Renal artery involvement as a predictor of severe malperfusion in acute type A aortic dissection: a retrospective cohort study

Introduction

Acute type A aortic dissection (ATAAD) is a complex and potentially catastrophic condition characterized by an intimal tear that can propagate distally along the aorta, frequently involving its major branch vessels and leading to end-organ ischemia or malperfusion syndrome (1). Malperfusion syndrome, resulting from critical end-organ ischemia, is the predominant driver of adverse outcomes in ATAAD, with a direct correlation between the number of affected organ systems and mortality (2,3). However, a simple and reliable clinical or radiographic indicator to comprehensively assess the severity and extent of the disease at presentation remains an unmet clinical need.

The development of image-based aortic markers holds promise for identifying high-risk features in ATAAD and can provide crucial information to guide clinical decision-making and optimize treatment strategies for these patients (4). The renal artery, located distal to the primary aortic branches, has received relatively little attention in the context of ATAAD. We hypothesized that renal artery involvement (RAI) in ATAAD reflects a more extensive and severe dissection, thereby correlating with a greater burden of branch vessel compromise and a higher incidence of clinically significant malperfusion. The primary objective of this study was therefore to determine whether the presence of RAI on preoperative imaging can serve as a reliable indicator of the overall extent and severity of aortic branch compromise and the risk of perioperative end-organ malperfusion in patients undergoing surgery for ATAAD. Unlike existing risk stratification tools, such as the Penn classification, which rely on clinical signs of end-organ dysfunction or on composite calculations, RAI is a purely anatomical, binary marker that can be instantly assessed on admission computed tomography angiography (CTA). The incremental value of RAI lies in its ability to identify a high‑risk subset of patients who have subclinical yet anatomically extensive branch vessel compromise, thereby enabling proactive surveillance and surgical planning well before irreversible malperfusion occurs. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0770/rc).

Methods

Patient population

This project is a retrospective cohort study conducted at Fuwai Hospital, which initially identified 510 consecutive patients who underwent open surgical repair for ATAAD at our institution between January 2020 and June 2022. Patients were excluded if they met any of the following criteria: (I) renal atrophy or agenesis; (II) severe renal artery stenosis; (III) chronic kidney disease requiring ongoing dialysis or medical therapy. Consequently, 39 patients were excluded based on these criteria, including two with left renal atrophy, one with right renal agenesis, and two with severe bilateral renal artery stenosis. The RAI was defined on preoperative CTA as the dissection membrane extending to the ostium of the renal artery, with the renal artery originating from the false lumen or being supplied by both true and false lumens. After applying the exclusion criteria, the final study population comprised 471 patients. Based on the CTA definition above, these patients were stratified into two groups: the RAI group (n=289) and the non-RAI group (n=182). The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of Fuwai Hospital (No. 2021− 1490, approved on Dec 6th, 2021). Informed consent was waived because of the retrospective nature.

Definition of adverse outcomes and study endpoints

To ensure data integrity and accuracy, all preoperative CTA images and corresponding clinical reports were independently reviewed by two experienced cardiologists. In cases of diagnostic disagreement, a third-party adjudication was performed by a senior radiologist. Clinical and follow-up data were double-entered into a dedicated database from outpatient records to minimize missing information and ensure data accuracy. Aortic branch involvement was defined according to criteria established in the previous literature (1). Malperfusion was defined as clinical and/or radiographic evidence of end-organ ischemia resulting from compromised blood flow due to dissection involvement of the corresponding aortic branch. The primary objective of this study was to assess RAI as an anatomical marker of overall branch vessel compromise burden, rather than to elucidate the specific pathophysiology of renal malperfusion. Therefore, we did not routinely differentiate dynamic from static renal malperfusion based on CTA. The RAI was defined on preoperative CTA as the extension of the dissection membrane to the ostium of the renal artery, with the renal artery arising from the false lumen or receiving blood supply from both the true and false lumens. Serious adverse events (SAEs) were defined as a composite endpoint comprising any of the following in-hospital postoperative complications: operative mortality, permanent stroke, or postoperative cardiac failure requiring extracorporeal membrane oxygenation or intra-aortic balloon pump support. Operative mortality was defined as death occurring during the index hospitalization or within 30 days after surgery, whichever was longer. Mid-term mortality was defined as all-cause mortality occurring after hospital discharge among patients who survived to discharge.

Postoperative serum creatinine (SCr) and blood urea nitrogen (BUN) levels were prospectively recorded at serial time points. Data were captured at three distinct time points: immediately postoperatively, the peak value within the first 48 hours after surgery, and the peak value during the entire hospitalization period.

