For patients with prior coronary artery bypass grafting and recurrent myocardial ischemia, percutaneous coronary intervention on bypass graft or native coronary artery?—A 5‐year follow‐up cohort study

Abstract Background Real‐world data on target vessel of percutaneous coronary intervention (PCI) for patients with prior coronary artery bypass grafting (CABG) was still limited. Hypothesis A prospective cohort was examined to determine the frequency and outcomes of native coronary artery PCI versus bypass graft PCI in patients with prior CABG. Methods A large‐sample observational study enrolled a total of 10 724 patients with coronary artery disease (CAD) underwent PCI in 2013. Two‐ and five‐year clinical outcomes were compared between graft PCI group and native artery PCI group in patients with prior CABG. Results A total of 438 cases had CABG history in the total cohort. Graft PCI group and native artery PCI group accounted for 13.7% and 86.3%, respectively. The rates of 2‐ and 5‐year all‐cause death and major adverse cardiovascular and cerebral events (MACCE) showed no significant difference between the two groups (p > .05). Two‐year revascularization risk was lower in graft PCI group than native artery PCI group (3.3% and 12.4%, p < .05), but 5‐year myocardial infarction (MI) risk was higher (13.3% and 5.0%, p < .05). In multivariate COX regression models, graft PCI group was independently associated with lower 2‐year revascularization risk (hazard ratio [HR]: 0.21; 95% confidence interval [CI]: 0.05–0.88; p = .033), but higher 5‐year MI risk than native artery PCI group (HR: 2.61; 95% CI: 1.03–6.57; p = .042). Five‐year all‐cause death and MACCE risk showed no difference between the two groups in model. Conclusions In patients with prior CABG underwent PCI, patients in graft PCI group had higher 5‐year MI risk than patients received native artery PCI. But, 5‐year mortality and MACCE was not significantly different between graft PCI group and native artery PCI group.

all-cause death and MACCE risk showed no difference between the two groups in model.

Conclusions:
In patients with prior CABG underwent PCI, patients in graft PCI group had higher 5-year MI risk than patients received native artery PCI. But, 5-year mortality and MACCE was not significantly different between graft PCI group and native artery PCI group.
coronary artery bypass grafting, coronary artery disease, percutaneous coronary intervention

| INTRODUCTION
Coronary artery bypass grafting (CABG) has been applicated for more than 50 years in patients with severe coronary artery disease (CAD). 1 In patients with prior CABG, atherosclerosis might progress, with newly occurred stenosis or occlusion in the graft. [2][3][4] And patients with chronic bypass graft lesions often present with recurrent angina pectoris, myocardial infarction (MI), even sudden death. The strategy and technique of revascularization for this special population remained a difficult problem in the interventional treatment area of CAD. Simple optimization of drug therapy often cannot control myocardial ischemia in such patients. However, secondary thoracotomy for re-CABG is supposed not the first choice due to anatomical changes, tissue adhesions, and the source of bridging vessels. Therefore, percutaneous coronary intervention (PCI) has become the first choice of treatment strategy for recurrent myocardial ischemia after CABG. [5][6][7][8] It is widely believed that native coronary arteries should be the preferred target vessel of PCI in patients with prior CABG, if technically feasible, because native coronary artery PCI appears to be associated with better short-and long-term outcomes compared with bypass graft PCI. 9,10 However, patients with prior CABG and recurrent myocardial ischemia tend to be elderly, with severe myocardial ischemia, poor cardiac function, and many comorbidities, there is a lack of randomized controlled trials (RCT) or large sample retrospective data for comparison of efficacy and safety between native artery intervention and graft intervention. [11][12][13] Clinical practice still emphasizes the principle of individualization. Moreover, with widespread use of the secondgeneration drug-eluting stents and development of drug therapy, including stronger P2Y12 receptor antagonists and anti-reflow medication, the risk of graft intervention has been reduced. 14 In the present situation, how to select target vessels in patients with prior CABG also requires new data.
Therefore, we examined a large-sample all-comer observational cohort, to compare the outcomes of patients with CABG history who received PCI on native arteries and graft arteries due to recurrent myocardial ischemia, aimed to provide some realworld data for optimization of target vessel selection in patients with prior CABG.

