Acute type B aortic dissection (TBAD) with malperfusion syndrome (MS) poses a serious complication [1], involving the dynamic or static obstruction of branch arterial flow, leading to end-organ dysfunction and ischemia [2]. It represents a significant adverse risk factor for survival [3-8], necessitating prompt intervention in cases of sustained end-organ hypoperfusion. Open surgical repair has traditionally been the mainstay of treatment and recent years have seen substantial improvements in outcomes. However, identifying all arteries with malperfusion can be challenging during surgery [3,9]. Recently, endovascular treatment for complicated aortic dissection (AD) and TBAD with MS has shown significantly improved in-hospital survival rates compared with open surgical repair, as indicated by several studies [9-12]. The endovascular approach for TBAD with MS is useful for detecting compromised arteries and dynamic changes during the procedure. Consequently, endovascular treatment of TBAD with MS has become common. However, most reports have focused on short-term clinical outcomes, with limited data available on midterm outcomes, particularly in Asia.

Therefore, this study aimed to assess the clinical outcomes of endovascular treatment for acute TBAD with MS.

1) Study design and patient selection

The study was approved by the Institutional Review Board of the Pusan National University Hospital (No. PNUH 2021-0342) and the written informed consent was obtained from the patient.

This retrospective, single-center study focused on acute TBAD with MS, managed using an endovascular approach. We enrolled 27 patients admitted to our hospital between December 2009 and May 2020. Malperfusion syndrome was diagnosed based on clinical, biological, and/or radiological findings according to specific criteria: (1) renal malperfusion; oliguria/anuria accompanied by rising blood creatinine and blood urea nitrogen levels and/or a decrease in renal arterial blood flow observed on computed tomography (CT) scans, (2) visceral malperfusion; acute intractable abdominal pain exceeding expectations based on physical examinations, bowel tract bleeding, elevated lactate levels, and/or lack of enhancement of the bowel wall on CT scans, (3) iliofemoral malperfusion; symptoms include cool limbs, absent pulse, claudication, paresthesia, paralysis, and/or low flow in the iliac arteries.

Patients meeting any of the exclusion criteria were excluded from the analysis, including: (1) AD in the ascending aorta and aortic arch; (2) patients managed with debranching operation or other hybrid operation.

Preoperative CT scans were used to confirm the location of malperfusion, dynamic compression, or obstruction of the true lumen, and to rule out other diseases that could cause similar symptoms. Interventions for radiographic malperfusion without clinical correlation were not performed. The endpoint of the study was to evaluate all-cause death and reintervention rates. Procedure-related complications were analyzed, including stroke, paraplegia, cardiac events, limb ischemia, acute kidney injury (AKI), defined as a creatinine increase exceeding 1.5 mg/dL, and temporary or permanent renal replacement therapy (RRT) during hospitalization and the follow-up period.

2) Procedure

Thoracic endovascular aortic repair (TEVAR) was performed to facilitate aortic remodeling and restore blood flow in the aorta and its branches. Aortograhy was followed 10 minutes after TEVAR. Persistently compromised arteries after TEVAR were managed using a selective stenting strategy in the celiac, superior mesenteric, renal, and iliofemoral arteries. Selective stenting alone was chosen as the primary strategy in cases where TEVAR was not a viable option. For example, when both femoral arteries were compromised by AD and emerged from the false lumen, stenting was exclusively used.

TEVAR was done through the femoral artery that arose from a true lumen. The 7-French-long sheaths were inserted into the femoral arteries and the true lumen was confirmed by using angiography with a long sheath. A stent graft was advanced to cover the intimal tear (Fig. 1). We prefer to use taper-type stent grafts to adjust the size of the aorta and avoid post-balloon dilatation to reduce the risk of additional intimal tears, except in cases of type 1 endoleaks. The oversizing rates of the stent grafts were about 5%-10% relative to the diameter of the preserved aorta. After TEVAR, aortography and selective angiography of the visceral, renal, and iliofemoral arteries were performed to detect the persistently compromised arteries. Compromised arteries were defined as arteries with absence of blood flow or slow blood flow. The selective blood pressure of the branch arteries was checked using 4-French catheter in cases where it was equivocal. After confirmation of compromised arteries, selective stenting with bare-metal stents was performed.

Figure 1. Thoracic endovascular aortic repair for malperfusion syndrome. (A) Left femoral artery was punctured but, left common iliac artery was collapsed (white arrow). (B) Descending thoracic aorta was divided into true lumen and false lumen by intimal tear (Black arrow). (C) True lumen was expanded after stent graft deployment. (D) Blood flow of both common iliac arteries was restored.