Surgical technique

All patients underwent surgery via a median sternotomy. Cardiopulmonary bypass (CPB) was established with arterial cannulation via the right axillary artery, with or without additional femoral arterial cannulation. The surgical strategy for ATAAD primarily varied in the extent of aortic arch reconstruction, which was classified as either total arch replacement (TAR) or hemi-arch replacement. The choice between TAR with frozen elephant trunk (FET) implantation and hemi-arch replacement was individualized based on patient characteristics and anatomical findings. Our institutional preference favored TAR with FET implantation to promote true lumen expansion and facilitate favorable remodeling of the proximal descending aorta, particularly in younger patients or those with extensive distal aortic dissection. FET was systematically preferred when the primary intimal tear was located in the aortic arch or when preoperative visceral malperfusion was present. Conversely, a more limited hemi-arch replacement was considered for elderly patients, those without an entry tear in the aortic arch, or those presenting with profound hemodynamic instability or severe preoperative neurological deficits, situations in which minimizing circulatory arrest time was paramount.

For patients undergoing TAR with FET implantation, the procedure was performed either as conventional TAR combined with FET implantation or as a type II hybrid total arch repair, as previously described (5-8). Selective antegrade cerebral perfusion (SACP) was instituted during periods of circulatory arrest for cerebral protection, with a perfusion flow rate of 6–10 mL/kg/min. Regional cerebral oxygen saturation was routinely monitored, and nasopharyngeal temperature was maintained at 20–28 ℃ during circulatory arrest. Lower body circulatory arrest with exclusive SACP was maintained during the implantation of the FET and during the anastomosis of the proximal end of the FET to the distal end of the four-branch graft. The type II hybrid arch repair was performed according to previously described protocols, with nasopharyngeal temperature maintained at approximately 25–28 ℃ (6,7). This technique involved the deployment of a commercially available thoracic aortic stent-graft, followed by reconstruction of the supra-aortic branches. For patients undergoing hemi-arch replacement, deep hypothermic circulatory arrest and selective cerebral perfusion were not routinely required. Thus, the fundamental distinction between these surgical strategies lay in the requirement for hypothermic circulatory arrest and selective cerebral perfusion.

Follow-up

Among hospital survivors, information about the health status of patients after discharge was obtained through annual outpatient revisit records or through telephone interviews to inquire about their postoperative recovery. Follow-up ended in July 2024.

Statistical analysis

All statistical analyses were conducted using R statistical software (version 4.3.1). A two-tailed P value <0.05 was considered statistically significant. Continuous variables were presented as mean ± standard deviation if normally distributed, and as median with interquartile range (IQR) if not. Categorical variables were presented as frequency and percentage.

To minimize baseline differences, propensity score matching (PSM) was performed using the following covariates: age, gender, body mass index, hypertension, diabetes, coronary artery disease, anticoagulant use, bicuspid aortic valve, preoperative left ventricular ejection fraction, and total bilirubin. Nearest-neighbor 1:1 matching without replacement, with a calliper width of 0.1, resulted in 150 matched pairs (300 patients).

Continuous variables were compared using the independent t-test or Mann-Whitney U test, and categorical variables using the chi-squared (χ²) or Fisher’s exact test. Ordinal variables were analyzed with rank sum tests. After PSM, paired t-tests, Wilcoxon signed-rank tests, and McNemar tests were used. Multivariable ordered logistic regression was used to report proportional odds ratios (ORs) and the probabilities of malperfusion (including cerebral, coronary, and visceral malperfusion). Multivariable Cox proportional hazards models were employed to identify risk factors for overall survival and mid-term mortality, as well as lifelong dialysis.

Results

Baseline demographic and clinical characteristics of the study population are summarized in Table 1. Before PSM, the RAI and non-RAI groups differed significantly in several baseline characteristics, including age, sex, body mass index, coronary artery disease, pericardial tamponade, and aortic valve regurgitation (P<0.05). After PSM, these differences were effectively balanced, with all covariates demonstrating a standardized mean difference of less than 10%, indicating successful matching (Figure 1).

Figure 1 All variables have an SMD <0.1, indicating well baseline matching. LVEF, left ventricular ejection fraction; PSM, propensity score matching; SMD, standardized mean difference.

