed serious limitations in imaging quality. Radiation exposure was 9.88 +/- 3.20 mSv (9.69 +/- 3.25 mSv male; 12.08 +/- 1.35 mSv female).

CONCLUSION

16-slice MSCT based CABG assessment offers sufficient diagnostic accuracy. However, focussing on the bypass anastomoses and the native revascularized coronary arteries, clinical value is limited.

Rationale, design and methodology for a Prospective Randomized Study of graft patency in Off-pump and On-pump MultI-vessel coronary artery bypasS Surgery (PROMISS) using multidetector computed tomography

Background

Off-pump coronary artery bypass grafting has been accused of possibly compromising graft patency. Sixteen slice computed tomography has shown good diagnostic accuracy in the assessment of coronary bypass graft patency when compared with conventional coronary artery angiography and is less invasive. The study hypothesis is that coronary artery bypass grafting (CABG) performed without cardiopulmonary bypass (Off-Pump) has equivalent early graft patency as if performed with cardiopulmonary bypass (On-Pump) and may have reduced complication rate.

Methods/Design

The Prospective Randomized Comparison of Off-Pump and On-Pump MultI-vessel Coronary Artery BypasS Surgery (PROMISS) is a controlled, single blinded, single centre clinical trial, comparing early graft patency using 16-slice computed tomography in patients with multi-vessel coronary artery disease operated either without or with extracorporeal circulation. Inclusion criteria are multivessel disease with an indication for first time, isolated, non emergent coronary artery bypass grafting with a minimum of three distal anastomoses. Secondary end points are peri-operative mortality, combined morbidity, length of stay, neuro-cognitive testing at 6 weeks and adverse events, stress test and quality of life at 6 months and one year. The sample size of one hundred and fifty patients was calculated in order to enable the detection of a 5% difference in graft patency, with 80% power, considering a minimum of 3 distal anastomoses per patient. Enrolment started in April 2005 and ended July 2007 with study closure in July 2008.

Conclusion

The PROMISS trial aims to shed new light on the effect of Off-Pump as compared to On-Pump coronary artery bypass surgery on graft patency, assessed by multidetector computed tomography, in unselected patients with multivessel coronary artery disease.

Trial Registration

Current Controlled Trials ISRCTN58800729

Sixteen-slice multidetector computed tomography for graft patency evaluation after coronary artery bypass surgery

OBJECTIVE

To investigate the ability of 16-slice multidetector computed tomography (MDCT) to assess coronary artery bypass graft patency and to detect bypass stenosis by comparison with coronary angiography.

METHODS

Thirty patients underwent both conventional coronary bypass angiography and retrospective ECG gated 16-slice multidetector computed tomography after surgery using 0.4 seconds rotation time and 1.25 mm slice thickness.

RESULTS

Among a total of 107 bypass grafts, 101 grafts (94.4%) were evaluable by MDCT. Thirteen patients were taking oral beta blockers. Mean heart rate was 73.6 (52-105). Of the 40 internal mammary arteries and two radial arteries examined, only one was occluded by coronary bypass angiography and MDCT, resulting in a sensitivity of 100% and a specificity of 100%. MDCT correctly diagnosed all patent venous grafts and missed two of the 14 venous grafts shown occluded by conventional angiography resulting in a sensitivity of 85.7% and specificity of 100%. When occluded grafts were excluded, MDCT did not detect two out of two anastomotic arterial graft stenosis >50% and resulted in one false positive result for a sensitivity and specificity of 0% and 97.4%, respectively. MDCT correctly diagnosed one out of three venous stenosis >50% and falsely diagnosed one venous graft stenosis >50% yielding a 33.3% and 97.6% sensitivity and specificity, respectively.

CONCLUSION

Sixteen-slice MDCT allows for noninvasive evaluation of coronary bypass grafts patency with high diagnostic accuracy. Assessment of distal anastomotic stenosis was deficient, particularly for arterial grafts, still limited by low resolution or artifacts. Improved accuracy may be obtained by more aggressive heart rate reduction.

Spiral multislice computed tomography coronary angiography: a current status report

Multislice computed tomography coronary angiography (MSCT-CA) has emerged as a powerful noninvasive diagnostic modality to visualize the coronary arteries and to detect significant coronary stenoses. The latest generation 64-slice computed tomography (CT) scanners is a robust technique which allows high-resolution, isotropic, nearly motion-free coronary imaging. Coronary stenoses are detected with high sensitivity and a normal scan accurately rules out the presence of a coronary stenosis. With the introduction of further novel concepts in CT-technology one may expect that MSCT-CA will become a clinically used diagnostic tool.

