Left internal mammary artery bypass dysfunction after revascularization of moderately narrowed coronary lesions. Colour-duplex ultrasound versus angiography study.

BACKGROUND: The left internal mammary artery (LIMA) is the conduit of choice for revascularization of coronary arteries and its popularity further increases in the era of mini-invasive coronary surgery. The aim of this study was first, to assess the accuracy of CDUS in predicting the LIMA graft dysfunction as compared to angiography, and secondly, to correlate the postoperative status of the LIMA graft with preoperative coronary artery stenosis severity of the bridged lesion. METHODS AND RESULTS: We examined 111 patients (pts) by colour-duplex ultrasound after myocardial revascularization by LIMA bypass (3.8 +/- 3.2 years after revascularization). LIMA was detected from the left supraclavicular approach at rest using the 7.5 MHz linear transducer. The ultrasound results were compared to contemporaneous angiography. The LIMA bypass patency was correlated with the preoperative coronary artery stenosis severity. The LIMA was detected by ultrasound in 92.8% (103) pts. At angiography, LIMA was patent and functional in 85 pts (76.6%, group A); in 25 subjects LIMA was stenosed or dysfunctional (22.5%, group B). In one patient the coronary subclavian steal syndrome was detected (0.9%). Haemodynamically moderate stenosis (50-60% by preoperative quantitative coronary angiography) was grafted in 5 pts of group A (6%), but in 10 pts of group B (40%) (P < 0.0001 vs group A). A peak systolic to peak diastolic velocity ratio (SDVR) of <2.0 yielded optimal accuracy to detect the absence of LIMA bypass dysfunction with a negative predictive value of 95%. CONCLUSION: 1. Revascularization of angiographically moderate coronary lesions is associated with a higher risk of postoperative graft dysfunction. 2. Colour-duplex ultrasound is a useful non-invasive tool for the postoperative follow-up of pts with a LIMA graft.