The characteristics of renal and other aortic branch vessel involvement are detailed in Table 2. Among the entire cohort, left RAI was observed in 225 patients, and right RAI in 104 patients. The RAI group exhibited a significantly higher prevalence of branch vessel involvement, affecting the right coronary artery, supra-aortic branches, celiac artery, mesenteric artery, and lower extremity arteries (P<0.05). Involvement of the left coronary artery was similar between groups. Furthermore, the burden of malperfusion, quantified as the number of affected end-organs, was significantly higher in the RAI group (P=0.006). Preoperative renal function was also worse in the RAI group, as reflected by significantly higher SCr levels (90.65 vs. 83.98 µmol/L, P=0.004). These differences in branch vessel involvement, malperfusion burden, and preoperative renal function remained statistically significant after PSM.

Intraoperative data and surgical details are summarized in Table 3. The distribution of surgical strategies employed for the aortic root and aortic arch was similar between the two groups. However, patients in the RAI group more frequently required concomitant aortic branch procedures (21.11% vs. 8.79%, P<0.001). Consequently, before PSM, patients in the RAI group had longer total operative times, CPB times, aortic cross-clamp times, and lower body circulatory arrest times. After PSM, these differences remained statistically significant for total operative time, CPB time, and circulatory arrest time.

Early outcomes

Early postoperative outcomes are summarized in Table 4. Overall, in-hospital mortality was low, with ten deaths (2.1%) occurring during hospitalization. However, the incidence of SAEs was significantly higher in the RAI group (23 patients, 7.96%) compared to the non-RAI group (4 patients, 2.20%; P=0.009). This difference in SAE incidence persisted after PSM, remaining significantly higher in the RAI group (10.00% vs. 2.00%, P=0.004). Furthermore, the need for postoperative dialysis was significantly higher in the RAI group (11.07% vs. 3.30%, P=0.003). Patients in the RAI group also had significantly elevated serum SCr levels at all three measured postoperative time points, as well as higher immediate postoperative BUN levels, and experienced prolonged intensive care unit (ICU) stays (P<0.05). These differences in postoperative renal function parameters and ICU stay remained statistically significant after PSM.

In a multivariable ordered logistic regression analysis adjusted for age and sex, renal involvement remained independently associated with a greater number of malperfused organ systems [OR =2.00; 95% confidence interval (CI): 1.25–3.27; P=0.005] (Table S1). The multivariable ordered logistic regression model demonstrated satisfactory discriminative ability, with an area under the curve of 0.741, reflecting good discriminatory power. Additionally, the Hosmer-Lemeshow goodness-of-fit test (P=0.51) indicated that the model adequately fitted the data.

Follow-up

Follow-up was complete for 95.33% of the cohort; 22 patients (and their families) were lost to follow-up despite multiple attempts to contact them. The median follow-up duration for hospital survivors was 156 weeks (IQR, 124–184 weeks). During this period, 11 deaths were recorded among these patients. In the multivariable Cox proportional hazards analysis, preoperative RAI emerged as an independent risk factor for overall mortality [hazard ratio (HR) =3.48; 95% CI: 1.15–10.47; P=0.03], as illustrated in Figure 2. The RAI was also an independent risk factor for mid-term mortality among hospital survivors (HR =3.42; 95% CI: 1.14–10.31; P=0.03). Kaplan-Meier analysis did not detect a statistically significant association between RAI and the cumulative incidence of postoperative dialysis dependence, both when considering all surgical patients (log-rank P=0.18) and when restricted to hospital survivors (log-rank P=0.16) (Figure S1A,S1B).

Figure 2 Forest plot showing independent risk factors for all-cause mortality identified by multivariable Cox proportional hazards analysis. CI, confidence interval; HR, hazard ratio; LVEF, left ventricular ejection fraction.

Discussion

The principal finding of this study is that RAI on preoperative CTA represents a reliable marker of greater extent and severity of aortic branch compromise and that it is independently associated with a higher malperfusion burden. Furthermore, the RAI was associated with poorer short-term postoperative outcomes and independently predicted mid-term mortality, yet it did not confer an increased risk of long-term dialysis dependence.

The aortic dissection frequently involves the major aortic branch vessels. Previous studies have established that branch vessel involvement is a serious and common complication, with the potential to cause lethal end-organ malperfusion and significantly worsen clinical outcomes (1,9). Moreover, a direct correlation has been demonstrated between the extent of branch-vessel compromise and clinical prognosis. Consequently, identifying a simple and reliable indicator to evaluate the overall severity and extent of ATAAD is of critical clinical importance. The findings of the present study suggest that RAI may serve as precisely such an indicator. Different from the Penn classification, RAI provides a simple, objective, and reproducible anatomical anchor. The advantages of RAI are threefold. It can be assessed on standard admission CTA without additional software or measurement. Moreover, it identifies patients with a higher burden of multivessel compromise even when clinical malperfusion is not yet manifest. Furthermore, it predicts worse perioperative outcomes and mid-term survival independently of conventional malperfusion definitions. By incorporating RAI into routine CTA reporting, clinicians can promptly identify a high‑risk cohort that warrants closer malperfusion monitoring, earlier consideration of total arch repair with the FET technique, and more aggressive postoperative renal protection strategies.

