Midterm outcomes of concomitant ascending aorta replacement with rapid deployment aortic valve replacement

Introduction

Due to the progressive aging of the population and advances in medical technology, the number of patients with aortic valve disease is increasing, and the number of patients who benefit from aortic valve intervention, including transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (AVR), is also increasing (1,2). Among patients undergoing surgical AVR, the proportion receiving bioprosthetic AVR has gradually increased compared to those receiving mechanical AVR, has gradually increased, now reaching 60–90% (3,4). Among the bioprostheses for aortic valve substitutes, rapid-deployment (RD) valves have been recognized to have the advantages of significantly reducing procedural times, facilitating minimally invasive approaches, and improving hemodynamic profiles (5). The early and long-term results of RD valve surgery have been reported to be excellent (6,7).

A substantial portion of patients with aortic valve disease exhibit ascending aortic aneurysms, and the ascending aorta replacement is one of the most common concomitant procedures performed during AVR (8). Although several studies have shown that concomitant ascending aorta replacement during AVR is safe and has comparable outcomes to those of isolated AVR, there are still concerns about increased morbidities caused by concomitant aortic procedures.

In a previous study, our group demonstrated excellent midterm outcomes after AVR using the RD valve, particularly the Edwards Intuity (Edwards Lifesciences, Irvine, CA, USA) (9). However, it was unclear whether these excellent RD valve outcomes might also be valid in the subset of patients who require concomitant ascending aorta replacement for combined ascending aorta aneurysms.

The aim of this study was to evaluate the early and mid-term outcomes of patients who underwent AVR with rapid-deployment valve (RDAVR), and concomitant ascending aorta replacement compared to those who underwent isolated RDAVR. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1739/rc).

Methods

Study population

From June 2016 to June 2023, RDAVR using Edwards Intuity was performed on 344 patients at Seoul National University Hospital. Of the 344 patients, 26 had previous history of cardiac surgery, and 318 underwent primary AVR with an RD valve. After excluding the patients who underwent concomitant cardiac procedures, including mitral valve procedures (n=25), tricuspid valve procedures (n=5), coronary artery bypass grafting (n=18), arrhythmia surgery (n=11), and others (n=18), 130 patients who underwent RDAVR with concomitant ascending aorta replacement (Ao-AVR group) and 108 patients who underwent isolated RDAVR (Iso-AVR group) were ultimately enrolled (Figure 1). Because patients who needed concomitant root replacement for root aneurysm underwent Bentall/modified Bentall operation or valve-sparing root replacement during study period, there was no patient with aortic root aneurysm in the RDAVR cohort. Patients who received aortic valve repair were also excluded from this study. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study protocol was reviewed by the Institutional Review Board of Seoul National University Hospital and approved as a minimal risk retrospective study (approval No. H-2308-125-1459, date: 2023.01.09). The Institutional Review Board waived the requirement for individual informed consent as this study was a retrospective observational study.

Figure 1 Flow diagram of patient enrollment. CABG, coronary artery bypass grafting; RDAVR, aortic valve replacement with rapid-deployment valve.

Operative techniques and strategy

All operations were performed under standard median sternotomy with conventional cardiopulmonary bypass (CPB) and cardioplegia arrest. Body temperature was managed with mild hypothermia for isolated RDAVR or moderate hypothermia for concomitant ascending aorta replacement. The decision to replace the ascending aorta was decided based on not only the preoperative radiologic measurements but also the intraoperative findings and intraoperative measurements.

For cases of ascending aortic aneurysms, arterial cannulation was performed via the right axillary or innominate artery. Selective antegrade brain perfusion was performed by clamping the innominate artery for the distal anastomosis of the vascular graft to the most distal level of the ascending aorta. After the initiation of CPB, systemic cooling began, lowering the body temperature to the target of moderate hypothermia. Aortic cross-clamping (ACC) and aortic valve exploration are usually performed during systemic cooling. After reaching the target temperature, the innominate artery was clamped, and selective antegrade brain perfusion with or without left common carotid artery perfusion was initiated. The aneurysmal aorta was resected, and distal anastomosis of the vascular graft was performed at the most distal level of the ascending aorta, just proximal to the origin of the innominate artery. Subsequently, whole-body perfusion was restored by clamping off the innominate artery and clamping the vascular graft, and the RDAVR proceeded.