| Procedural details
Before elective PCI, if not taking long-term aspirin and clopidogrel, patients received aspirin and P2Y12 inhibitor with loading dose orally. Patients with acute coronary syndrome scheduled for primary PCI received the same dose of aspirin and clopidogrel (loading dose 300 or 600 mg, according to bleeding risk) as soon as possible.
Before coronary angiography (CAG), 25 mg heparin sodium was administered through an arterial sheath or intravenously. Before PCI, 100 U/kg of heparin sodium was administered. The dose was lowered to 50-70 U/kg in patients over the age of 70 to reduce bleeding risk. If PCI proceeded for more than 1 h, an additional 1000 U of heparin sodium was administered. Results of CAG were read by experienced cardiologists. More than 50% stenosis of left main artery (LM), left anterior descending artery (LAD), left circumflex artery (LCX), right coronary artery (RCA), and main branch of these vessels was defined as coronary artery stenosis. More than 70% stenosis of the vessels mentioned above, along with ischemic LIU ET AL. | 681 symptoms or ischemic evidence showed by examinations, was indicated for coronary stent implantation. Three-vessel disease (TVD) was defined as angiographic stenosis of ≥50% in all three main coronary arteries, LAD, LCX, and RCA.

| Follow-up and definitions
The patients were visited 30 days and 6 months after PCI and every 1 year thereafter. Information of in-hospital outcome was obtained through review of medical records, and the long-term clinical outcome was collected from survey completed by telephone

| 2-and 5-year clinical outcomes
For the analyzed population, clinical follow-up was completed for all patients. The occurrence of adverse cardiovascular and cerebrovascular events in each group is listed in However, when optimal medication cannot able to control the symptoms of myocardial ischemia well, patients are re-admitted and resorted to revascularization. And as a compromise, they receive T A B L E 3 2-and 5-year outcomes. partial revascularization by PCI to achieve some improvement in quality of life, even cardiac function. The progress of PCI technology and equipment plays a key role. It was reported that patients undergoing redo CABG were more complex and associated with worse clinical outcomes than those receiving PCI. 21 The absolute survival benefit of successful CTO procedures was more pronounced in patients with previous CABG than in non-CABG patients. 22 Therefore, PCI gradually become the first choice on the basis of "technical" feasibility in patients with prior CABG and recurrent myocardial ischemia. 23 In this study, 87.4% of the patients had LAD lesions, and most of the lesions were type B2 or C. Only 7.5% of the patients had LM involved or TVD, lower than expected. Since the population we analyzed in this study was all patients with recurrent myocardial ischemia after CABG undergoing PCI, it is conceivable that they were patients who still had the opportunity for intervention. Patients who did not have the opportunity for intervention and chose to take medicine were not included in the analysis. Diabetes was present in 35.6% of patients with prior CABG in this study. These real-world data reflected that treatment situation was reasonable and guidelinefollowed. CABG was found superior to PCI in patients with multivessel disease and diabetes. 23  contributed to stent thrombosis and recurrent MI to some extent.
Second, the application of endovascular imaging, optical coherence tomography and intravascular ultrasound, was relatively low in this cohort study in 2013. Nevertheless, this is a core laboratory analysis comparing the efficacy and safety between bypass graft PCI and native coronary artery PCI in patients with prior CABG and recurrent myocardial ischemia, in terms of both long-term outcomes and angiographic data, and we believe that we have accounted for the most clinically relevant variables in our model.

| CONCLUSIONS
In patients with prior CABG and recurrent myocardial ischemia undergoing PCI, compared with patients who received native artery PCI, those who received graft PCI had lower 2-year revascularization risk, but higher 5-year MI risk. However, 5-year all-cause death and MACCE were similar between graft PCI group and native artery PCI group.

AUTHOR CONTRIBUTIONS
Ru Liu contributed to all aspects of this study, including study concept and design, data acquisition, statistical analysis and interpretation, drafting and revising the report, and funding. Haibo Yuan contributed to initial study conception and design, and funding.