Analysis of saphenous vein graft lesion composition using near-infrared spectroscopy and intravascular ultrasonography with virtual histology.

Objective: To examine the composition of saphenous vein graft (SVG) lesions using two novel modalities, near-infrared spectroscopy (NIRS) and intravascular ultrasonography with virtual histology (IVUS-VH).

Methods: We performed NIRS and IVUS-VH imaging of 23 SVGs in 21 patients undergoing clinically-indicated angiography.

Results: Mean patient and SVG age was 66±7 and 10±7 years, respectively. SVG lesion location was aorto-ostial in 8 (35%), body in 13 (57%) and distal anastomotic in 2 (9%). Compared to anastomotic lesions, body lesions had larger mean lumen area (6.4±1.8 mm2 vs. 4.2±6.4 mm2, P=0.02) but similar mean plaque burden (73±5% vs. 70±10%, P=0.66). A NIRS lipid core plaque was identified in 9 of 13 body lesions vs. 1 of 10 anastomotic lesions (69% vs. 10%, P=0.005). SVG body lesions had higher lipid core burden index (LCBI) compared to anastomotic lesions (184±76 vs. 49±54, P<0.001). By IVUS-VH, SVG lesions had high % necrotic core (28±10%) and % dense calcium (13±10%), without any significant difference between body and anastomotic sites. Older SVG age was associated with higher lesion and vessel LCBI (r=0.76 and r=0.64, respectively, P<0.001), but was not associated with IVUS-VH determined plaque composition. Higher HDL-cholesterol was associated with lower lesion LCBI (r=-0.43, P=0.04).

Conclusions: NIRS-measured lipid core plaque in SVGs increases with increasing SVG age and is infrequent in anastomotic lesions. No association was found between IVUS-VH plaque composition measurements and SVG lesion location or age.