The surgical procedures of RDAVR have been described previously (10). After aortic valve excision and annular decalcification, the valve replica was simulated to the annulus. In cases where the replica did not entirely conform to the native annulus, especially in all cases of bicuspid valves, three guiding sutures and several additional sutures were placed at the surgeon’s discretion after careful inspection of the annular geometry, which were our modified techniques. After parachuting the valve into the annulus, the delivery system was temporarily removed to insert a 5-mm videoscope through the central hole of the valve holder for internal inspection. The valve position at the left ventricular outflow tract, spatial relationship with the anterior leaflet of the mitral valve, and any loosening or displacement of the guiding sutures were carefully examined. The delivery system was reassembled for balloon expansion at 4.5 or 5.0 atm for 10 seconds. The videoscope was reinserted to confirm adequate subannular expansion, correct prosthesis position, and any related abnormalities. After confirmation, the guiding sutures were tied, and proximal anastomosis of the ascending aorta graft was completed (Figure 2).

Figure 2 Operative procedures of RDAVR with concomitant ascending aorta replacement. (A) Innominate artery cannulation was performed using 8 mm vascular graft in the sternotomy field (white asterisk). (B) After the aortic cross-clamp was established, aortic valve exploration was performed during further systemic cooling to reach the target temperature for circulatory arrest with selective unilateral antegrade cerebral perfusion. Valve exploration revealed a type 0 bicuspid valve with calcification. (C) Leaflets were excised, and the annulus was trimmed. (D) When the patient reached the target temperature, the innominate artery was clamped, and selective antegrade brain perfusion with left common carotid artery perfusion was performed. Vascular clamps were placed at the proximal innominate artery and left common carotid artery (white arrow heads). The aneurysmal ascending aorta was then resected. (E) Distal anastomosis of the vascular graft for ascending aorta replacement was performed. After completion of distal anastomosis, the vascular clamps were removed, the ascending aorta graft was clamped, whole-body perfusion was resumed, and systemic rewarming was initiated. (F) RDAVR was performed using 3 guiding sutures with additional sutures to achieve complete annular fitting. (G) The valve was successfully deployed to the annulus of a type 0 bicuspid valve, and the guiding sutures were tied. (H) Proximal anastomosis of the ascending aorta graft was performed, and the aortic cross-clamp was released. RDAVR, aortic valve replacement with rapid-deployment valve.

Evaluation of early outcomes

Operative mortality was defined as any death within 30 days after surgery or during the same hospital admission. Continuous electrocardiography monitoring was applied to all patients until discharge, and the detection of any short runs of atrial fibrillation was regarded as the occurrence of postoperative atrial fibrillation. Low cardiac output was defined as a cardiac index <2.0 L/min/m² or a systolic arterial pressure <90 mmHg requiring inotropic support (dopamine or dobutamine) >5 mg/kg/min or mechanical circulatory support (e.g., intra-aortic balloon pump). Acute kidney injury was defined as a twofold increase in the serum creatinine level from the preoperative value, a decrease in the glomerular filtration rate of 50%, a urine output <0.5 mL/kg/h for 12 hours or the need for renal replacement therapy regardless of the serum creatinine level. Respiratory complications included prolonged ventilation over 48 hours postoperatively, pneumonia, or the need for tracheostomy.

Evaluation of midterm outcomes

After discharge, all patients underwent regular postoperative follow-ups through the outpatient clinic at 3- or 4-month intervals and were interviewed by telephone for confirmation of their condition if the last clinic visit had not been conducted as scheduled. For the patients who were lost to follow-up, survival or mortality was confirmed via the use of the National Health Insurance Database. The clinical follow-up ended on July 31, 2023. The follow-up data were completed for 92.0% (219/238), and the remaining 19 patients were confirmed to be alive based on the National Health Insurance Database. The median follow-up duration was 31.2 months [interquartile range (IQR), 14.0, 55.1].

Cardiac death was defined as all deaths resulting from cardiac causes, including valve-related deaths, sudden unexplained deaths, and deaths from nonvalve-related cardiac causes (e.g., heart failure, myocardial infarction, or documented arrhythmias). Aortic valve-related events (AVREs) were defined as valve-related mortality, structural valve deterioration, nonstructural dysfunction, valve thrombosis, embolism, bleeding events, operated valve endocarditis, operated valve reoperation, or permanent pacemaker insertion (11).

To stress the validity of index surgical indication, the diameters of aortic root were evaluated by preoperative, early postoperative, and follow-up echocardiograms in all study patients. The changes in the diameters of aortic root were analyzed, and subgroup analysis was performed particularly in the patients with bicuspid aortopathy.

