Some patients with Stanford type A aortic dissection (STAAD) may have coronary artery problems, such as coronary artery involvement or coronary atherosclerotic heart disease (1–3). In addition, some patients with myocardial ischaemia or even myocardial infarction show significantly increased early mortality (3, 4). For patients with type C or some type B based on Nari's classification, coronary artery bypass grafting (CABG) is needed to improve coronary malperfusion (3).

Due to its urgency, the great saphenous vein graft (SVG) is the main graft for CABG in STAAD because of its convenience and rapid access (5). At present, there are two main types of proximal artery bypass grafts after ascending and total aortic arch replacement: SVG to artificial aortic bypass (SVG-AO) or SVG to non-aortic bypass (SVG-non-AO). Which type is chosen is mainly according to the personal experience of surgeons. To prevent the artificial aorta from oozing blood, some doctors will wrap the aorta and implement a modified Cabrol fistula technique (6–9). However, as it is difficult to bypass SVG to the proximal aorta after wrapping, the secondary artery is used for proximal artery bypass grafting in most patients with STAAD concomitant with CABG (SVG-non-AO). Overall, some doctors suggest that the rate of resurgery has become lower with the improvement of meticulous care and precise techniques and the effect of wrapping the aorta and the modified Cabrol fistula technique may not be significant (10, 11); thus, bypass can be performed on the artificial aorta without wrapping the aorta. Nevertheless, the prognosis of patients undergoing these two approaches is unclear. Indeed, both may have adverse effects on grafts. On the one hand, the aortic wall of the artificial artery is more rigid than the normal aorta, which may lead to problems related to the proximal anastomosis of the SVG. On the other hand, the non-aorta (brachiocephalic trunk, left common carotid artery, and left subclavian artery) flow is lower than that in the aorta, and low flow is associated with graft occlusion (12).

Therefore, our study aimed to clarify the early- and mid-term prognosis of these two groups of patients and to provide a reference for the choice of the location of the proximal end of the graft in STAAD concomitant with CABG.

Aortic dissection is sometimes accompanied by coronary artery problems (13, 14). Although some serious coronary artery problems require CABG during surgery, there is some controversy regarding the location of the proximal end of the bypass. For type A aortic dissection, the ascending aorta will be replaced with an artificial aorta. However, as the patency of SVG bypass to the artificial aorta is not clear, some doctors choose a secondary artery, such as the left subclavian artery, as the location of the proximal bypass. Our study compared early- and mid-term results between these two groups. We found no significant difference in terms of the early patency of the graft or early outcomes. Nevertheless, SVG bypass to the secondary artery did have poor graft patency in the mid-term (3 months and 1 year) compared to SVG bypass to an artificial aorta. There were no aortic-related events in either group at the 1-year follow-up.

The STAAD with concomitant CABG is associated with high operative mortality (15, 16), in accordance with our study (32.3% early mortality in all CABG patients in our study). CABG is recommended for some patients with serious previous coronary artery disease or coronary artery involvement with type B or type C according to Neri's classification (3, 17), though this situation will have some problems. On the one hand, some patients have severe myocardial ischaemia or even myocardial infarction before surgery, and early coronary reperfusion is necessary. There is also a risk of sudden rupture of the aorta. The contradiction between them (priority coronary reperfusion and aortic dissection) may be one of the main reasons. Aortic dissection is sometimes accompanied by coronary artery problems (13, 14). Although some serious coronary artery problems require CABG during surgery, there is some controversy regarding the location of the proximal end of the bypass. For type A aortic dissection, the ascending aorta will be replaced with an artificial aorta. However, as the patency of SVG bypass to the artificial aorta is not clear, some doctors choose a secondary artery, such as the left subclavian artery, as the location of the proximal bypass. Our study compared early- and mid-term results between these two groups. We found no significant difference in terms of the early patency of the graft or early outcomes. Nevertheless, SVG bypass to the secondary artery did have poor graft patency in the mid-term (3 months and 1 year) compared to SVG bypass to an artificial aorta. There were no aortic-related events in either group at the 1-year follow-up.

