Introduction
Chronic kidney disease (CKD) generally has a worse prognosis after invasive procedures such as PCI or CABG than patients with healthy renal function. Coronary artery disease (CAD) is the main factor of death induced by cardiovascular events in CKD study participation [
1]. CAD patients with CKD have serious and complex coronary artery lesions, resulting in a poor prognosis and a large economic burden on patients [
2]. A study conducted by Baber et al. [
3] concluded that the risk of mortality, major adverse cardiovascular and cerebrovascular events (MACCEs), myocardial infarction (MI), as well as stroke is significantly higher in study participants with CKD compared with those without CKD. In a study of left main artery remodeling by Giustino et al. [
4], mortality and incidences of major adverse cardiovascular events were significantly higher in CAD study participants with CKD than in CAD patients without CKD. Therefore, we should pay more attention to how to find more effective cardiac treatment strategies for these patients.
Recent studies have revealed that for CAD patients with CKD, timely diagnosis and early PCI or CABG have a lower mortality rate than drug therapy [
5,
6]. Previous research has discovered that although CABG increases the incidence of short-term acute kidney injury, patients who underwent CABG have more favorable survival outcomes than those who underwent PCI [
7,
8]. However, Kang et al. [
9] conducted follow-up research including 2,108 CKD study participants with multi-vessel CAD, which concluded PCI utilizing drug-eluting stents had similar composite outcomes for stroke, all-cause death, or myocardial infarction (MI) compared with CABG group.
The 2018 European Society of Cardiology/ European Association for Cardio-Thoracic Surgery (ESC/EACTS) Guidelines recommend CABG over PCI in patients with moderate to severe CKD with multi-vessel disease [
10]. Similarly, the American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend that CABG is superior to PCI in patients with end-stage renal disease (ESRD) accompanied by three-vessel disease, proximal left anterior descending artery (LAD) disease, plus other major artery disease [
11]. However, these guidelines recommend mostly based on observational studies comparing bypass surgery with first-generation drug-coated stents or bare metal stents [
12]. Results of an observational study by Bangalore et al. [
13] show that in patients with CKD who underwent coronary revascularization, bioabsorbable polymer-coated platinum chromium everolimus-eluting stent (BP-EES), compared to those who underwent CABG surgery, were less frequent need for repeated revascularization and of significantly lower risk of death and stroke at one month. Thus, there is still a controversy as to whether CABG or PCI is better for patients with CKD combined with CAD. Therefore, we implemented a meta-analysis of randomized controlled trials (RCTs) that had already been published to select a more appropriate treatment for CKD patients with CAD.
Discussion
The purpose of our research is to conduct a meta-analysis to compare the long-term and short-term outcomes of CKD patients receiving invasive treatment, including CABG and PCI. Eventually, five relevant RCTs were published [
4,
8,
18‐
20]. Our results show that CABG in CKD patients is associated with a lower risk of long-term MACCEs, cardiac death, long-term repeated revascularization, and cerebrovascular accident compared with PCI. However, the long-term recurrence rate of MI was similar in the participants who underwent CABG and PCI cohorts. Interestingly, there were no significant differences in short-term risk of all-cause death, MACCE and repeated revascularization among the participants with who underwent CABG and PCI.
