Materials and Methods
The institutional review board reviewed the study protocol and approved the present study as a minimal risk retrospective study (approval number H-2009-014-1154) that did not require individual patient consent. Of the 1746 patients who had undergone isolated CABG between January 2008 and December 2018 at Seoul National University Hospital, off-pump CABG (OPCAB) had been performed in 1711 patients (98.0%). Of the 1711 patients, 1293 patients had received NT SV conduits as a Y- (n=1105) or an I-composite (n=272) graft based on the in situ left ITA for myocardial revascularization. Ninety-four patients had received NT SV conduits as both Y- and I- composite grafts. Early (1.4±1.3 days) postoperative angiograms that were performed in 99.2% of patients (1283/1293) demonstrated 55 occluded SV conduit anastomoses in 53 patients. Of the 53 patients, 46 patients who had 48 occluded SV anastomoses were re-evaluated by 1-year (13.0±1.7 months) postoperative angiographies and were analyzed in the present study. One-year angiograms demonstrated reopened SV conduits in 14 patients (Group R) and persistently occluded SV conduits in 32 patients (Group O)(Figure 1).