Baseline characteristics
There were 1867 patients who underwent CABG from July 2020 to December 2022 in Nanjing First Hospital. Of which 1309 patients got isolate CABG for first time (Detailed excluding process is shown in Fig. 1.). Totally 1247 patients used saphenous vein including 849 with OVH and 398 with EVH. In the original cohort, EVH group had a higher proportion of female, hypertension, hyperlipidemia, peripheral arterial disease(PAD), history of PCI, angina and acute coronary syndrome(all P < 0.05), meanwhile patients in EVH group had a higher body mass index(BMI), more 3 vessel disease and left main disease. After propensity score matching, 308 pairs successfully matched with baseline SMDs < 0.1 for all baseline characteristics(Table 1).
In-hospital outcomes
The surgical information and postoperative in-hospital outcomes in the PSM groups are shown in Table 2. With the surgical information, patients in the EVH group had more numbers of vein graft (3 vs. 2, P < 0.001) and the OVH group had more intraoperative blood transfusion (19.5% vs. 35.3%, P < 0.001). There were no significant differences in operating time, CPB use and LIMA use between cohorts. EVH patients had more rates of acute kidney injury (8.5% vs. 4.2%, P = 0.045) and less prolonged mechanical ventilation (4.9% vs. 10.1%, P = 0.023). Death in hospital rates (2.3% vs. 1.3%, P = 0.543) and other in hospital postoperative outcomes (ICU stay time, low cardiac output, cardiac arrest, reoperation for bleeding and cerebral vascular accident) did not show the differences in the groups. The similar tendencies were observed between the cohorts before propensity matching (Supplementary Material, Table S1.)
Table 2
Surgical information and postoperative in hospital outcomes in propensity matched patients with open vein harvesting and endoscopic vein harvesting.
|
EVH group
(n = 308)
|
OVH group
(n = 308)
|
P value
|
Operating time, median(IQR), min
|
260(230,300)
|
265(225,300)
|
0.635
|
Cardiopulmonary bypass use, n(%)
|
264(85.7)
|
264(85.7)
|
0.840
|
CPB time, median(IQR), min
|
97(80,117)
|
96(82,115)
|
0.573
|
ACC time, median(IQR), min
|
62(50,77)
|
63(51,79)
|
0.756
|
Use of LIMA, n(%)
|
297(96.4)
|
297(96.4)
|
1.000
|
Numbers of vein graft, median(IQR), min
|
3(2,3)
|
2(3,4)
|
< 0.001
|
Intraoperative blood transfusion, n(%)
|
57(19.5)
|
108(35.3)
|
< 0.001
|
ICU time, median(IQR), day
|
1(1,2)
|
1(1,2)
|
0.119
|
Low cardiac output, n(%)
|
10(3.3)
|
12(3.9)
|
0.840
|
Cardiac arrest, n(%)
|
3(1.0)
|
3(1.0)
|
1.000
|
Reoperation for bleeding, n(%)
|
3(1.0)
|
5(1.6)
|
0.725
|
Readmitted to ICU, n(%)
|
6(1.9)
|
8(2.6)
|
0.787
|
Acute kidney injury, n(%)
|
26(8.5)
|
13(4.2)
|
0.045
|
Prolonged mechanical ventilation, n(%)
|
15(4.9)
|
31(10.1)
|
0.023
|
Cerebral vascular accident, n(%)
|
13(4.3)
|
16(5.2)
|
0.717
|
Death in hospital, n(%)
|
7(2.3)
|
4(1.3)
|
0.543
|
OVH: open vein harvesting. EVH: endoscopic vein harvesting. IQR: interquartile range. CPB: cardiopulmonary bypass. ACC: aortic cross clamping. LIMA: left internal mammary artery. |
Table 3
Intraoperative transit time flow measurement between endoscopic and open vein harvesting patients in different target vessels.
Target vessel
|
Variables
|
EVH group
Mean(SD)
|
OVH group
Mean(SD)
|
Difference*
|
95% CI
|
P-value
|
LAD systems
(n = 173, 133)
|
MGF
|
35.2 (17.99)
|
34.4 (19.53)
|
0.56
|
-3.66, 4.78
|
0.796
|
PI
|
2.0 (1.08)
|
2.6 (3.59)
|
-0.57
|
-1.14, -0.01
|
0.049
|
LCX systems
(n = 228, 183)
|
MGF
|
42.1 (26.32)
|
36.6 (26.87)
|
4.43
|
-0.65, 9.51
|
0.088
|
PI
|
2.2 (1.22)
|
2.5 (1.69)
|
-0.27
|
-0.55, 0.01
|
0.062
|
RCA systems
(n = 263, 209)
|
MGF
|
40.4 (24.45)
|
36.4 (21.08)
|
3.41
|
-0.75, 7.57
|
0.109
|
PI
|
2.5 (2.12)
|
2.3 (1.86)
|
0.26
|
-0.11, 0.62
|
0.170
|
Total
(n = 664, 525)
|
MGF
|
39.6 (23.76)
|
35.9 (22.89)
|
3.10
|
0.45, 5.75
|
0.022
|
PI
|
2.3 (1.62)
|
2.4 (2.37)
|
-0.14
|
-0.36, 0.09
|
0.240
|
*The differences were adjusted for the diameters of corresponding target vessel. MGF: mL/min |
EVH: endoscopic vein harvesting. OVH: open vein harvesting. CI: confidence interval. MGF: mean graft flow. PI: pulsatility index. |
TTFM results in CABG
All patients received intraoperative TTFM during the surgery. There are totally 1189 saphenous vein grafts(SVGs) from 616 patients could be counted(664 in EVH group and 525 in OVH group). Depending on differences of the target vessels, we categorized them as LAD system(including LAD, Diagonal), LCX system(including OM) and RCA system(including RCA, PL and PDA). Most SVGs showed well fluency with the averages of MGF over 30mL/min and PI < 3.0. The EVH grafts had higher MGF(39.6 mL/min vs. 35.9 mL/min, P = 0.022) than OVH grafts with nearly the same PI(2.3 vs. 2.4, P = 0.240). There were no significant differences in MGF between groups when categorize the SVGs with target vessels.
Survival analysis
There were 19 patients who had in-hospital death with 10 in EVH group. The main reason of in-hospital death was ventricular arrhythmia(42.1%, 5/10 in EVH group, 4/9 in OVH group). The median (interquartile range) follow-up time was 1.5 (1.0–2.0) years in EVH cohort and 1.67 (1.0-2.25) years in OVH cohorts. Totally 28 patients were lost to follow-up (2.0%), and no significant difference was found between 2 cohorts (2.5% vs. 1.6%, P = 0.301).
The all-cause death rate had no significant difference in different vein harvesting during the 3 years follow-up. The rate of death from all cause was 8.5% in EVH cohort vs 5.0% in OVH cohort (HR 1.565, 95%CI: 0.77–3.17, Log-rank P = 0.21) (Fig. 2A). After adjusting for death from non-cardiovascular causes as a competing risk, death from cardiovascular causes was 1.7% in EVH group vs 2.5% in OVH group(HR 0.769, 95%CI: 0.25–2.39, Log-rank P = 0.65)(Fig. 2B).
As the secondary outcomes, no significant differences were observed in the incidence of MACEs(8.1% vs. 7.1%, HR 1.165, 95CI: 0.51–2.69, Log-rank P = 0.71)(Fig. 2C) and asymptomatic survival(66.7% vs. 72.5%, HR 1.117, 95%CI: 0.65–1.92, Log-rank P = 0.68)(Fig. 2D) after adjusting death as a competing risk. The same results were observed in the original cohorts (Figure S1).