In cases where TEVAR was difficult or at high risk, we performed isolated selective stenting for the compromised arteries without TEVAR. Selective stentings were performed with bare-metal stents using a renal guiding catheter for the celiac trunk, superior mesenteric artery, and renal artery. Stents were inserted across the false lumen from the true lumen to the compromised arteries like a bridge (Fig. 2). We used balloon-expandable and self-expanding stents based on the lesion length.

Figure 2. Selective stenting for malperfusion syndrome. (A) Left renal artery (black arrow) and celiac trunk were compromised (white arrow). (B) Left renal artery stenting was done from true lumen to renal artery across false lumen. (C, D) Stent was inserted in the celiac trunk and the blood flow of celiac trunk is restored. (E, F) Malperfusion at the right common iliac artery was managed with self-expanding stent.

3) Clinical and imaging follow-up

Patients underwent regular follow-up appointments at 1, 3, 6, and 12 months after the procedure, followed by subsequent visits every 6 months at outpatient clinics to assess their clinical status and identify complications. CT scans were conducted 1 week post-procedure, followed by imaging assessments at 1, 3, 6, and 12 months, and annually thereafter. These scans were performed to detect signs of endoleaks or alterations in the aorta and its branches. We also analyzed the occurrence of occlusion, kinking, or migration of the stent grafts and stents in the follow-up CT scans.

4) CT measurements

In this study, we compared CT scans obtained at 1 month and 3 years to assess changes in the aorta, true lumen, and false lumen of patients who underwent different treatments. CT scans were analyzed according to two groups. The two groups were those underwent TEVAR, either alone or with selective stenting (TEVAR group, 77.8%), and those who underwent selective stenting only for compromised branch arteries (Selective stenting group, 22.2%).

We measured the changes in the aortic area, true lumen area, and false lumen diameter at 3 levels: the renal artery, celiac trunk, and middle of the lesion (Fig. 3).

Figure 3. Measurement of true lumen area and false lumen diameter.

5) Statistical analysis

All parameters were described as the mean±standard deviation or frequency and percentage. Overall survival rate and reintervention-free survival analyses were performed using the Kaplan-Meier method. The parameters from the CT scans were analyzed using Student t-test and the Mann-Whitney U-test. Statistical analyses were performed using SPSS software (IBM SPSS Statistics version 22.0; IBM).

1) Study population

The baseline characteristics of the patients are summarized in Table 1. The mean age was 54.0±14.0 years, with 25 patients being men (92.6%). On admission, the mean systolic blood pressure was 155.1±31.6 mmHg, and there were no cases of hypotension or shock. Seventeen patients had a history of hypertension (63.0%) and 18 patients were current smokers (66.7%). Five patients had renal insufficiency (18.5%) before the procedure, five had lung disease (18.5%), and four had combined coronary artery disease (14.9%).

Table 1 . Demographic information of acute TBAD with MS managed with endovascular procedures.

Characteristics	Value
Age (y)	54.4±14
Men	25 (92.6)
BMI (kg/m2)	24.4±4.7
SBP on admission (mmHg)	155.1±31.6
DBP on admission (mmHg)	90.6±21.4
shock on admission	0 (0)
Biomarkers
WBC (/µL)	11,133.3±3,274.2
Hemoglobin (g/dL)	13.6±2.1
BUN (mg/dL)	24.4±18.6
s-Cr (mg/dL)	1.7±2.2
GFR (MDRD) (mL/min/1.73m2)	69.5±39.9
C-reactive protein (mg/dL)	2.9±5.4
Comorbidities
Hypertension	17 (63.0)
Diabetes mellitus	2 (7.4)
Dyslipidemia	2 (7.4)
Cerebrovascular accident	1 (3.7)
Renal insufficiency (baseline s-Cr>1.5 mg/dL)	5 (18.5)
Coronary artery disease	4 (14.8)
Peripheral artery disease	2 (7.4)
Smoking	18 (66.7)
Lung disease	5 (18.5)
Total	27 (100)

Values are presented as number (%), or mean±standard deviation..

TBAD, type B aortic dissection; MS, malperfusion syndrome; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; WBC, white blood cell count; BUN, blood urea nitrogen; GFR, glomerular filtration rate; MDRD, modification of diet in renal disease; s-Cr, serum creatinine.