Statistical analysis

Statistical analysis was performed using IBM SPSS statistics software version 27.0 (IBM Inc., Armonk, NY, USA) and SAS software, version 9.4 (SAS Institute, Cary, NC, USA). Continuous variables are presented as the mean ± standard deviation for normally distributed data or the median with IQR for data that were not normally distributed, whereas categorical variables are presented as the number and percentage of the subjects. Comparisons of baseline patient characteristics, operative data, and early clinical outcomes between the groups were performed using the chi-square test or Fisher’s exact test for categorical variables, and Student’s t-test or the Mann-Whitney test for continuous variables, as appropriate. Overall survival was estimated using the Kaplan-Meier method, and comparisons between the two groups were performed using the Cox proportional hazards model. The cumulative incidences of cardiac death and AVREs were evaluated using the Fine-Gray subdistribution hazard model, considering noncardiac death and all-cause death as competing risk, respectively. To identify the risk factors for all-cause mortality, univariate and multivariate analyses were performed using the Cox proportional hazards model. In the multivariate analysis, variables with a P value <0.1 in the univariate analysis were included in a stepwise selection with a threshold P value <0.05. The changes in the diameters of aortic root were analyzed with repeated measures analysis of variance. All tests were two-tailed, and a P value <0.05 was considered indicating statistical significance.

Results

Preoperative characteristics

The mean age was younger in the Ao-AVR group than in the Iso-AVR group (67.8±9.0 vs. 70.8±9.7 years, P=0.01). The Ao-AVR group had fewer preoperative risk factors, including diabetes mellitus (16.2% vs. 29.6%, P=0.01), chronic kidney disease (9.2% vs. 26.9%, P<0.001), and coronary artery disease (7.7% vs. 21.3%, P=0.002), than did the Iso-AVR group. However, the EuroSCORE II was higher in the Ao-AVR group than in the Iso-AVR group (2.95±3.41 vs. 1.87±1.34, P=0.001). Bicuspid aortic valvulopathy was the main etiology in the Ao-AVR group (71.5%), whereas degenerative calcific valvulopathy was the main etiology in the Iso-AVR group (55.6%). The diameter of the ascending aorta measured via preoperative computed tomography was 45.7±5.9 and 37.5±3.6 mm (P<0.001) in the Ao-AVR group and Iso-AVR group, respectively. Emergency operation was required 1 patient from each group due to very severe aortic stenosis with decompensating congestive heart failure (Table 1).

Operative data

In the Ao-AVR group, arterial cannulation was performed at the innominate artery (76.9%) or axillary artery (11.5%), whereas it was mostly placed at the ascending aorta (66.7%) in the Iso-AVR group. The Ao-AVR group required 21 minutes of longer CPB (162 vs. 141 minutes, P<0.001) and 28 minutes of longer ACC (116 vs. 88 minutes, P<0.001) than did the Iso-AVR group. The median selective antegrade brain perfusion time was 12 minutes (IQR 9, 16) in the Ao-AVR group. The most common valve sizes implanted were 23 mm (30.8%), 21 mm (28.5%) and 25 mm (19.2%) in the Ao-AVR group, 21 mm (37.0%), 23 mm (26.9%) and 19 mm (18.5%) in the Iso-AVR group (Table 2).

Early outcomes

The operative mortality rate was 0.0% (0 out of 130) in the Ao-AVR group and 2.8% (3 out of 108) in the Iso-AVR group (P=0.09). Postoperative atrial fibrillation occurred more frequently in the Ao-AVR group than in the Iso-AVR group (46.9% vs. 34.3%, P=0.048). Other postoperative complications, including acute kidney injury, respiratory complications, low cardiac output, bleeding reoperation, permanent pacemaker implantation, stroke, and mediastinitis, were not significantly different between the groups (Table 3).

Midterm outcomes

Midterm overall survival was higher in the Ao-AVR group (P=0.002), with 100.0% vs. 94.4% at 1 year, 98.9% vs. 92.0% at 3 years, and 98.9% vs. 76.6% at 5 years in the Ao-AVR vs. Iso-AVR groups, respectively. The cumulative incidence of cardiac death was not significantly different between the groups (P=0.09), with 0.0% vs. 3.7% at 1 year, 1.1% vs. 3.7% at 3 years, and 1.1% vs. 6.6% at 5 years in the Ao-AVR vs. Iso-AVR groups, respectively. There were also no significant differences in the cumulative incidence of AVREs between the groups (P=0.65): 8.8% vs. 8.4% at 1 year, 11.3% vs. 13.3% at 3 years, and 13.7% vs. 20.1% at 5 years in the Ao-AVR vs. Iso-AVR groups, respectively (Figure 3).

