Investigating the peri-saphenous vein graft fat attenuation index on computed tomography angiography: relationship with progression of venous coronary artery bypass graft disease and temporal trends.

BACKGROUND

To clarify the fat attenuation index (FAI) change trend of peri-saphenous vein graft (SVG) and determine the association between FAI and graft disease progression based on CCTA images.

METHODS

Patients with venous coronary artery bypass grafts (CABGs) were consecutively enrolled in this retrospective study. In study 1, 72 patients who had undergone 1, 3, and 5 years of CCTA examinations without graft occlusion were recruited, and generalized estimation equation was used to analyze the peri-SVG FAI change trend over time. In study 2, 42 patients with graft disease progression and 84 patients as controls were propensity score-matched. Generalized linear mixed model and continuous net reclassification improvement (NRI) were used for assessing the associations with graft disease progression. Multivariable Cox regression analysis was used for assessing risk factors predicting cardiac events.

RESULTS

In study 1, both the FAI of proximal right coronary artery and SVG decreased over time. In study 2, the 1-year CTA-derived FAI of grafts and graft anastomosis were independent indicators of graft disease progression at the 3-year CCTA follow-up (graft: odds ratio [OR] = 1.106; 95% confidence interval [CI] = 1.030-1.188, P = 0.006; graft anastomosis: OR = 1.170, 95% CI = 1.091-1.254, P < 0.001). Inclusion of the graft anastomosis FAI significantly improved reclassification compared with graft FAI (continuous NRI = 0.638, 95% CI: 0.345-0.931, P < 0.001). Moreover, The graft anastomosis FAI was found to be a risk factor for cardiac events after CABG and no statistically significant difference was found in the graft FAI (graft anastomosis: HR = 1.158, 95% CI = 1.034-1.297, P = 0.011; graft: HR = 1.116, 95% CI = 0.995-1.251, P = 0.061).

CONCLUSIONS

A synchronism was found in the FAI change trend between native coronary artery and venous graft, which both decreased over time. The CCTA-derived FAI of venous grafts showed the potential of demonstrating SVG disease progression and graft anastomosis served as the optimal measured location.