Abstract
OBJECTIVES
The aim of this study was to evaluate the mid-term outcome of coronary endarterectomy (CE) combined with coronary artery bypass grafting (CABG) and explore the potential risk factors for adverse events.
METHODS
A total of 208 consecutive patients underwent CE between 2008 and 2018 in our centre, of which 198 were included in this retrospective cohort study. The primary end point was major adverse cardiovascular and cerebrovascular events (MACCEs). Kaplan–Meier analysis was performed to evaluate event-free survival, whereas subgroup analysis and Cox regression were used to explore risk factors for the outcomes.
RESULTS
The median follow-up time was 34.7 months. CE + CABG was performed mainly on the left anterior descending artery (42.3%) or right coronary artery (42.3%). Both operative mortality and incidence of perioperative myocardial infarction were 1.5%. The overall survival at 3 and 5 years was 98.0% and 95.9%, whereas the MACCE-free survival was 93.7% and 89.4%, respectively. No significant difference in the incidence of MACCE was observed between on-pump and off-pump CE (P = 0.256) or between left anterior descending artery and non-left anterior descending artery endarterectomy (P = 0.540). Advanced age (>65 years) was associated with a higher risk of MACCE both in univariate [hazard ratio (HR) 3.62, 95% confidence interval (CI) 1.37–9.62; P = 0.010] and multivariate analysis (HR 3.59, 95% CI 1.32–9.77; P = 0.013).
CONCLUSIONS
When performed by experienced surgeons, CE + CABG could be an acceptable approach to achieve complete revascularization of diffusely diseased coronary arteries with satisfactory outcomes, although advanced age might increase the risk of MACCE.
Keywords: Coronary endarterectomy, Coronary artery bypass grafting, Complete revascularization, Diffusely diseased coronary artery
Coronary endarterectomy (CE) has been developed and applied to the treatment of coronary artery diseases [1–3] since the 1950s.
INTRODUCTION
Coronary endarterectomy (CE) has been developed and applied to the treatment of coronary artery diseases [1–3] since the 1950s. However, early studies reported that CE was associated with higher postoperative mortality and more complications (e.g. myocardial infarction) [4, 5]. As a result, coronary artery bypass grafting (CABG) took the place of CE as soon as it was developed. Since then, many cardiac surgeons have been highly conservative about performing CE.
Incomplete revascularization could substantially affect the survival and quality of life of patients with coronary artery diseases [6, 7]. However, with the rapid development of percutaneous coronary intervention, cardiac surgery departments are now handling more patients with diffusely diseased or severely calcified coronary lesions, making it a huge challenge for cardiac surgeons to achieve complete revascularization. Therefore, CE has gained more interest than ever before due to its advantages for performing complete revascularization combined with CABG.
More recently, some studies have shown satisfactory short- and long-term outcomes after CE+CABG [8–10]. This result might be attributed to improved surgical techniques, careful perioperative management and effective antithrombotic therapy after the operation. However, recent evidence from several meta-analyses suggests that CE + CABG reduced the patency of the graft [11] and increased early and late mortality as well as the risk of complications [12, 13] compared with conventional CABG. Wang et al. [14] reported in a meta-analysis of 10 529 patients that CE + CABG increased short-term mortality by 61%, which became more pronounced at the mid-term follow-up. Therefore, more evidence is needed to validate the efficacy and safety of CE + CABG.
The aim of this study was to evaluate the clinical outcomes of CE + CABG in a single-centre cohort of consecutive patients treated over a 10-year period and to explore potential factors related to patient outcome.
PATIENTS AND METHODS
Study design
In this single-centre cohort study, we retrospectively recruited patients who underwent CE + CABG between September 2008 and July 2018 at Fuwai Hospital (Beijing, China) to evaluate the impact of CE on short- and mid-term mortality and the incidence of major adverse cardiac and cerebrovascular events (MACCEs). We also studied potential risk factors for CE on patient outcome. The institutional review board at Fuwai Hospital approved the use of clinical data for this study (ID: 2019-1151) and waived individual informed consent on 26 June 2019.
Study population and operative techniques
We included patients who underwent CE + CABG during the study period at Fuwai Hospital. We excluded patients who underwent CE without CABG and those who concurrently had valve surgery or ventricular aneurysm surgery. The baseline characteristics of the patients were collected from hospital records. In the subgroup analysis, the patients were grouped by detailed intraoperative techniques, such as the use of on-pump or off-pump strategies and endarterectomy involving the left anterior descending artery (LAD) or not.