Figure 3 The comparative midterm outcomes between the concomitant ascending aorta replacement during Ao-AVR group and the Iso-AVR group. (A) Overall survival. (B) the cumulative incidence of cardiac death, and (C) the cumulative incidence of aortic valve-related events in the study population. Ao-AVR, concomitant ascending aorta replacement during aortic valve replacement with rapid-deployment valve; AVRE, aortic valve-related event; Iso-AVR, isolated aortic valve replacement with rapid-deployment valve.

Multivariate analysis revealed that the risk factors associated with midterm all-cause mortality were chronic obstructive pulmonary disease [P=0.03, hazard ratio (HR) =3.98, 95% confidence interval (CI): 1.13–14.03] and emergency operation (P<0.001, HR =94.77, 95% CI: 8.20–1,094.8). Concomitant ascending aorta replacement during RDAVR was not a factor increasing the risk of midterm all-cause mortality (Table 4).

The changes in the diameters of aortic root demonstrated no significant difference during follow-up in both groups, and they also demonstrated no significant difference in the subgroup patients with bicuspid aortic valves (BAVs) (Tables S1,S2).

Discussion

The present study demonstrated 3 main findings. First, the patients who underwent concomitant ascending aorta replacement during RDAVR in this study population were younger, less morbid, and more likely to have bicuspid valvulopathy than were those who underwent isolated RDAVR. Second, the operative mortality of RDAVR with concomitant ascending aorta replacement was 0.0%, and the early clinical outcomes were comparable to those of isolated RDAVR, except for the occurrence of postoperative atrial fibrillation. Third, multivariate analysis demonstrated that concomitant ascending aorta replacement was not a factor increasing the risk of midterm all-cause mortality.

The BAV is the most common congenital cardiac abnormality affecting approximately 1–2% of the population (12). In particular, BAV is recognized as underlying almost 50% of isolated severe aortic stenosis cases requiring surgery (13). Although aortic stenosis and regurgitation are the most common complications of BAV, dilatation of any segments of the proximal aorta from the aortic root to the aortic arch, called bicuspid aortopathy, is also present in approximately 50% of affected patients (12). Significant aortic dilation greater than 45 mm developed during 25 years of follow-up even in 25% of the patients who had no baseline aneurysm at the first diagnosis of BAV (14). In addition, BAV patients were likely to be younger and had fewer comorbidities than patients with tricuspid aortic valve (TAV), as was the case in our study (15,16).

In patients requiring concomitant ascending aorta replacement during AVR, the additional procedure inevitably introduces extra risk. Prolonged CPB and ACC time associated with aortic surgery might result in poorer early and late outcomes than isolated AVR. The use of hypothermic circulatory arrest for hemiarch or total arch replacement adds additional complexity and morbidity to the operation. Therefore, the indications for concomitant intervention on the thoracic aorta at the time of AVR are still controversial (17,18).

According to the guidelines, concomitant repair of the ascending aorta is recommended when the aortic diameter is ≥45 mm in patients undergoing cardiac surgery regardless of aortic valve type (19-21). However, there are controversies about the replacement of moderately dilated, so-called ‘borderline’, ascending aorta with an aortic diameter <45 mm. A recent real-world study showed that more than one-third of patients with BAVs undergo ascending aorta intervention with aortic diameters <45 mm (22).

In BAVs, progressive ascending aortic dilatation is known to be attributed to hemodynamic and genetic factors (12). Although the hemodynamic factor, which is the abnormal shear stress leading to the formation of aneurysms, disappears after AVR, the genetic factor persists, potentially leading to further dilation due to medial degeneration, which is characterized by vascular smooth muscle cell apoptosis, reduced collagen content, and elastic fiber fragmentation (23). A previous study showed a higher risk of late ascending aorta aneurysm or dissection in patients with BAV and insisted on performing prophylactic replacement even in a seemingly normal and mildly enlarged ascending aorta (24). Several studies demonstrated that the rate of late adverse aortic events was significantly higher in the BAV group than in the TAV group, particularly in the isolated aortic regurgitation subgroup (25,26).