2) Characteristics of aortic dissection and procedural data

Table 2 summarizes the characteristics of AD and procedural details. All 27 patients (100 %) presented with Stanford type B AD. A total of 12 patients exhibited renal artery malperfusion (44.4%) and 6 patients had malperfusion affecting more than two compromised branch arteries (22.2%). The mean duration from admission to the procedure was 5.5±7.9 days. Seven patients (25.9%) underwent TEVAR only, 6 patients (22.2%) underwent selective stenting only for compromised branch arteries, and 14 patients (51.9%) received combined endovascular treatment with TEVAR and selective stenting. A total of 17 patients underwent the procedure under local anesthesia (63.0%), whereas 10 patients underwent the procedure under general anesthesia (37.0%). Primary technical success was defined as graft deployment without type I or III endoleaks and the absence of open surgical conversion or death within 24 hours of the procedure, which was achieved in 26 patients (96.3%).

Table 2 . Charateristics of acute TBAD with MS managed with endovascular procedures.

Characteristic	Value
Arteries of malperfusion
Visceral	2 (7.4)
Renal	12 (44.4)
Iliofemoral	7 (25.9)
Combined (more than 2)	6 (22.2)
Visceral+renal	2 (7.4)
Renal+iliofermoral	2 (7.4)
Visceral+renal+iliofemoral	2 (7.4)
Duration from admission to procedure (d)	5.5±7.9
Type of procedure
TEVAR only	7 (25.9)
Selective stenting only	6 (22.2)
Combined procedure (TEVAR and selective stenting)	14 (51.9)
Anesthesia
General	10 (37.0)
Local	17 (63.0)
Primary technical success	27 (100)
Total	27 (100)

Values are presented as number (%) or mean±standard deviation..

TBAD, type B aortic dissection; MS, malperfusion syndrome; TEVAR, thoracic endovascular aneurysm repair..

3) Clinical outcomes

The in-hospital and long-term clinical outcomes were summarized in Table 3.

Table 3 . Clinical outcomes of endovascular treatment for acute TBAD with MS.

In hospital clinical outcome (n=27)	Value	Long term clinical outcomea (n=27)	Value
Mean length of hospital stay (d)	19.6±11.1	Mean follow up duration (y)	4.3±3.1
Major adverse events		Major adverse events
Death	0 (0.0)	Death	0 (0.0)
Stroke	2 (7.4)	Stroke	3 (11.1)
Minor	1 (3.7)	Maintenance HD	2 (7.4)
Major	1 (3.7)	Cardiac event	0 (0)
AKI	7 (25.9)	Aneurysmal change	1 (3.7)
Temporary RRT	3 (11.1)	Endoleak	1 (3.7)
Paraplegia	0 (0.0)	Reintervention rate	2 (7.4)
Cardiac event	0 (0.0)
Limb ischemia	1 (3.7)
Endoleak	1 (3.7)
Reintervention rate	1 (3.7)

^aLong term clinical outcome included in-hospital clinical outcome..

Values are presented as number (%) or mean±standard deviation..

TBAD, type B aortic dissection; MS, malperfusion syndrome; AKI, acute kidney injury;.

RRT, renal replacement therapy; HD, hemodialysis..

① In-hospital clinical outcomes

The mean hospitalization period was 19.6±11.1 days, and there were no deaths during hospitalization. Postprocedural stroke occurred in 2 patients (7.4%), consisting of one minor stroke and one major stroke. Both stroke cases were diagnosed using magnetic resonance imaging and were attributed to embolisms. Seven patients experienced AKI (25.9%), defined as a creatinine increase >1.5 mg/dL, and 3 patients required temporary RRT (11.1%). One patient eventually transitioned to permanent hemodialysis (HD) due to end-stage renal failure resulting from ischemia of both kidneys despite endovascular treatment of the compromised renal arteries. Additionally, one patient developed an insignificant type 1 endoleak after TEVAR, which resolved during follow-up. Critical limb ischemia occurred in 1 patient (3.7%), leading to reintervention 5 days after TEVAR. The left common iliac artery arising from the false lumen was compromised after TEVAR. A self-expanding bare-metal stent was inserted into the left common iliac artery using a contralateral approach.