The STAAD with concomitant CABG is associated with high early mortality. A small number of patients received priority CABG or distal retrograde perfusion of cardioplegia. Due to ascending aortic dissection, the proximal bypass location of the SVG can only use the secondary artery without dissection. On the other hand, Zhang et al. (9) reported that wrapping the aorta and presenting a modified Cabrol fistula technique can significantly reduce post-operative bleeding in STAAD. Nonetheless, proximal aortic bypass after this method is difficult, and some doctors choose a secondary artery for SVG proximal bypass. In our study, there was no significant difference in 24-h drainage volume between the two groups. The reason may be that in the aortic bypass group, aorta wrapping shunts and sandwich sutures of artificial vessel patch SVGs were used for some patients. With regard to early results, there was no significant difference in our study between different proximal bypass methods for early death and bleeding.

The patients with CABG were followed up for 1 week, 3 months, and 1 year. At 3 months and 1 year, the graft failure of SVG-non-AO was significantly higher than that of SVG-AO, and the latter was an independent protective factor for 1-year graft patency. We consider the main reason to be the fact that the aortic flow is higher than that of a secondary artery, indirectly increasing the flow of grafts. In addition, the angle of the anastomosis may affect the coronary circulation (18), and blood flow of 70 to 90° was highest. The angle of the aorta may be closer to the best angle, though the angle of the secondary artery may not. In addition, some reports show that the use of double antiplatelets and statins after surgery is beneficial for vein graft patency (19, 20). However, there was no significant difference in post-operative antiplatelet and statin levels between the groups. Post-operative double antiplatelet therapy was a protective factor for 1-year graft patency; some patients with STAAD have a residual dissection of the abdominal aorta, and dual antiplatelet therapy may increase the risk of aortic-related events. The number of patients using dual antiplatelet therapy in our study was 13. Except for two patients with oral mucosal hemorrhage and one patient with cerebral hemorrhage, there were no aortic-related events, but larger sample size is needed for verification. In addition, there was no significant difference in coronary heart disease-related symptoms between the two groups at the 1-year follow-up, which may be due to the formation of collateral circulation. In conclusion, our mid-term results suggest that SVG-AO should be the first choice of proximal bypass location for patients with STAAD and bypass grafts and that dual antiplatelet therapy should be used as much as possible after surgery if there is no risk of bleeding. These 62 patients did not undergo coronary angiography before the operation because the situation was urgent and a coronary angiogram might aggravate dissection. After surgery, most patients did not have symptoms of coronary ischemia, there were only seven patients (18.9%) who had symptoms of coronary artery disease. In these patients, only two patients received coronary angiograms. Both patients belonged to the SVG-non-AO group, and the angiographic results showed that the grafts were occluded.

Our study also has some limitations. First, at baseline, the time from symptom onset to surgery and previous coronary artery disease was significantly different between the two groups, which may be due to the selection bias of retrospective studies. Second, because STAAD cases with CABG are very rare, our sample size was relatively small, which may have caused some bias. Although coronary artery angiography is the gold standard to evaluate the coronary artery, it is an invasive examination, and there may be a risk of aortic adverse events with coronary angiography in some patients with residual abdominal aortic dissection. Therefore, we used coronary computed tomography angiography to evaluate the graft, which may lead to inaccurate evaluation of some coronary stenoses.

The raw data supporting the conclusions of this article will be made available by the authors with the consent of the authors.

The studies involving human participants were reviewed and approved by the Anzhen Hospital Ethics Committee. Written informed consent was not required for this study, in accordance with the local legislation and institutional requirements.

HZ and MW designed the whole conception. HZ, MG, and LS provided the administrative support. MW, SJ, and MG provided the data of patients. MW, SJ, and XP collected and assembled the data. MW was a major contributor in writing the manuscript. All authors have read and approved the final manuscript.

This study was supported by the National Key R&D Program of China (2017YFC1308000), the National Science Foundation of China (81770466), and the Beijing Municipal Administration of Hospital's Ascent Plan (DFL20180602).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.