Short- and mid-term outcomes of the aortic root repair versus root replacement in acute type A aortic dissection

Introduction

Acute type A aortic dissection (ATAAD) is a life-threatening, catastrophic disease with an estimated incidence of 2.9 cases per 100,000 people per year (1). Aortic dissection has the highest mortality rate within 48 h after symptom onset and requires urgent surgical treatment. ATAAD lesions often manifest with extensive root involvement, resulting in varying degrees of aortic insufficiency (AI), coronary artery involvement, and destruction of the inherent structure of the aortic root.

The treatment principle for the aortic root is restoration of a well-functioning aortic valve, obliteration of the false lumen, and resolution of the coronary malperfusion (2). The ongoing debate centers on determining the optimal that achieves maximum benefits while minimizing associated risks.

Although aortic root replacement (the Bentall procedure) is a standard operation that greatly avoids the risk of secondary surgery (2), patients face the burden of lifelong anticoagulation, risk of bleeding and thrombosis after using mechanical valves, and risk of valve-associated dissection and structural valve degradation caused by biological valves. Therefore, aortic root repair surgery that preserves the valve and reconstructs the anatomical structure of the root is recommended.

Owing to differences in the indications and surgical methods of root repair in different institutions, inconsistent results have been published regarding the long-term durability of root repair (3,4).

This study aimed to compare the early- and mid-term clinical outcomes of root replacement and repair, aiming to consolidate experiences in root surgery and provide clinical evidence for future selection of surgical procedures. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-56/rc).

Methods

Study design

From December 2018 to December 2021, 442 patients with ATAAD (352 males and 90 females) underwent Bentall procedure or aortic root repair (modified sandwich technique) at The First Affiliated Hospital of The Air Force Military Medical University. They were diagnosed using computed tomography angiography. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This retrospective study was approved by the Ethics Committee of The First Affiliated Hospital of The Air Force Medical University (No. 20120216-4) and informed consent was taken from all the patients.

Indications

Among the 442 ATAAD patients, 227 were included in the repair group (RG) and 215 in the Bentall group (BG). The indications for aortic root replacement were patients with aortic root sinus diameter of ≥4.5 cm, severe sinotubular junction involvement, unrepairable aortic valvulopathy, severe coronary ostium involvement, connective tissue disease, intimal tear at the aortic root or dissection involving three aortic sinuses; the remaining patients underwent aortic root repair.

Outcomes

Early results were determined based on in-hospital/30-day clinical results. All patients were followed up and evaluated at 1, 3, 6, and 12 months after discharge and annually after that. Postoperative clinical data were obtained through outpatient examinations and telephone interviews. The baseline data, perioperative outcomes, all-cause mortality, and proximal reoperation rates were compared between the two groups.

Operative techniques

Our previous studies introduced details of cerebral perfusion and extracorporeal circulation (5,6). The Bentall procedure was performed using artificial blood vessels combined with biomechanical valves in a standard manner. Aortic root repair surgery was performed using a modified sandwich operation. A transverse incision was made above the junction of the aortic sinus tube to sever the aorta, and the thrombus in the proximal end of the junction of the aortic sinus tube was completely removed. After exploring the extent of dissection of the aortic sinus, the Teflon felt was cut to a matching size according to the condition of the dissection involving the aortic sinus, and was placed in the false lumen of the proximal aortic dissection. A vascular graft and autologous pericardium were placed inside and outside the aorta at the sinus tube junction. Two circles were continuously sutured using 5-0 prolene suture for fixation and reinforcement, then intermittent suture was performed with 4-0 prolene on the outer wall of the aorta involved in the dissection. For patients with severe aortic sinus tear, three suspension stitches were passed through the commissure head (using a 5-0 prolene) and suspended. The vascular graft was then everted, and end-to-end anastomosis was performed with the distal graft (Figure 1). The standard method for aortic arch repair is total arch replacement combined with stented elephant trunk implantation (7). Coronary artery bypass grafting (CABG) was performed using the great saphenous vein, indications for CABG included: previous bypass graft occlusion, aortic dissection extending to the coronary ostium, coronary artery disease or severe coronary artery calcification. Some patients underwent repairs for foramen ovale, mitral valve, and tricuspid valve. Cerebral oxygenation in the frontal cortex and the identification of potential cerebral hypoperfusion were monitored using near-infrared spectroscopy. The cerebral perfusion pressure was maintained at 60–70 mmHg; the cerebral perfusion flow was approximately 5–10 mL/(kg·min).

Figure 1 Aortic root repair (sandwich surgery) schematic diagram. The Teflon felt is represented by yellow; the vascular graft and autologous pericardium are represented by gray and red, respectively; the double-layer reinforcement using 5-0 prolene suture line is represented by black; and the interrupted suture using 4-0 prolene suture line is represented by white.