Accurately assessing the severity and extent of ATAAD remains challenging, largely due to the complex and variable morphology of the dissected aorta, and existing radiographic indicators are often inadequate. Currently available classification systems are often complex, difficult to apply in routine clinical practice, and have undergone limited external validation (10,11). In line with our hypothesis, we observed that patients in the RAI group exhibited significantly more severe branch vessel compromise and a higher incidence of end-organ malperfusion. The underlying hemodynamic mechanisms of ATAAD propagation can explain this association. The initial intimal tear allows high-pressure, pulsatile blood to enter and pressurize the false lumen, driving its distal extension under the influence of antegrade flow. Branch vessels along the aortic course may serve to dissipate some of this hemodynamic energy. Therefore, when the false lumen extends to the level of the renal arteries, this anatomical finding signifies that the initial tear was subjected to a sufficiently powerful hemodynamic force to propagate the dissection to the distal aorta. In our cohort, this finding was strongly associated with a greater likelihood of branch vessel compromise along its entire course, a finding consistent with our CTA observations (12). This anatomical severity was further reflected in the operative outcomes, as patients in the RAI group more frequently required concomitant branch vessel procedures, a direct consequence of more severe compromise in the corresponding arteries. Consequently, the significantly longer operative, CPB, and circulatory arrest times observed in the RAI group are a testament to the increased technical demands and complexity of treating these patients. In summary, RAI emerges as a straightforward, objective, and effective radiographic indicator for assessing the overall severity and extent of aortic branch compromise in ATAAD.

Our study also demonstrates that patients with RAI experience significantly worse short-term surgical outcomes. This is likely attributable to the broader branch vessel compromise and higher burden of malperfusion associated with RAI, which collectively increase the risk of postoperative complications and necessitate more complex surgical interventions, ultimately impacting early prognosis (13,14). Importantly, however, RAI does not equate to irreversible long-term renal injury. Despite higher rates of acute postoperative renal dysfunction, the incidence of permanent dialysis dependence was not significantly different between the two groups. First, bilateral RAI was infrequent in our cohort, and the robust compensatory capacity of the contralateral kidney likely mitigated the need for long-term renal replacement therapy in most cases. Second, acute kidney injury in the postoperative setting is often multifactorial and reversible. The need for dialysis in the acute phase is frequently driven by systemic factors—such as pre-renal hypoperfusion, hypothermia, nephrotoxic agents, or visceral ischemia—rather than irreversible ischemic damage from the dissection itself. Consequently, the requirement for dialysis typically diminishes over time, facilitated by early detection of renal injury and timely intervention. In summary, while RAI is a marker of acute disease severity and postoperative renal dysfunction, it does not significantly increase the likelihood of permanent dialysis dependence.

We deliberately chose anatomical RAI over functional parameters like SCr or clinical renal malperfusion as our primary indicator. The SCr is a nonspecific marker in the acute setting, influenced by numerous perioperative factors (e.g., metabolic acidosis, effects of hypothermic circulatory arrest, cardiac tamponade-related hypotension) and therefore does not accurately reflect the anatomical extent of branch vessel compromise. Furthermore, while imaging features like differential renal enhancement may be suggestive, they are not prescriptive for a diagnosis of irreversible renal malperfusion, further limiting their value as a proxy for the overall extent of ATAAD compromise (15).

This study has several limitations. First, despite the use of PSM to minimize selection bias, residual confounding may persist due to its retrospective, observational design. Second, patients with the most severe and extensive ATAAD may have succumbed to their condition before surgical intervention could be undertaken, potentially introducing a survivorship bias (akin to Berkson’s bias) into our cohort of surgically treated patients. Nonetheless, this study provides significant clinical value by identifying a simple, objective, and readily available radiographic indicator—RAI—that reliably reflects the overall extent and severity of ATAAD and its associated risk of malperfusion. Future large-scale, prospective studies are warranted to further delineate the independent prognostic impact of RAI, separate from the influence of pre-existing or hyperacute renal dysfunction.

