Coronary artery bypass graft surgery depends on conduits that stay open, and the saphenous vein graft remains the most frequently used conduit in these procedures despite its known vulnerability to failure. A prospective study conducted at Menoufia University in Egypt, published in the Egyptian Journal of Radiology and Nuclear Medicine, set out to test whether multidetector computed tomography coronary angiography, or MDCT-CA, could reliably replace invasive coronary angiography for evaluating the patency of these vein grafts in postoperative patients. The researchers also examined which clinical factors were associated with graft occlusion in their cohort.
The study enrolled 58 consecutive post-CABG patients who had at least one saphenous vein graft, accounting for 79 grafts in total. The participants included 45 men and 13 women, with ages ranging from 35 to 74 years and a mean age of 58.7 years. All patients were referred from the cardiology department for further cardiac assessment. The interval between the original bypass surgery and the CT examination ranged from 1 to 8 years, and the gap between the CT scan and the invasive angiography reference test was strictly kept within 1 to 4 weeks, minimizing the chance that graft status changed between the two examinations.
Each patient underwent CT angiography on a 128-slice scanner using a retrospective ECG-gated protocol with a slice thickness of 0.625 millimeters. Before scanning, patients fasted for 4 to 6 hours and avoided caffeine, tobacco, and vigorous exercise for at least 12 hours. Heart rate was optimized to below 65 beats per minute with oral beta-blockers when clinically permissible. Nonionic iodinated contrast was injected at a flow rate of 4 to 6 milliliters per second, followed by a saline chaser, with total contrast volumes between 80 and 90 milliliters. Scan coverage extended from just above the clavicles down to the infra-cardiac apex to ensure that both proximal and distal bypass anastomoses were fully visualized.
The reconstructed images were analyzed with multiplanar reformations, curved planar reformations, maximum intensity projections, and three-dimensional volume rendering. A single experienced radiologist classified each graft as patent, significantly stenotic, defined as at least 50 percent luminal diameter reduction, or occluded, defined as complete absence of contrast opacification within the graft lumen. For the risk-factor analysis, patent and narrowed grafts were combined into a non-occluded group and compared with occluded grafts. The invasive coronary angiography, performed through a trans-femoral or trans-radial approach, was interpreted independently by an interventional cardiologist who was blinded to the CT findings, serving as the reference standard.
The results showed that of the 79 saphenous vein grafts analyzed, 46 grafts, or 58.2 percent, were patent, 25 grafts, or 31.6 percent, were occluded, and 8 grafts, or 10.1 percent, were significantly stenotic. The obtuse marginal artery was the most common target vessel, accounting for 48.1 percent of grafts, followed by the right coronary artery at 22.8 percent and the diagonal branch at 15.2 percent. The highest patency rates were observed in grafts to the left anterior descending artery, which reached 100 percent, and to the diagonal branch at 75 percent, while grafts to the right coronary artery showed the highest proportion of stenosis at 44.4 percent. The single graft to the left circumflex artery was narrowed.
Agreement between the two imaging modalities was excellent, with a Cohen’s kappa coefficient of 0.974 and a P value below 0.001. Both modalities identified the same 25 occluded grafts. The CT examination detected 8 stenotic grafts compared with 7 identified by invasive angiography, and this single discrepant case accounted for the only mismatch between the two tests. The authors attributed this discrepancy to overestimation of luminal narrowing, likely driven by blooming artifacts from dense focal calcifications or adjacent metallic surgical clips, which remain documented technical challenges in cardiovascular CT interpretation.
