Hemodynamic evaluation of coronary artery bypass graft lesions using fractional flow reserve

Abstract

Coronary angiography is limited by its inability to assess the hemodynamic significance of a coronary artery stenosis. The assessment of the physiological significance of saphenous vein graft (SVG) lesions with a pressure wire to determine the fractional flow reserve (FFR) is lacking. FFR was determined in 10 SVG lesions of 10 males who had stress myocardial perfusion imaging (MPI) prior to referral for percutaneous coronary intervention for clinical indications. All SVGs had a diameter stenosis (DS) > 50% and 30% had a DS > or = 70%. A significant FFR was present in 30% of patients. Ischemia along the territory of the SVG was present in 20% of patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FFR < 0.75 for the detection of ischemia on stress MPI were 50, 75, 33, 85, and 70%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FFR < 0.75 for detecting > or = 70% DS on angiography were 33, 71, 33, 71, and 60%, respectively. There was no significant correlation between FFR and % DS (R(2) = 0.1, P = 0.35). The use of FFR to assess the physiological significance of SVG lesions is feasible and provides an acceptable specificity and negative predictive value compared to stress MPI.