Reply to Lobo Filho<i>et al.</i>

We would like to thank professor Lobo Filho et al. [ 1 ] for the interest in our manuscript [ 2 ] presenting an alternative to conventional coronary artery bypass grafting (CABG) involving a composite-sequential graft to bypass the anterolateral coronary artery territory. Current practice guidelines strongly recommend using the left internal mammary artery (LIMA) to bypass the left anterior descending artery (LAD). The use of composite grafts allows reducing the need for aortic manipulations and associated stroke risk while still providing complete revascularization. In this context, we developed a new strategy using the LIMA for blood inflow and a saphenous vein bridge (SVB) (LIMA-SVB) to distribute the LIMA blood almost directly to the LAD but also to other anterolateral coronary targets such as diagonals, ramus inter-medius or high first obtuse marginal branches. In this technique, a short saphenous vein graft (SVG) is anastomosed to the LAD and the other anterolateral coronary arteries, and the LIMA is connected to the roof of the SVB just above the SVG-LAD anastomosis. This simple strategy is useful in several patients as it is associated with numerous advantages: easy-going off-pump CABG, limiting the length of the SVG required, ease of performing a direct SVG anastomosis to the LAD, increased blood flow in the LIMA pedicle, and favourable clinical and radiological outcomes [ 2 ]. As mentioned by Lobo Filho et al. [ 3 ], we also believe that the use of an SVG in combination with the LIMA could improve the long-term patency of the SVG. As suggested [ 3 , 4 ], we believe that the use of a valveless SVG may improve the patency of the conduit. Since the instauration of the LIMA-SVG technique by our team, we do pay attention to the choice of the SVG segment to be used in the LIMA-SVB. We believe that a valveless segment is preferable, and the diameter of the SVG should match the LIMA as closely as possible. In the ongoing prospective-randomized clinical trial AMI-PONT (ClinicalTrials.gov NCT01585285 [ 5 ], CIHR funded), we are assessing whether the LIMA-SVB patency is not inferior to the conventional CABG strategy combining a separated LIMA graft to the LAD and an SVG to the other coronary artery in the anterolateral territory. To avoid the risk of competitive flow that can jeopardize the LIMA-SVB patency, we require a significant stenosis of >70% of all the native coronaries connected to the LIMA-SVB. Intraoperative blood flow is measured quantitatively with the MediStim Flowmeter (Medtronic, MN, USA) in the LIMA pedicle with and without temporary occlusion of the SVB, and in the SVG itself. We found the graft flow in the LIMA pedicle to be higher in the LIMA-SVB compared with the LIMA-LAD alone [ 2 ]. If the venous segment is patent and there is no competitive flow, the sum of the measured flow into the SVB and the LIMA when the SVB is occluded should be similar to the flow in the LIMA pedicle without occlusion of the SVB. Moreover, during graft patency assessment by cardiac computed tomography angiography, we are also recording the presence of valves, if any, in the short venous segment used in the LIMA-SVB. Conflict of interest: none declared.

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