A previous meta-analysis of 2 trials and 15 retrospective trials (including 62,343 CKD patients) reported that compared with PCI, CABG is associated with lower long-term mortality, MI, and repeated revascularization risk, and these results are consistent with our meta-analysis [
21]. The heterogeneity of MACCEs’ RR in our results is significantly high, possibly resulting from the defect of the design of the experimental process as well as the different features in the eligibility criteria of inclusion and exclusion between research. PCI usually treats the culprit vascular disease that causes obvious symptoms. Nevertheless, other residual vascular stenoses will redevelop after undergoing PCI operation, inducing revascularization development to be incomplete. The growing risk of incomplete revascularization is regarded as the primary factor of adverse cardiovascular events, including MI, repeated revascularization, as well as cardiac death [
22]. On the contrary, participants undergoing CABG can be provided with new blood vessels to substitute the culprit blood vessels, which ensures a greater possibility of achieving revascularization completely than participants undergoing PCI. Moreover, because of the requirement for repeated revascularization, CKD patients receiving PCI undergo routine coronary angiography follow-up more frequently than patients receiving CABG, and coronary angiography also increases the incidence of adverse events to a certain extent [
23]. Recent research has revealed that the incidence of stroke in the participants who underwent CABG may be reduced because of the utilization of the off-pump surgery technique as well as the avoidable utilization of aortic clipping [
13]. Even though the long-term events of participants undergoing PCI are not as favorable as participants undergoing CABG, PCI still has advantages over CABG, including a lower incidence of infection, shorter discharge time, and faster recovery.
Our study found that PCI was significantly less effective than CABG in terms of repeated revascularization and cardiovascular mortality endpoints. Several possible reasons can be analyzed: (1) CKD is often secondary to diabetes [
24,
25], and diabetes can significantly increase the risk of in-stent restenosis in CAD patients after PCI, leading to a more frequent need for repeated revascularization. (2) CAD combined with CKD often manifests as diffuse multi-vessel lesions [
26]. For these patients, PCI is generally difficult to achieve complete revascularization, with limited improvement in myocardial ischemia and increased risk of angina recurrence. (3) CKD patients often have severe calcification, occlusion, and complex lesions. Much more contrast agent is needed during PCI, and combined with renal dysfunction and a high rate of diabetes, the risk of contrast-induced nephropathy is dramatically increased [
27], further exacerbating the condition. All the above reasons would lead to more cardiovascular events such as repeated revascularization and cardiac mortality after PCI. The 2018 ESC/EACTS Guidelines on myocardial revascularization recommended CABG for stable angina patients with three-vessel disease and diabetes (Class IA recommendation). Our research conclusions are aligned with this guideline recommendation [
10].
A meta-analysis that included 2 RCTs and 15 retrospective experiments reported that contrary to our findings, the incidence of short-term all-cause death of CABG is higher than PCI [
21]. At the same time, it is interesting that a summary analysis of two RCTs with short-term MACCEs and repeated revascularization outcomes found that the risk of MACCEs and the proportion of patient participants who underwent PCI who require repeated revascularization were significantly reduced than participants who underwent CABG. Therefore, further research is required to explore whether CKD participants with CAD who undergo PCI or CABG have similar short-term risks.
Limitations
The novelty of this study is that we included all randomized controlled experiments. However, our research has several restrictions. Firstly, the amount of people participating in the research is still limited. Secondly, the SYNTAX scale tool is a specific instrument introduced by the Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery (SYNTAX) trial, which was utilized to assess the severity as well as the progression of CAD. Because of the lack of SYNTAX scale data in the majority of the research involved, the analysis of subgroups according to different SYNTAX score ranges were unfinished. Thirdly, a previous study has shown that patients undergoing peritoneal dialysis have a decreased incidence of hemorrhagic stroke than patients undergoing hemodialysis [
28]. Nevertheless, an analysis of subgroups according to different dialysis types (peritoneal dialysis and hemodialysis) couldn’t be implemented because the involved research did not offer enough information on dialysis types. Fourth, many included studies did not evaluate drug therapy, which may affect long-term results. What’s more, our study was the lack of evaluation of patients with renal dysfunction categorized according to eGFR due to the subgroup analyses were not being performed in the five included research. Last but not least, our study obtained a limited sample with a total of 1198 patients, conclusion needs to be further studied in a larger population.
Conclusion
Thus, in accordance with the long-term follow-up results, CABG is still better than PCI for CAD patients with CKD. However, further large-sample RCT experiments are still needed to confirm the short-term MACCEs risk of PCI and CABG.
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