Conclusions

The RAI of ATAAD on preoperative CTA is a simple and reliable indicator of more extensive aortic branch compromise and a higher burden of malperfusion in patients with ATAAD. Its presence identifies a high-risk cohort with worse perioperative outcomes and reduced mid-term survival, yet it does not predict long-term dialysis dependence. Incorporating RAI into routine preoperative risk stratification may facilitate the timely identification of high-risk patients and guide more aggressive surveillance for malperfusion. Future prospective studies are warranted to validate these findings and to explore whether RAI can inform individualized surgical strategies to further improve outcomes.

Acknowledgments

The authors thank Long Deng, Dong Zhao, and other surgeons for serving as the excellent consultants for this article. The authors also extend their sincere gratitude and best wishes to all colleagues.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0770/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0770/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0770/prf

Funding: This work was supported by Chinese Academy of Medical Sciences Innovation Fund for Medical Science (No. 2020-I2M-C&T56 B-059) and Key Project of the National Center for Cardiovascular Diseases, Fuwai Hospital (Project No. 2018F-F02).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0770/coif). The 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 was approved by the Ethics Committee of Fuwai Hospital (No. 2021− 1490, approved on Dec 6th, 2021). Informed consent was waived because of the retrospective nature.

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/.

References

1. Authors/Task Force Members. EACTS/STS Guidelines for Diagnosing and Treating Acute and Chronic Syndromes of the Aortic Organ. Ann Thorac Surg 2024;118:5-115. [Crossref] [PubMed]
2. Norton EL, Khaja MS, Williams DM, et al. Type A aortic dissection complicated by malperfusion syndrome. Curr Opin Cardiol 2019;34:610-5. [Crossref] [PubMed]
3. Berretta P, Trimarchi S, Patel HJ, et al. Malperfusion syndromes in type A aortic dissection: what we have learned from IRAD. J Vis Surg 2018;4:65. [Crossref] [PubMed]
4. Isselbacher EM, Preventza O, Hamilton Black J 3rd, et al. 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines. Circulation 2022;146:e334-482. [Crossref] [PubMed]
5. Ma WG, Chen Y, Chen SW, et al. Frozen elephant trunk for acute type A aortic dissection: long-term outcomes over two decades. Eur Heart J 2026;47:2452-65. [Crossref] [PubMed]
6. Dai L, Zhao R, Yu C. A Modified Frozen Elephant Trunk for DeBakey Type I Aortic Dissection Patient: Sutureless Integrated Stented Graft. Eur J Vasc Endovasc Surg 2022;63:664. [Crossref] [PubMed]
7. Chang Q, Tian C, Wei Y, et al. Hybrid total arch repair without deep hypothermic circulatory arrest for acute type A aortic dissection (R1). J Thorac Cardiovasc Surg 2013;146:1393-8. [Crossref] [PubMed]
8. Zhang L, Yu C, Yang X, et al. Hybrid and frozen elephant trunk for total arch replacement in DeBakey type I dissection. J Thorac Cardiovasc Surg 2019;158:1285-92. [Crossref] [PubMed]
9. Czerny M, Schoenhoff F, Etz C, et al. The Impact of Pre-Operative Malperfusion on Outcome in Acute Type A Aortic Dissection: Results From the GERAADA Registry. J Am Coll Cardiol 2015;65:2628-35. [Crossref] [PubMed]
10. Ge YY, Rong D, Ge XH, et al. The 301 Classification: A Proposed Modification to the Stanford Type B Aortic Dissection Classification for Thoracic Endovascular Aortic Repair Prognostication. Mayo Clin Proc 2020;95:1329-41. [Crossref] [PubMed]
11. Qiu J, Luo X, Wu J, et al. A New Aortic Arch Dissection Classification: The Fuwai Classification. Front Cardiovasc Med 2021;8:710281. [Crossref] [PubMed]
12. Mikich B. Dissection of the aorta: a new approach. Heart 2003;89:6-8. [Crossref] [PubMed]
13. Matalanis G, Ip S. Total aortic repair for acute type A aortic dissection: a new paradigm. J Vis Surg 2018;4:79. [Crossref] [PubMed]
14. Yang B, Rosati CM, Norton EL, et al. Endovascular Fenestration/Stenting First Followed by Delayed Open Aortic Repair for Acute Type A Aortic Dissection With Malperfusion Syndrome. Circulation 2018;138:2091-103. [Crossref] [PubMed]
15. van Bakel PAJ, Henry M, Kim KM, et al. Imaging features of renal malperfusion in aortic dissection. Eur J Cardiothorac Surg 2022;61:805-13. [Crossref] [PubMed]