Measured against the invasive reference standard, CT angiography achieved a sensitivity of 100 percent, a specificity of 97.9 percent, a positive predictive value of 97.0 percent, a negative predictive value of 100 percent, and an overall diagnostic accuracy of 98.7 percent for detecting abnormal grafts. The authors note that these figures closely mirror those reported by an earlier study of 122 bypass grafts, which found a nearly identical kappa coefficient of 0.971, and are consistent with a meta-analysis of 15 studies that reported pooled sensitivity and specificity of 97.6 percent and 96.7 percent for detecting total occlusion or hemodynamically significant graft stenosis. The relatively strong performance of CT in bypass grafts, which can exceed its performance in native coronary arteries, is attributed to the wider luminal caliber of venous grafts, their more predictable surgical path, and their lower burden of diffuse calcification.
On the risk-factor side, the analysis found that diabetes mellitus was significantly associated with graft occlusion on univariate analysis, with a P value of 0.001, and that a postoperative duration exceeding 5 years was also significantly associated with occlusion, with a P value of 0.003. Hypertension showed only a borderline association, at P equal to 0.053. Age, sex, family history of coronary artery disease, smoking, and dyslipidemia showed no statistically significant associations with occlusion in this cohort. The authors caution that because the study was cross-sectional and did not include serial graft assessments, the exact timing of graft occlusion could not be determined, and the association with longer postoperative duration should not be interpreted as a time-to-event or causal relationship. They also emphasize that the risk-factor analysis was univariate, without multivariable adjustment, so the identified associations should not be considered independent predictors, and some patients contributed more than one graft, a clustering effect the analysis did not account for.
The study’s limitations are substantial and are acknowledged in detail. The sample was small and drawn from a single academic institution, limiting generalizability. The number of patients initially screened and excluded could not be determined from the available records, so a patient flow diagram could not be provided, restricting assessment of selection bias. The cohort was referral-based, with most patients imaged because of symptoms or suspected ischemia and only a minority undergoing routine follow-up, meaning the diagnostic performance estimates apply primarily to clinically referred post-CABG patients rather than to population-based screening of asymptomatic individuals. The CT examinations were read by a single radiologist, so interobserver variability could not be assessed, and arterial grafts were not evaluated at all.
The authors also stress that anatomical graft occlusion does not necessarily imply an adverse clinical outcome, since its impact may vary with the severity of the underlying native coronary disease, the myocardial territory supplied by the graft, the presence of competitive native coronary flow, and the extent of myocardial ischemia. Detailed information on preoperative native coronary stenosis severity and objective ischemia evidence was not systematically available, and subsequent repeat revascularization was not a predefined endpoint. Within those constraints, the study concludes that MDCT coronary angiography demonstrated excellent agreement and high diagnostic accuracy against invasive angiography for assessing saphenous vein graft patency in clinically referred post-CABG patients, and that diabetes mellitus and longer duration since surgery were associated with anatomical occlusion on univariate analysis. The authors recommend larger multicenter prospective studies with multivariable adjustment, longitudinal follow-up, and systematic assessment of clinical outcomes to validate these findings and clarify the long-term significance of graft stenosis and occlusion.
Subject of Research: Diagnostic performance of MDCT coronary angiography for evaluating saphenous vein graft patency after coronary artery bypass surgery
Article Title: MDCT coronary angiography for assessment of saphenous vein graft patency and associated clinical risk factors
Article References: Turky, A. A., Maaly, M. A., Ghazy, T. E., & Abdellatif, H. A. (2026). MDCT coronary angiography for assessment of saphenous vein graft patency and associated clinical risk factors. Egyptian Journal of Radiology and Nuclear Medicine, 57(1), Article 222. https://doi.org/10.1186/s43055-026-01886-x
Image Credits: AI Generated
DOI: 10.1186/s43055-026-01886-x
Keywords: saphenous vein graft, coronary artery bypass grafting, MDCT coronary angiography, invasive coronary angiography, graft patency, graft occlusion, diabetes mellitus, diagnostic accuracy, postoperative surveillance, coronary artery disease, Cohen's kappa, prospective study
News Source: Ophelia Keating. (October 29, 2026). CT angiography matches invasive angiography for checking bypass vein graft patency. Scienmag.