Evaluation of temporal windows for coronary artery bypass graft imaging with 64-slice CT

Temporal windows providing the best image quality of different segments and types of coronary artery bypass grafts (CABGs) with 64-slice computed tomography (CT) were evaluated in an experimental set-up. Sixty-four-slice CT with a rotation time of 330 ms was performed in 25 patients (four female; mean age 59.9 years). A total of 84 CABGs (62 individual and 22 sequential grafts) were evaluated, including 28 internal mammary artery (33.3%), one radial artery with sequential grafting (2.4%), and 54 saphenous vein grafts (64.3%). Ten data sets were reconstructed in 10% increments of the RR-interval. Each graft was separated into segments (proximal and distal anastomosis, and body), and CABG types were grouped according to target arteries. Two readers independently assessed image quality of each CABG segment in each temporal window. Diagnostic image quality was found with good inter-observer agreement (kappa=0.62) in 98.5% (202/205) of all graft segments. Image quality was significantly better for saphenous vein grafts versus arterial grafts (P<0.001) and for distal anastomosis to the right coronary compared with other target coronary arteries (P<0.05). Overall, best image quality was found at 60%. Image quality of proximal segments did not significantly vary with the temporal window, whereas for all other segments image quality was significantly better at 60% compared with other temporal windows (P<0.05). Sixty-four-slice CT provides best image quality of various segments and types of CABG at 60% of the RR-interval.

Spyder Aortic Connector System in Off-Pump Coronary Artery Bypass Surgery

PURPOSE

The Spyder aortic connector (Medtronic, Minneapolis, MN) is a new, promising connector device and its safety and efficacy have been evaluated in this study.

DESCRIPTION

Twenty-two patients were randomized to proximal vein graft anastomosis with the Spyder aortic connector (Medtronic) or hand-sewn technique.

EVALUATION

Twenty patients underwent multi-detector computed tomographic scans of the chest 6 months after surgery to evaluate vein graft patency. We have failed to successfully deploy three Spyder connector devices. Thus in this study we have evaluated the graft patency of 19 hand-sewn grafts and of 19 vein grafts anastomosed with the Spyder anastomotic device. Three vein grafts whose proximal anastomosis was accomplished with the Spyder anastomotic connector were occluded and all hand-sewn vein grafts were patent (16% vs 0%; p = 0.23). Stenosis of the proximal anastomosis was observed in seven vein grafts (37%), accomplished with the Spyder anastomotic connector, and in one (5%) hand-sewn vein graft (p = 0.042).

CONCLUSIONS

The results of this study suggest that the use of the Spyder aortic connector device is associated with suboptimal 6-month graft patency.

Evidence based medicine: role of multidetector CT in the follow-up of patients receiving coronary artery bypass graft

PURPOSE

The aim of this study was to define the role of multidetector computed tomography (MDCT) in the follow-up assessment of patients undergoing coronary artery bypass grafting (CABG) using an evidence-based medicine (EBM) approach.

MATERIALS AND METHODS

We performed a literature search of the most reputable studies published in the period 1990-2005 on the clinical follow-up of patients after myocardial revascularisation by CABG. Relevant studies were ranked according to levels of evidence using EBM criteria. A similar search was also conducted on the Internet to identify and review the guidelines posted by the major international scientific societies.

RESULTS

A total of 29 papers meeting the basic reliability requirements of EBM were identified. The reported sensitivity and specificity for electrocardiogram (ECG) testing, stress echocardiography and radionuclide myocardial perfusion imaging were 45% and 82%, 86% and 90%, and 68% and 84%, respectively. All 16 CT studies (one retrospective, the remaining prospective) were validation studies comparing MDCT with conventional coronary angiography. The total number of patients and graft segments studied were 705 and 1,974, respectively. The total number of assessable graft segments were 62%-100%, with a sensitivity and specificity of 75%-100% and 76.9%-100%, respectively.

CONCLUSIONS

The applications of MDCT in the follow-up assessment of patients after CABG are derived from indirect evidence only. The efficacy of the method should be evaluated in randomised clinical trials comparing MDCT not only with conventional coronary angiography but also with other noninvasive stress imaging methods. On the basis of the clinical evidence reported in the literature, the indications for the use of MDCT are still limited. In our view, the completion of such randomised trials combined with the development of new-generation scanners is required to correctly define the role of MDCT in the follow-up assessment of patients who have undergone CABG.

Multi-Detector Computed Tomography in Coronary Artery Bypass Graft Assessment: A Meta-Analysis

Multi-detector computed tomography (MDCT) has become an alternative to coronary angiography in diagnosis of graft occlusion and stenosis after coronary artery bypass. A literature search was performed for studies comparing angiography to 8-slice, 16-slice, and 64-slice MDCT in the assessment of coronary grafts. In assessing occlusion, 14 studies produced pooled sensitivity of 97.6%, specificity of 98.5%, diagnostic odds ratio of 934.2, area under the curve of 0.996, and Q* of 0.977. Ninety-six percent of all grafts were visualized for occlusion assessment. Beta blockers, symptomatic status, and postoperative period did not significantly affect diagnostic performance. Stenosis assessment produced sensitivity of 88.7% and specificity of 97.4%. Eighty-eight percent of patent grafts could be assessed for stenosis. The diagnostic accuracy of MDCT approaches angiography for diagnosing graft occlusion and stenosis in patients with venous and arterial coronary bypass grafts. Our findings show that cardiac surgeons will need to interpret MDCT images of both native and grafted vessels soon in preparation for primary or re-do coronary bypass grafting procedures.