CE + CABG operations were performed by 26 cardiac surgeons who had sufficient experience with CABG and could accomplish CE whenever feasible. Because CE is a technically demanding procedure, we also studied differences in MACCE among the patients treated by these surgeons. CE was indicated for patients with (i) a long-segment, diffusely diseased or severely calcified coronary artery; or (ii) severe long-segment in-stent restenosis, complicated with or without occlusions of major side branches. Because anastomosis of graft vessels is barely possible for coronary arteries meeting these indications, CE + CABG was the final option for achieving complete revascularization of these target vessels. Of note, the final decision to perform CE was based on the results of intraoperative evaluation of the target lesions.
Operations were performed with or without cardiopulmonary bypass; the closed CE technique was preferred. The details of the CE techniques are as follows: (i) closed CE: a small incision was made on the adventitia of the target coronary artery, followed by a small segmental dissection of the intima from the vessel wall; then the plaque was held by tweezers, and, while a dissector was used during the on-pump procedure, proper tension was applied gently to counteract the beating of the heart during off-pump surgery until the atherosclerotic plaque was completely dissected from the vessels. (ii) Open CE: a long-segment incision was made on the adventitia of the target coronary artery, with the length of the incision being as long as possible to cover the lesion completely. The dissector was used to carefully separate the plaque from the vessel wall; if the distal part of the target vessels was too small to allow an incision, removal of the distal plaques was completed using techniques similar to those used in closed CE.
Definitions and follow-up
Advanced age was defined as age >65 years. Preoperative renal failure was defined as a history of chronic renal failure or preoperative creatinine >133 μmol/l. Perioperative myocardial infarction was diagnosed according to the fourth universal definition of myocardial infarction [15]. Operative death was defined as death within 30 days after the operation, including death in the hospital or after discharge.
The primary end point was the incidence of MACCE, which was a composite of all-cause death, non-fatal myocardial infarction, stroke (including haemorrhagic and ischaemic events) and repeat revascularization. Patients were required to return to the institute for routine re-examinations at 3, 6 and 12 months after the operation. For patients who survived more than a year, the follow-up was made annually thereafter. Phone call interviews were used to contact patients unavailable for re-examination at the hospital, and home visits were made to those who were not contacted by telephone for final confirmation of the patients’ status.
Statistical analyses
Continuous variables are presented as mean ± standard deviation if they follow a normal distribution and were evaluated using the Student’s t-test. Otherwise, they are presented as medians with the 25th and 75th percentiles and tested by the Wilcoxon’s rank-sum test. Categorical variables are presented as n (%) and tested by the χ2 test or the Fisher’s exact test, as appropriate. The Shapiro–Wilk test was used to confirm whether or not the continuous variables were normally distributed. The cumulative survival rate and the MACCE-free survival rate were calculated using the Kaplan–Meier method and compared using the log-rank test. Univariable Cox regression was performed to study the possible risk factors for MACCE after CE + CABG, followed by multiple adjustments. Cox regression was also performed in the subgroup analysis to adjust the possible confounding variables. A P-value <0.05 was considered statistically significant. Statistical analyses were performed using Stata 15.0 (StataCorp, College Station, TX, USA).
RESULTS
Patient characteristics and intraoperative details
From September 2008 to July 2018, a total of 208 consecutive patients (about 0.55% of the overall patients who received CABG at the institute) underwent CE. Ten patients were excluded for specific reasons (Fig. 1). Among them, 1 patient was excluded due to severe damage to the vessel wall after CE, which did not allow the performance of CABG. Baseline characteristics are summarized in Table 1. The mean age was 60.3 ± 9.3 years. Among all the patients, 152 (75.4%) were men, 80 (38.7%) had a prior myocardial infarction and 81 (39.1%) had diabetes mellitus. The mean preoperative ejection fraction was 59.0% ± 9.0%, whereas 97 patients (46.9%) were rated as New York Heart Association (NYHA) functional class III or IV.
Figure 1:
Patient selection flow chart. CABG: coronary artery bypass grafting; CE: coronary endarterectomy; LAD: left anterior descending artery; LCX: left circumflex artery; RCA: right coronary artery; TV: 2-vessel.
Table 1:
Preoperative clinical characteristics
| Characteristics | (N = 198) |
|---|---|
| Age (years), mean ± SD | 60.3 ± 9.3 |
| Male gender, n (%) | 152 (75.4) |
| History of PCI, n (%) | 31 (15.7) |
| History of arrhythmia, n (%) | 17 (8.6) |
| Atrial fibrillation, n (%) | 6 (3.0) |
| Congestive heart failure, n (%) | 10 (5.1) |
| Hypertension, n (%) | 132 (66.7 ) |
| Dyslipidaemia, n (%) | 161 (81.3) |
| Stroke, n (%) | 32 (16.2) |
| Smoking, n (%) | 123 (62.1) |
| Smoking within 1 month, n (%) | 40.1 (20.7) |
| Diabetes mellitus, n (%) | 77 (38.9) |
| Insulin users, n (%) | 44 (22.2) |
| Renal failure, n (%) | 5 (2.5) |
| Haemodialysis, n (%) | 0 |
| Chronic obstructive pulmonary disease, n (%) | 1 (0.5) |
| Peripheral artery disease, n (%) | 20 (10.1) |
| Previous cardiac operation, n (%) | 3 (1.5) |
| Previous CABG, n (%) | 1 (0.5) |
| Prior myocardial infarction, n (%) | 77 (38.9) |
| Body mass index (kg/m2), n (%) | 25.5 (23.7,27.7) |
| CCS class III or IV, n (%) | 113 (57.1) |
| NYHA class III or IV, n (%) | 90 (45.5) |
| Triple vessel disease, n (%) | 124 (62.6) |
| Left main disease, n (%) | 34 (17.2) |
| Preoperative ejection fraction (%), mean ± SD | 59.3 ± 8.8 |
| LVEDD (mm), mean ± SD | 50.0 ± 5.4 |
| Non-elective operation, n (%) | 3 (1.5) |
| EuroSCORE II (%), mean ± SD | 1.5 ± 1.2 |
CABG: coronary artery bypass grafting; CCS: Canadian Cardiovascular Society; LVEDD: left ventricular end-diastolic diameter; NYHA: New York Heart Association; PCI: percutaneous coronary intervention; SD: standard deviation.
Intraoperative details are shown in Table 2. The mean number of distal anastomoses was 3.3 ± 0.9, and an on-pump procedure was performed in 76 (38.4%) patients. Revascularization of the LAD was required in 197 (99.5%) patients, 183 (92.4%) of whom had an internal mammary artery graft to the LAD. CE was performed on 208 target vessels; 186 (89.4%) of these were completed by the closed CE technique. Open CE was performed mainly on the LAD, especially when the septal perforators were involved. Of these 208 target vessels, CE was performed mainly on the LAD [88 (42.3%)] or the right coronary artery [88 (42.3%)]. Other vessels for endarterectomy included 18 (8.7%) left circumflex arteries and 14 (6.7%) diagonal arteries or the ramus intermedius. Ten patients had CE on 2 coronary targets. The intra-aortic balloon pump was used perioperatively in 7 (3.4%).
Table 2:
Intraoperative patient characteristics
| Variables | N = 198 |
|---|---|
| Distal anastomosis, mean ± SD | 3.3 ± 0.9 |
| Operation time (min), mean ± SD | 211.1 ± 63.3 |
| On-pump | 244.8 ± 62.8 |
| Off-pump | 190.1 ± 54.1 |
| On-pump surgery, n (%) | 76 (38.4) |
| CPB duration (min), mean ± SD | 113.0 ± 5.0 |
| Aortic cross-clamp time (min), mean ± SD | 75.5 ± 41.2 |
| Revascularization of LAD, n (%) | 197 (99.5) |
| IMA to LAD | 183 (92.4) |
| Use of grafts | |
| IMA, n (%) | 195 (98.5) |
| Left IMA | 187 (94.4) |
| Right IMA | 4 (2.0) |
| Free IMA | 4 (2.0) |
| RA or other arterial graft | 10 (5.1) |
| Venous graft | 190 (96.0) |
| CE, n | 208 |
| Left anterior descending, n (%) | 88 (42.3) |
| Right coronary artery, n (%) | 88 (42.3) |
| Left circumflex artery, n (%) | 18 (8.7) |
| Othera, n (%) | 14 (6.7) |
| Closed CE, n (%) | 186 (89.4) |
| Intraoperative graft flow (ml/min) | |
| LAD CE, median (range) | 30.0 (12.5–43.3) |
| Non-LAD CE, median (range) | 27.0 (16.0–40.0) |
| Perioperative IABP, n (%) | 7 (3.4) |
Included ramus intermedius and diagonal branches.
CE: coronary endarterectomy; CPB: cardiopulmonary bypass; IABP: intra-aortic balloon pump; IMA: internal mammary artery; LAD: left anterior descending artery; RA: radial artery; SD: standard deviation.
Early postoperative outcomes
Postoperative characteristics are summarized in Table 3. Among these patients, 22 (11.1%) received red blood cell transfusions (2.5 ± 1.4 units), whereas 17 (8.6%) received plasma transfusions (482.4 ± 212.8 ml). The intensive care unit stay was 40.0 (21.0–75.0) h. Pericardial effusion was present in 5 patients (2.5%), and 4 (2.0%) underwent re-exploration for bleeding. Postoperative new-onset atrial fibrillation was observed in 31 patients (15.7%). Operative death occurred in 3 (1.5%) patients, and the causes of death were intraoperative ventricular fibrillation, severe postoperative pulmonary infection and acute kidney failure followed by multiple organ dysfunction syndrome, respectively. Perioperative myocardial infarction was observed in 3 patients (1.5%). Overall, the 30-day MACCE-free survival was 98.0%.
Table 3:
Postoperative and follow-up outcomes
| Variables | (N = 198) |
|---|---|
| Postoperative outcomes | |
| Perioperative transfusion, n (%) | 33 (16.8) |
| Red blood cells | 22 (11.1) |
| Plasma | 17 (8.6) |
| ICU stay (h), median (range) | 40.0 (21.0–75.0) |
| Readmission to ICU, n (%) | 5 (2.5) |
| Pericardial effusion, n (%) | 5 (2.5) |
| Re-exploration for bleeding, n (%) | 4 (2.0) |
| Perioperative myocardial infarction, n (%) | 3 (1.5) |
| Sternal wound infection, n (%) | 2 (1.0) |
| New-onset atrial fibrillation, n (%) | 31 (15.7) |
| Postoperative ejection fraction (%), mean ± SD | 58.4 ± 7.4 |
| LVEDD (mm), mean ± SD | 47.2 ± 5.3 |
| Operative death, n (%) | 3 (1.5) |
| Cardiogenic | 1 (0.5) |
| Severe pulmonary infection | 1 (0.5) |
| Acute kidney failure | 1 (0.5) |
| Follow-up outcomes | |
| Follow-up (months), median (range) | 34.7 (25.6–53.4) |
| Myocardial infarction, n (%) | 7 (3.5) |
| Stroke, n (%) | 6 (3.0) |
| Ischaemic | 5 (2.5) |
| Haemorrhagic | 10 (0.5) |
| Repeat revascularization, n (%) | 4 (2.0) |
| Death, n (%) | 6 (3.0) |
| Operative death | 3 (1.5) |
| Ischaemic stroke | 1 (0.5) |
| Malignancy | 2 (1.0) |
| MACCE, n (%) | 17 (8.6) |
ICU: intensive care unit; LVEDD: left ventricular end-diastolic diameter; MACCE: major adverse cardiovascular and cerebrovascular event; SD: standard deviation.
Mid-term outcomes
Early postoperative events were included in the analysis of follow-up outcomes. Follow-up was complete for 98.0%, and the median follow-up time was 34.7 (25.6–53.4) months (Table 3). During the follow-up period, 7 (3.5%) patients had myocardial infarctions, and 4 (2.0%) patients underwent repeat revascularization (coronary stenting). Stroke occurred in 6 (3.0%) patients, of which 5 were ischaemic and 1 was haemorrhagic. All-cause death occurred in 6 (3.0%) patients, including 3 (1.5%) operative deaths, 2 (1.0%) deaths of malignancy (liver cancer and oesophageal cancer) and 1 death of ischaemic stroke 1 (0.5%). The cumulative rate of MACCE was 17 (8.6%).
According to the Kaplan–Meier survival analysis, cumulative survival at 1, 3 and 5 years was 98.5%, 98.0% and 95.9%, whereas MACCE-free survival was 98.0%, 93.7% and 89.4% (Fig. 2), respectively. On average, each surgeon performed 7.9 CE operations. Surgeons who performed fewer than 8 CE operations did not show a higher incidence of MACCE compared with those who performed 8 or more procedures (P = 0.341; Supplementary Material, Fig. S1).
Figure 2:
Kaplan–Meier estimates of overall survival (A) and MACCE-free survival (B) according to various uses of cardiopulmonary bypass (C) and performance of LAD endarterectomy (D). CE: coronary endarterectomy; CI: confidence interval; LAD: left anterior descending artery; Pt: patients; MACCE: major adverse cardiovascular and cerebrovascular event.
Subgroup analyses
Baseline characteristics of the subgroups are summarized in Table 4. No difference was observed regarding the incidence of MACCE between open and closed CE (4.5% vs 9.1%; P = 0.473). In addition, the on-pump group showed a trend for a higher incidence of MACCE (Fig. 2C), although with no statistical significance (Plog-rank = 0.256), with the Cox regression showing a similar result [hazard ratio (HR) 2.09, 95% confidence interval (CI) 0.79–5.53; P = 0.139) after adjusting for the body mass index. Similarly, there was no difference in the MACCE occurrence rate (Plog-rank = 0.540) between an LAD and a non-LAD endarterectomy (Fig. 2D). The risk of MACCE remained similar (HR 1.24, 95% CI 0.45–3.46; P = 0.675) after adjustments for variables significantly different between LAD and non-LAD subgroups (i.e. history of percutaneous coronary intervention, triple vessel disease).
Table 4:
Comparison of baseline characteristics between subgroups
| Characteristics | On-pump or off-pump |
Endarterectomy |
||||
|---|---|---|---|---|---|---|
| Off-pump (n = 122) | On-pump (n = 76) | P-value | Non-LAD (n = 110) | LAD (n = 88) | P-value | |
| Age (years), mean ± SD | 60.4 ± 8.9 | 60.0 ± 10.0 | 0.782 | 60.7 ± 9.0 | 59.8 ± 9.8 | 0.482 |
| Male gender, n (%) | 90 (73.8) | 62 (81.6) | 0.206 | 85 (77.3) | 67 (76.1) | 0.851 |
| History of PCI, n (%) | 22 (18.0) | 9 (11.8) | 0.156 | 12 (10.9) | 19 (21.6) | 0.040 |
| Hypertension, n (%) | 81 (66.4) | 51 (67.1) | 0.918 | 73 (66.4) | 59 (67.1) | 0.919 |
| Dyslipidaemia, n (%) | 103 (84.4) | 58 (76.3) | 0.155 | 91 (82.7) | 70 (79.6) | 0.568 |
| Stroke, n (%) | 22 (18.0) | 10 (13.1) | 0.365 | 19 (17.3) | 13 (14.8) | 0.635 |
| Smoking, n (%) | 75 (61.5) | 48 (63.1) | 0.812 | 68 (61.8) | 55 (62.5) | 0.922 |
| Diabetes mellitus, n (%) | 48 (39.3) | 29 (39.2) | 0.868 | 48 (43.6) | 29 (33.0) | 0.126 |
| Prior MI, n (%) | 46 (37.7) | 31 (40.8) | 0.665 | 38 (34.6) | 39 (44.3) | 0.161 |
| PVD, n (%) | 14 (11.5) | 6 (7.9) | 0.416 | 14 (12.7) | 6 (6.8) | 0.170 |
| Body mass index (kg/m2), median (range) | 25.2 (23.5–27.5) | 26.2 (24.6–28.2) | 0.026 | 25.8 (23.7–27.6) | 25.3 (23.7–27.8) | 0.538 |
| NYHA class III or IV, n (%) | 54 (44.3) | 36 (47.4) | 0.669 | 52 (47.3) | 38 (43.2) | 0.566 |
| Triple vessel disease, n (%) | 78 (63.9) | 46 (60.5) | 0.630 | 82 (74.6) | 42 (47.7) | <0.001 |
| Preoperative EF (%), mean ± SD | 59.5 ± 8.3 | 58.9 ± 9.7 | 0.651 | 59.7 ± 8.7 | 58.9 ± 9.0 | 0.517 |
| On-pump, n (%) | 42 (38.2) | 34 (38.6) | 0.948 | |||
| LAD endarterectomy, n (%) | 54 (44.3) | 34 (44.7) | 0.948 | |||
EF: ejection fraction; LAD: left anterior descending artery; MI: myocardial infarction; NYHA: New York Heart Association; PCI: percutaneous coronary intervention; PVD: peripheral vascular disease; SD: standard deviation.
Risk factor analyses
Univariable and multivariable Cox regression analyses were performed to search for possible risk factors for MACCE after CE + CABG. In univariable analysis, baseline characteristics including advanced age, sex, prior myocardial infarction, diabetes mellitus, preoperative NYHA functional class III or IV, triple vessel disease, hypertension, dyslipidaemia and history of percutaneous coronary intervention were analysed. The results indicated that advanced age was associated with an increased risk of MACCE (HR 3.62, 95% CI 1.37–9.62; P = 0.010). Advanced age remained an independent predictor of MACCE (HR 3.59, 95% CI 1.32–9.77; P = 0.013) after adjustment for triple vessel disease and other variables showing a trend for a significant difference (P < 0.2) in univariable analysis, including body mass index and preoperative NYHA classifications (Fig. 3).
Figure 3:
Univariable (A) and multivariable (B) analysis for potential baseline risk factors for major cardiovascular and cerebrovascular events. BMI: body mass index; CI: confidence interval; HR: hazard ratio; MI: myocardial infarction; NYHA: New York Heart Association; PCI: percutaneous coronary intervention.
DISCUSSION
In this retrospective cohort study, we evaluated the feasibility of CE + CABG and analysed potential risk factors for patient outcomes. Our study showed that CE + CABG could be a reliable approach for achieving complete revascularization for diffusely diseased coronary arteries with satisfactory early and mid-term outcomes. In addition, we found that advanced age (>65 years) increased the risk of MACCE, whereas no significant difference was observed between on-pump or off-pump surgery or between LAD and non-LAD endarterectomy.
CE has priority for achieving complete revascularization of diffusely diseased coronary arteries. Although early evidence indicated that CE was associated with poor postoperative outcomes [16, 17], recent studies reported that the short- and long-term outcomes of CE + CABG have improved [8–10]. However, a pooled analysis of these studies [11–13] still showed poor graft patency and higher mortality after CE + CABG. Notably, most of these studies were retrospective and usually had small sample sizes, which could lead to huge variations in patient outcomes. In addition, patients undergoing CE tend to present higher risk profiles at admission (e.g. severely diseased coronary arteries, poor general health conditions) compared with those having CABG alone [13], which could partially account for the poor outcomes after CE [18]. Meanwhile, the heterogeneity between earlier and more recent studies could have led to a biased estimation of the efficacy and safety of CE. The lack of reliable evidence makes it difficult for surgeons to perform CE without safety concerns. Therefore, more evidence is needed to validate the application of CE in clinical practice.
Previously, CE was shown to increase postoperative mortality and complications: Perioperative mortality after CE could be as high as 11% [19]. Another concern is postoperative myocardial infarction [4, 20], with an incidence rate as high as 15% [21]. In this retrospective cohort study of 198 patients, we showed that the operative mortality after CE was 1.5%. Causes of death included intraoperative ventricular fibrillation, severe postoperative pulmonary infection and acute kidney failure. Meanwhile, the incidence of postoperative myocardial infarction was 1.5% as well, which was consistent with results from recent studies. For example, in a cohort of 290 consecutive patients, Wang et al. [22] reported that the perioperative mortality of CE + CABG was as low as 1.4%, whereas the incidence of perioperative myocardial infarction was 0.7%. Furthermore, only 3 patients died during the follow-up period, with 2 cases attributed to late-stage malignancy. In survival analysis, overall survival and MACCE-free survival at 5 years was 95.1% and 88.8%, respectively, showing a favourable mid-term outcome of CE + CABG. Therefore, CE + CABG could be a safe and effective method to achieve complete revascularization in patients with diffusely diseased coronary arteries when performed by experienced, qualified cardiac surgeons.