Statistical analysis

SPSS 25.0 (SPSS, Inc., Chicago, IL, USA) and Python 3.10 were used for statistical analyses. Continuous variables were presented as mean ± standard deviation. Categorical variables are expressed as absolute numbers and proportions. Kaplan-Meier analysis was used to evaluate survival. Differences in categorical variables were analyzed using the χ² test. Differences in continuous variables were tested using the Student’s t-test or Mann-Whitney U-test. Multivariate analysis was performed using a binary logistic regression model to identify independent risk factors for in-hospital/30-day mortality. Statistical significance was established at values of P<0.05.

Results

Baseline characteristics and preoperative aortic dimensions

The preoperative demographic data are listed in Table 1. The average age of all patients was 51 [interquartile range (IQR), 44–57] years, and most of the patients were male individuals and those with hypertension. The RG included a higher proportion of patients with hypertension (88.1% vs. 59.1%) (P<0.001). Data including body mass index, diabetes history, smoking history, previous cardiogenic shock, and organ hypoperfusion were similar between the two groups (P>0.05). Significant differences were observed in preoperative aortic size between the two groups (P<0.05). The diameters of the ascending aorta, aortic sinus, and aortic annulus were significantly larger and the number of patients with moderate and the aforementioned aortic regurgitation was significantly higher in the BG than in the RG (P<0.05). In addition, patients in the BG had a lower preoperative creatinine level than that of patients in the RG (P=0.003). Furthermore, none of the patients in either group had Marfan syndrome or other connective tissue diseases.

Operative data

Table 2 details surgical procedures in both groups. No significant differences between the BG and RG were observed in terms of cardiopulmonary bypass (CPB) time, aortic cross-clamping time, or hypothermic circulatory arrest time (P>0.05). In addition, in the RG group, 3.9% of patients underwent valve repair (n=9), and 41% of patients underwent valve resuspension (n=93).

Postoperative data and complication

In the BG, 9 of the 215 patients received bioprosthetic valve composite grafts. A total of 48 patients in the two groups died during the perioperative period, and the in-hospital and 30-day mortality rates of patients in the RG and BG were 10.1% and 11.6%, respectively (P>0.05). No significant differences in prolonged ventilation ≥48 h, the need for tracheostomy, pneumonia, re-exploration for excessive bleeding, new-onset cerebrovascular accident, hemiplegia, paraplegia, new-onset renal failure, new-onset renal failure requiring continuous renal replacement therapy, sepsis, extracorporeal membrane oxygenation, and total length of hospital and intensive care unit stays were observed between the two groups (P>0.05) (Table 3).

Follow up

We evaluated the postoperative mortality and complications in 442 patients during hospitalization. The mean clinical follow-up duration for 394 patients who survived was 36.8±11.6 months (median, 33.4 months; IQR, 27.0–45.2 months), the follow-up rate was 100%. According to the results of the Kaplan-Meier analysis, the 5-year survival rate of the entire cohort was 86.8%, and the 5-year survival rates of the RG and BG were 88.1% and 85.9%, respectively (Figure 2) (P=0.65). During the follow-up period, only one patient in the BG underwent reoperation, involving Bentall and CABG surgery, at an interval of 3.6 years (P=0.431).

Figure 2 Long-term survival (Kaplan-Meier analysis) of patients with ATAAD after RG and BG. (A) Whole cohort; (B) separate subcohorts. BG, Bentall group; RG, repair group; ATAAD, acute type A aortic dissection.

Multivariate analysis

In the multivariate logistic regression analysis, preoperative creatinine level, preoperative cerebral malperfusion, and CPB time were identified as independent predictors of surgical mortality (P<0.05). The mortality rates were not significantly associated with the specific surgical methods employed for the aortic root and arch or whether CABG was performed (P>0.05) (Table 4).

Discussion

ATAAD is an immediately life-threatening disease associated with high mortality, and surgery is challenging. ATAAD often leads to aortic valve insufficiency and retrograde aortic root dissection, destroying the original physiological structure. Emergency surgery is the gold standard treatment for patients with ATAAD. Root surgery, such as Bentall’s procedure, has become the standard procedure and has improved the long-term prognosis of many patients, particularly those with Marfan syndrome or aortic root aneurysms. Considering that in most patients, the dissection does not involve the aortic annulus and aortic valve and often involves the non-coronary sinus rather than the left and right coronary sinus, the aortic root can be treated conservatively through new intimal reconstruction and aortic valve re-suspension, which may address the risks of aortic valve replacement-related complications including prosthetic valve endocarditis and lifelong anticoagulation. Many techniques have been developed for aortic valve preservation, such as aortic valvuloplasty and valve-sparing aortic root replacement, including remodeling (Yacoub surgery) and reimplantation (David surgery) (8,9). The long-term durability of this technology has been recognized; however, its complexity hinders its widespread promotion (10). Different repair techniques, such as the adventitial inversion technique (11), direct suture technique (12), patch neointima technique (13), and other methods, including sandwich technology, are the most widely used, and their effects have been recognized (14). This study used an improved sandwich technology that is simple and easy to implement.

In this study, the RG and BG’s in-hospital and 30-day mortality rates were relatively close at 10.1% and 11.6%, respectively. Brown et al. (4) reported 11.6% and 10.4% in-hospital mortality rates for root repair and replacement, respectively. Yang et al. (15) reported 30-day mortality rates of 6.2% and 8.2% in the two groups, and Xue et al. (16) reported 30-day mortality rates of 8.1% and 7.0%, respectively. In contrast, some studies suggested that root repair yields better outcomes than root replacement. For instance, Bojko et al. (3) reported that the hospital and 30-day mortality rates for root repair and replacement were 11.8% and 18.3%, respectively. Theoretically, aortic root replacement involves coronary artery separation and reimplantation, which may increase operative time and complexity. However, in this study, the CPB time and aortic occlusion time in the RG and BG were relatively similar, which may be attributed to the lack of proficiency of the surgical technicians. The reduction of the difficulty of the operation and the operation time through the application of new technology may be a gradual process. Other postoperative complications such as tracheotomy, secondary thoracotomy for hemostasis, neurological complications, and kidney injury were similar between the two groups, indicating that aortic root repair was safe and effective during the perioperative period.

In this study, the 5-year survival rates in the RG and BG were 88.1% and 85.9%, respectively. The mid-term survival rates were similar between the two groups, consistent with the findings of previous studies (3,16). Whether aortic root repair increases the risk of long-term reoperation has always been debated. The main reason for reoperation is to avoid aortic regurgitation caused by aortic sinus dilatation, dissection, or pseudoaneurysm (17,18). Another risk factor includes the use of gelatin-resorcinol-formaldehyde bioglue that may lead to aortic wall injury, as reported by Kirsch et al. and Izutani et al. (19,20). Additionally, Bojko et al. (3) reported that aortic sinus diameter of ≥45 mm and the presence of connective tissue disease are risk factors for proximal aortic reoperation. Castrovinci et al. (21) reported that root replacement reduces the need for proximal reoperation and should, therefore, be used in cases of intimal tears in the aortic root. Nishida et al. (22) reported that dissection involving two or more aortic sinuses is associated with late-stage aortic root repair requiring reoperation. In addition, we observed that performing conservative treatment is exceedingly challenging when the dissection severely damages the sinotubular junction. Because of the differences in indications and methods, reoperation rates in the middle and late stages of root repair differ among different centers. Rylski et al. (14) reported 10- and 15-year free proximal reoperation rates of 92%±2% and 89%±4%, respectively, using traditional sandwich techniques. Tang et al. (23) using the modified sandwich technique, reported that none of the patients required proximal aortic reintervention surgery in the past 5 years. Continuous improvements in root repair techniques may help reduce the rate of reoperations in the middle and late stages. Irimie et al. found that no patient had valve/root reintervention (>2+)-related insufficiency within an average follow-up of 70±50 months after aortic root repair (24). This study used a modified sandwich technique to insert a suitable Teflon felt after carefully removing the false thrombus lumen. Vascular grafts and autologous pericardium were placed on the inner and outer walls of the root to eliminate the false lumen and prevent long-term tearing. During the follow-up period, patients in the RG did not require proximal aorta reoperation and achieved excellent mid-term outcomes.

Limitations

This single-center retrospective observational study analyzed longitudinal data, different cerebral perfusion methods, improved sandwich techniques different from other centers, and the evolution of the surgeon’s surgical experience, may have affected the results. Secondly, the patient’s selective bias directly or indirectly affects the final result. For example, there were significant differences in ascending aortic diameter, aortic root and ring diameter, and the number of patients with preoperative moderate AI between the two groups due to different inclusion criteria. Patients who have undergone cardiac surgery also tend to undergo Bentall surgery; the perioperative risk of such patients is significantly higher. Finally, the sample size and follow-up time were limited, thereby restricting the universality of the results.

Conclusions

The choice of the aortic root surgery method had no effect on perioperative mortality. The mid-term survival rate of root repair surgery was similar to that of root replacement, with no proximal aortic reoperation performed during follow up. The application of improved sandwich technology at our center demonstrated safety and feasibility.

Acknowledgments

Funding: This research was funded by the National Natural Science Foundation of China (Nos. 82241204, 82270420 and 82070503), the Key R&D Program of Shaanxi Province (No. 2022ZDLSF02-01), and the Special Support Project for Basic Research of Shaanxi Province (No. 2023JC-XJ-11).

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-56/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-56/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-56/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-56/coif). W.D. reports that this study was supported by the National Natural Science Foundation of China (Nos. 82241204, 82270420 and 82070503), the Key R&D Program of Shaanxi Province (No. 2022ZDLSF02-01), and the Special Support Project for Basic Research of Shaanxi Province (No. 2023JC-XJ-11). The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This retrospective study was approved by The Ethics Committee of the First Affiliated Hospital of The Air Force Medical University (No. 20120216-4) and informed consent was taken from all the patients.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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