Evaluation of graft patency by computed tomographic angiography in symptom-free post-coronary artery bypass surgery patients

Background  Accelerated atherosclerosis occurs in aortocoronary saphenous vein grafts, contributing to increased morbidity and mortality rates. We estimated the prevalence of asymptomatic graft failure in patients 5 years or more after coronary artery bypass grafting (CABG) using electron-beam computed tomographic angiography (EBA). Methods and Results  EBA was performed in 45 symptom-free patients (mean age, 66±9 year; 87% male; mean time interval after CABG, 8±5 years). A total of 102 vein grafts and 37 internal mammary artery grafts were evaluated. Patients with graft stenosis or occlusion on EBA underwent myocardial perfusion scintigraphy and invasive angiography. Six grafts were unevaluable by EBA. Twenty patients had evidence of graft stenosis or occlusion on EBA. Of 20 asymptomatic patients with graft disease, 17 (85 %) had abnormal myocardial perfusion, with moderate to severe reversible ischemia occurring in one third of subjects. Fourteen occluded and eleven stenosed vein grafts were correctly diagnosed by EBA. There were 2 false-positive EBA diagnoses of graft stenosis, resulting in a 100 % positive predictive accuracy for detecting graft occlusion and 85% positive predictive accuracy for detecting graft stenosis. All occluded internal mammary artery grafts (n=3) were accurately diagnosed. Conclusion  Computed tomographic coronary angiography permits reliable identification of by pass graft stenoses and occlusion in symptom-free patients more than 5 years after CABG. Future studies are needed to assess the prognostic benefit of early detection of graft disease and intervention in asymptomatic patients The study was supported by research grants from the Harrow Cardiovascular Research Trust