② Long-term clinical outcomes

The mean follow-up period was 4.3±3.1 years, during which there were no deaths. One patient experienced a stroke (3.7%) during follow-up, and another patient initiated maintenance hemodialysis. The latter patient commenced hemodialysis 4 years after the procedure due to the progression of hypertensive chronic kidney disease. One patient required reintervention due to a new entry tear induced by the stent graft, resulting in an 80 mm aneurysmal change in the descending aorta below the stent graft, occurring 5 years after TEVAR and selective stenting into the celiac trunk and renal artery. An additional stent graft was deployed to cover the aneurysmal changes in the descending aorta below the initial stent graft. During follow-up CT scans, no occlusion, kinking, or migration of the stent grafts or bare metal stents was observed in patients who underwent TEVAR and selective stenting. Furthermore, there were no conversions to open repair or deaths. Procedure-related complications occurred in 2 patients who required reintervention (Table 3). The cumulative death or reintervention-free survival rates at 1 month, 1 year, and 5 years were 96.3%, 96.3%, and 92.6%, respectively, according to the Kaplan-Meier curve (Fig. 4).

Figure 4. Kaplan-Meier analysis of cumulative death or reintervention-free survival. TEVAR, thoracic endovascular aortic repair.

4) Comparative analysis of CT scans

In this study, we conducted a comparative analysis of CT scans obtained at 1 month and 3 years to evaluate changes in the aorta, true lumen, and false lumen of patients who received different treatments. We categorized patients into two groups based on their history of treatment. Specifically, we assessed the changes in the aortic area, true lumen area, and false lumen diameter at 3 levels: the renal artery, celiac trunk, and middle of the lesion (Fig. 3). When comparing the Selective stenting group and the TEVAR group, we observed a significant increase in the changes of aortic area at the middle of the lesion (TEVAR group: 188.4±543.9 mm² vs. Selective stenting group: 878.9±436.3 mm², P=0.037), at the celiac trunk level (TEVAR group: 22.8±179.7 mm² vs. Selective stenting group: 303.7±45.1 mm², P=0.025), and at the renal artery level (37.3±165.5 mm² vs. 442.9±100.9 mm², P=0.019) (Table 4).

Table 4 . CT parameters between TEVAR group and Selective stenting group.

	TEVAR group (n=21)	Selective stenting group (n=6)	P-value
Measurement at the middle of lesion
Change of aortic area	188.4±543.9	878.9±436.3	0.037
Change of true lumen area	353.6±337.7	320.2±452.1	0.946
Change of false lumen diameter	–7.1±7.2	10.4±19.4	0.059
Measurement at the celiac trunk level
Change of aortic area	22.8±179.7	303.7±45.1	0.025
Change of true lumen area	136.9±119.5	46.6±60.8	0.026
Change of false lumen diameter	–3.5±7.4	11.0±5.4	0.013
Measurement at the renal a level
Change of aortic area	37.3±165.5	442.9±100.9	0.019
Change of true lumen area	57.2±50.1	75.1±17.0	0.545
Change of false lumen diameter	–1.0±5.7	5.3±5.4	0.122

Values are presented as mean±standard deviation..

TEVAR, thoracic endovascular aneurysm repair..

There were significant increase in the change of true lumen area and decrease in the change of false lumen diameter in TEVAR group compared with Selective stenting group at the celiac trunk level (change of true lumen area; TEVAR group: 136.9±119.5 mm² vs. Selective stenting group: 46.6±60.8 mm², P=0.026, change of false lumen diameter; TEVAR group: –3.5±7.4 mm² vs. Selective stenting group: 11.0±5.4 mm², P=0.013).

Malperfusion is a potentially lethal complication of acute TBAD, occurring in 10%-33% of TABD patients [2]. End-organ malperfusion is a catastrophic condition with adverse outcomes. Patients with complicated TBAD that manifests as renal or mesenteric ischemia have high operative mortality rates of 50% and 88%, respectively [13,14]. Conventional treatment for MS remains controversial, and several concerns remain. The International Registry of Acute Dissection published data indicating that endovascular treatment may result in lower in-hospital mortality rates for patients with complicated acute TBAD than surgical repair (10.6% vs. 33.9%, P=0.002) [15]. Zeeshan et al. [16] reported that TEVAR was associated with lower in-hospital or 30-day mortality rates than conventional therapy (open surgical repair and medical therapy) in patients with acute complicated TBAD (4% vs. 40% vs. 33%, P=0.006). In addition, the group that underwent TEVAR showed significantly improved survival rates at 1, 3, and 5 years (82%, 79%, and 79% vs. 58%, 52%, and 44%, respectively; P=0.008). In our study, no deaths occurred during hospitalization or follow-up in patients with acute TBAD with MS who underwent endovascular treatment. