An epidemiological survey in 2012 indicated that the incidence of CKD in China was 10.8%, and that the estimated number of existing CKD patients was 119.5 million . The risk of coronary heart disease is significantly increased in patients with CKD. Inflammatory reactions, oxidative stress, impaired endothelial cell function, coronary artery calcification, hyperhomocysteinemia, immune suppression, and other mechanisms participate in accelerating the progression of atherosclerosis, which leads to a poor prognosis in this population. Coronary heart disease-related complications, including myocardial infarction and heart failure, are the main causes of death . For patients with advanced CKD and dialysis dependence, mortality related to coronary heart disease ranges from 40–50%. In patients with CKD, lipid metabolism disorders, mainly hypertriglyceridemia, are risk factors for complications related to coronary heart disease. This risk factor results in approximately 12% of people with stage 3 or more advanced CKD also having coronary heart disease, compared with 5% of people with normal renal function. Patients with CKD also often have associated bone mineral metabolism disorders such as hypocalcemia and hyperphosphatemia, as well as secondary hyperparathyroidism, which also accelerate systemic atherosclerosis and vascular calcification.Currently, the number of patients with CKD in mainland China is very high, and many more patients with coronary heart disease will require CABG in the future.
For patients with CKD with severe coronary heart disease and not receiving dialysis, CABG significantly reduces mortality, reinfarction, and revascularization rates compared with PCI and drug therapy [11, 12]. For low-risk patients, CABG does not improve survival compared with PCI and oral medications, but significantly improves survival for high-risk patients, although increases the incidence of postoperative renal failure . In a nonrandomized study prospectively analyzing patients’ data, 2108 patients with CKD and with drug-eluting stents underwent PCI (n = 1165) and CABG (n = 943), with a mean follow-up of 41.4 months. Although there were no significant differences in all-cause death, stroke, or myocardial infarction rates between the two groups, the revascularization rate was significantly higher in the PCI group (adjusted hazard ratio: 4.72; 95% CI: 3.20–6.96; p < 0.001) . A meta-analysis of 29,246 patients enrolled in 11 studies showed that CABG was associated with lower long-term all-cause mortality, lower cardiac mortality, lower incidence of myocardial infarction and revascularization, and fewer major cardiac and cerebrovascular adverse events compared with drug-eluting stents in revascularization for coronary heart disease in patients with multivessel disease and CKD. For patients with type 2 diabetes, CKD and stable coronary heart disease, CABG and optimal drug therapy did not reduce the incidence of major cardiac and cerebrovascular adverse events, but significantly reduced the proportion of patients requiring revascularization . Therefore, CABG has a significant advantage over PCI and drug therapy in patients with coronary heart disease and CKD.
CABG is the key to protecting renal function and improving postoperative survival rates in patients with CKD; however, whether to select off-pump or on-pump CABG is controversial. According to current research, off-pump CABG may have more advantages because it has a protective effect on renal function perioperatively in avoiding cardiopulmonary bypass, and reduces complications related to allogeneic blood transfusion, postoperative thoracotomy hemostasis, acute kidney injury, and respiratory problems . However, in CORONARY study, no significant difference in the effect of the two surgical procedures was seen regarding renal function at the 1-year follow-up, and off-pump CABG had no long-term renal protective effect . Ueki et al. reviewed data from 38051 patients undergoing CABG alone and assigned patients to separate groups according to renal function. The results showed that in the mild renal insufficiency group, there was no significant reduction in the risk of death from off-pump CABG compared with the on-pump CABG group. In the moderate to severe renal insufficiency group, compared with on-pump CABG, off-pump CABG significantly reduced surgical mortality and the risk of requiring postoperative dialysis, in patients with severe renal insufficiency .
Off-pump CABG is the main surgical method in our department. In this study, patients with CKD were mainly older women, and more often complicated with hypertension, diabetes, stroke, atrial fibrillation, hypoproteinemia, anemia, and lower LVEF. Postoperative 30-day mortality (p < 0.001) and complications in the CKD group were significantly higher than in the normal group in our study. Logistic regression analysis showed that preoperative CKD increased postoperative complications (AKI, gastrointestinal bleeding, new atrial fibrillation, secondary tracheal intubation, stroke, LCOS, perioperative use of IABP, chest wound infection, prolonged mechanical ventilation, prolonged ICU stay, prolonged length of stay, dialysis replacement, and postoperative 30-day mortality. After correcting for sex, age, and LVEF, preoperative CKD remained a risk factor for the following complications: AKI, gastrointestinal bleeding, secondary endotracheal intubation, stroke, chest wound infection, prolonged ICU stay, prolonged length of stay, dialysis replacement, and postoperative death within 30 days. Therefore, even with off-pump CABG, postoperative complications and 30-day mortality in patients with CKD remained significantly higher than in those with normal renal function.
Preoperative CKD and worse renal function is associated with increased hospital stay and costs. Creatinine clearance rates decreasing from 80 mL/min to 60 mL/min, 40 mL/min, and 20 mL/min result in total hospital expenses increasing by 10%, 20%, and 30%, respectively; the incidence and mortality related to dialysis also increases . Therefore, it is necessary to strengthen perioperative management and develop comprehensive strategies for high-risk patients, to improve prognosis and reduce complications and mortality. We suggest: ① Preoperative assessment of high-risk patients with CKD is conducive to rational allocation of medical resources and targeted prevention and management. More severe preoperative CKD is associated with higher surgical mortality. A retrospective analysis of 483914 patients undergoing CABG alone showed that the operative mortality was 1.3% in patients with normal renal function and increased to 9.3% in those with severe renal insufficiency (GFR < 30 mL/min/1.73 m2) not on dialysis . Conversely, for every 10 mL/min/1.73 m2 increase in eGFR, the risk of death decreases by 20%. The use of the CKD-EPI equation to calculate eGFR for grouping patients according to CKD severity is also a good predictor of postoperative complications and mortality . Charytan et al. suggested that factors such as repeat cardiac surgery, stroke, cardiogenic shock, emergency surgery, and composite valve surgery should be included in the preoperative risk assessment to identify high-risk patients for surgery; however,the specificity and sensitivity of these factors require verification . ②Active control of complications, such as controlling hypertension, correcting anemia, and rational treatment of peripheral artery disease is important. Patients with CKD have a high incidence of hypertension, which may lead to or result from CKD. Hypertension aggravates CKD, which thenincreases the difficulty of controlling hypertension . Anemia is also a common manifestation with renal insufficiency. Renal dysfunction leads to decreased erythropoietin secretion and anemia. Both anemia and CKD can predict myocardial ischemia in patients with coronary heart disease; the severity of the anemia is associated with the degree of myocardial ischemia. Furthermore, anemia is an independent risk factor for increased mortality in patients with coronary heart disease with hemoglobin levels < 12 g/dl [26, 27]. ③New targeted drug therapies such as small-dose human atrial natriuretic peptide injections perioperatively during on-pump CABG can improve perioperative cardiac renal function and reduce the incidence of cardiac events and new dialysis requirement . However, the role of human atrial natriuretic peptide injections in off-pump CABG must be verified.