In contrast, it has also been suggested that the incidence of aortic events after isolated AVR in BAV is very low and similar to that in TAV (15,16,25,26). Although the natural expansion rate of the ascending aorta is reportedly 0.2–1.9 mm per year in a BAV, the postoperative expansion rate is much lower (12,23,27). Another study even suggested not replacing the proximal aorta of 40–45 mm in diameter during AVR in BAV patients (28).

In our study, the operative mortality of RDAVR with concomitant ascending aorta replacement was 0.0%. We think these excellent outcomes are attributed to both the relatively young age of the concomitant ascending aorta replacement population and the minimal procedural risk posed by the additional procedure of ascending aorta replacement. Also, concomitant replacement of the ascending aorta demonstrated comparable early and midterm clinical outcomes to those of isolated AVR. These findings are consistent with previous studies that compared isolated AVR versus AVR with ascending aorta replacement and showed no differences in perioperative mortality between the groups (29,30). To treat ascending aorta aneurysms, wrapping or reduction aortoplasty, instead of replacement, has been suggested as an alternative option. However, the long-term durability of these approaches is questionable. A significantly higher percentage of patients who underwent wrapping had proximal arch redilatation than did patients who underwent replacement (31). In patients undergoing reduction aortoplasty, the thickness and quality of the dilated native aorta are suboptimal because a thinner wall is associated with greater wall stress and is prone to redilatation according to the Laplace law (32). Thus, the replacement of a borderline ascending aorta, which imposes little additional risk to the isolated RDAVR, would be the most durable and safest treatment option in patients receiving RDAVR with a dilated ascending aorta because it eliminates the risk of aortic dissection and redilatation.

In this study population, axillary or innominate artery cannulation was preferred to the classical proximal aortic arch cannulation. It is true that classical proximal aortic arch cannulation would allow a safe and appropriate site for ACC in some cases. In other cases, however, severe atherosclerosis or calcification in ascending aorta could interfere safe placement of ACC and could increase the chances of postoperative embolic stroke. Also, pathologic native distal ascending aorta still remains after ascending aorta replacement if the procedure is performed while the ACC is placed in the distal ascending aorta. For these reasons, axillary or innominate artery cannulation with brief total circulatory arrest and selective antegrade cerebral perfusion was the preferred strategy in these series. Although the anastomosis of the graft to the distal ascending aorta took around 10 minutes, moderate hypothermia, rather than mild hypothermia, was used to reduce the chance of cerebral and visceral complications. We believe that this strategy reduces the chances of embolic stroke caused by atheroma or calcification in ascending aorta, and also enables extensive replacement of the whole ascending aorta from sinotubular junction to distal ascending aorta just below the origin of the innominate artery.

The procedural times in our study were relatively long compared with those in other studies regarding RDAVR. It might be related to our RD valve implantation technique: the use of a 5-mm videoscope for direct visual inspection of valve positioning to the annulus and left ventricular outflow tract and the additional anchoring sutures to achieve ‘complete annulus fitting’. Although this technique may increase the procedural times, it helped to reduce the occurrence of complete atrioventricular block after RDAVR to 1.4% (9).

Limitations

Several limitations should be noted. First, this was a retrospective, single-center study with a small sample size and a relatively short follow-up period. Second, the baseline characteristics, including age and comorbidities, differed significantly between the two groups in this study. Although multivariable analysis was performed to adjust for these differences, substantial caution is needed in the interpretation of the results. Despite inherent biases and challenges in the analysis, we aimed to demonstrate the excellent outcomes of patients who underwent concomitant ascending aorta replacement with RDAVR, focusing on its safety and efficacy, by comparing their outcomes to those of patients who underwent isolated RDAVR. Further prospective, multi-institutional research is needed to overcome these limitations. Third, conventional Sievers classification (33) was used in the classification of bicuspid valves, since some of the patients were operated before the recent consensus (34) was published.

Conclusions

In conclusion, concomitant ascending aorta replacement during RDAVR demonstrated excellent early and midterm outcomes, and those outcomes were comparable to the outcomes of isolated RDAVR.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1739/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1739/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1739/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1739/coif). K.H.K. is an official proctor for Edwards Lifesciences. 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 and its subsequent amendments. The study protocol was reviewed by the Institutional Review Board of Seoul National University Hospital and approved as a minimal risk retrospective study (approval No. H-2308-125-1459, date: 2023.01.09). The Institutional Review Board waived the requirement for individual informed consent as this study was a retrospective observational study.

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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