Patients and grouping
Between January 2012 and December 2014, 271 patients with DCAD who received off-pump CABG + CE were included in this study. Exclusion criteria included (1) Presence of one- or double-vessel disease; (2)SYNTAX score ≤ 23; (3) Urgent or emergent CABG; (4) Being concomitant valvular or aortic surgery; (5) Urgent switching from off-pump to on-pump CABG.
Referring to the exclusion criteria, a total of 246 patients were included in this retrospective study. According to the territory and number of CE, patients were divided into LAD group (CE on left anterior descending artery n = 65), RCA group (CE on the right coronary artery, n = 134), and Multi-vessels group [at least CE on two of LAD, RCA and left circumflex artery (LCX), n = 47].
The study was carried out following the Ethical Guideline of the Committee on Human Experimentation of our institution, and informed consent was obtained from the patients about the experimentation (Ethics approval number 2021050X).
Off-pump CABG + CE was performed with a standard procedural protocol involving general anesthesia, median sternotomy, systemic heparinization with activated clotting time (ACT) > 300 s, and harvesting of the left internal mammary artery (LIMA) and saphenous vein (SV). LIMA was always anastomosed to LAD. The sequential SV graft was performed by proximal anastomosis to the ascending aorta firstly, and then distal anastomosis to LCX and RCA in succession. For selected patients with indications, the bilateral internal mammary arteries were used with a composite “Y” graft (LIMA in situ and RIMA grafted to LIMA) .
The CE was performed by as follow indications: (1) Coronary angiography indicating diffuse lesions with length > 2 cm, luminal diameter < 1 mm in the main coronary artery; (2) intraoperative inspection finding no suitable anastomotic location in the middle-distal of the coronary artery with a wide blood supply territory. The atherosclerotic plaque was removed using the closed-CE technique. The closed-CE was performed with the following steps: (1) Coronary knife to make a 5–8 mm arteriotomy at the anastomotic site; (2) Potts scissors to peel intimal plaque from adventitia on both sides of incision; (3) Pull plaque using forceps with the help of the reaction force form heart contracts. The distal end of the plaque needed to be completely peeled. The proximal end of plaque was peeled 3–5 mm and then cut off sharply to avoid competitive flow. A satisfactory standard of closed-CE was that the distal end of plaque was present of a translucent and rat-tail shape with blood back-flow via arteriotomy. If the distal end of plaque was not peeled completely, open-CE with extended arteriotomy and vein patch angioplasty was performed. The diameter of all target vessels for bypass grafting should be ≥ 1.5 mm referring to 1.5 mm coronary probe during operation. The postoperative antithrombotic strategy included (1) Unfractionated heparin to maintain ACT > 180 s from 3 h after surgery to extubation if bleeding < 300 ml in the first 3 h after surgery; (2) Low molecular heparin to bridge-therapy for 3 days after extubation; (3) Dual antiplatelet therapy at 6–24 h after surgery and continuing for one year; (4) One antiplatelet continuing for life.
The primary end-points were PMI and long-term major adverse cardiovascular and cerebrovascular events (MACCE). MACCE included MI, death, redo revascularization, and stroke. The PMI was defined by (1) Postoperative cTnI more than 10 times the 99th percentile of the upper limit of normal reference value with normal preoperative cTnI value; (2) Ongoing evidence of myocardial ischemia including new pathology Q wave formation, coronary angiography confirming the presence of new coronary or grafts occlusion, imaging evidence of new viable myocardium loss or local wall motion abnormalities consistent with ischemic etiology .
The secondary end-points included death in hospital, duration of mechanical ventilation, and ICU stays, mechanical circulation support, and long-term survival. Follow-up was mainly performed by outpatient and telephone interviews, and ended in February 2021. All patients received guideline-directed medical therapy (GDMT) after surgery .
Statistical analysis was performed using an extensively admissive software program SAS software (version 9.4; SAS Institute Inc., Cary, NC, USA). Data were presented as means ± standard deviation (SD) or median with interquartile range for continuous variables and as frequencies and percentages for categorical variables. The ANOVA test was used to address non-paired samples for the comparison of normally distributed parameters and the Wilcoxon rank-sum test for the comparison of non-parametric variables. The Chi-squared test and Fisher's exact test were applied for the comparison of categorical variables. The multivariate logistic regression analysis was performed to calculate odds ratio (OR) and 95% confidence interval (CI) for identifying the risk factors of PMI. Kaplan–Meier survival analysis was performed for long-term survival. Cox proportional hazards model was used for identifying risk factors of long-term MACCE. Differences were considered statistically significant only when the p-value was < 0.05.