Although current results indicate that CE + CABG could be performed safely, there are still huge concerns regarding the specific operative strategies, including the use of cardiopulmonary bypass, the performance of the closed CE procedure and the involvement of the LAD [10, 12, 22]. Because we used closed CE techniques, we performed subgroup analyses comparing outcomes of patients on-pump and off-pump and of patients who had LAD and non-LAD endarterectomy.
Off-pump operations are superior to on-pump operations for several reasons. First, off-pump surgery avoids the systemic inflammation caused by cardiopulmonary bypass [23]. Moreover, during off-pump surgery, collaterals might prevent the incidence of myocardial infarction [24]. However, the off-pump strategy might increase the risk of incomplete removal of plaques during CE. Earlier studies have reported similar outcomes regarding on-pump and off-pump strategies for CE + CABG [25, 26]. In our study, patients in the on-pump group showed a trend for lower MACCE-free survival compared with those in the off-pump group, although with no statistical difference. Besides the advantages just mentioned, one possible interpretation could be that patients who had off-pump surgery received fewer perioperative transfusions and had shorter stays in the intensive care unit compared to patients in the on-pump group.
The impact of the CE site on clinical outcomes after CE + CABG is still controversial. Minale et al. [27] reported in an observational study that LAD endarterectomy was associated with an increased risk of perioperative myocardial infarction. However, Qiu et al. and Nardi et al. [10, 28] showed in more recent studies that LAD endarterectomy has a favourable outcome, whereas others supported the view that the site of CE had no obvious impact on follow-up outcomes [22]. In our study, we showed that there was no significant difference between the subgroups of LAD and non-LAD endarterectomies despite multiple adjustments. Based on these findings, the site of CE had little impact on the outcomes of patients undergoing CE + CABG.
For cardiac surgeons, it is of great interest and importance to identify potential risk factors for patients having CE + CABG, including specific demographics and clinical presentations. In a recent meta-analysis, Wang et al. [12] suggested that, compared with those receiving CABG alone, patients undergoing CE + CABG more frequently have preoperative comorbidities, such as diabetes mellitus, hypertension, prior myocardial infarction, peripheral vascular disease and renal failure. We performed univariable analysis and multivariate analysis to explore the possible risk factors. The results indicated that advanced age was associated with a higher risk of MACCE. Therefore, patients with advanced age should be carefully assessed before the operation.
Limitations
Our study has several limitations. First, it was a single-centre, retrospective cohort study, with no control group of patients receiving CABG or conservative medical treatment. Potential confounding could still exist even after the multiple adjustments for various risk factors. Moreover, the sample size and number of events were not large enough for a complete multivariable analysis, which might affect the power of the tests. Consequently, prospective studies with larger sample sizes are needed to further validate the current results.
CONCLUSIONS
Overall, CE + CABG could be an acceptable way to achieve complete revascularization with satisfactory outcomes when performed by experienced, qualified surgeons. Advanced age may increase the risk of MACCE. The mid-term outcomes were comparable between patients undergoing on-pump and off-pump surgery as well as those having LAD endarterectomy and non-LAD endarterectomy.
SUPPLEMENTARY MATERIAL
Supplementary material is available at ICVTS online.
Funding
This work was supported by the National Key Research and Development Program [2018YFC1311201] from the Ministry of Science and Technology of the People's Republic of China.
Conflict of interest: none declared.
Author contributions
Xieraili Tiemuerniyazi: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Writing—original draft. Hua Yan: Data curation; Investigation; Project administration; Writing—review & editing. Yangwu Song: Data curation; Formal analysis; Investigation. Yifeng Nan: Data curation; Investigation; Methodology. Fei Xu: Conceptualization; Formal analysis; Methodology; Project administration; Supervision; Writing—review & editing. Wei Feng: Data curation; Formal analysis; Methodology; Project administration; Resources; Supervision; Validation; Writing—review & editing.
Reviewer information
Interactive CardioVascular and Thoracic Surgery thanks Husam Balkhy, Ikuo Fukuda and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.
Supplementary Material
Abbreviations
- CABG
Coronary artery bypass grafting
- CE
Coronary endarterectomy
- CI
Confidence interval
- HR
Hazard ratio
- LAD
Left anterior descending artery
- MACCE
Major adverse cardiovascular and cerebrovascular event
- NYHA
New York Heart Association
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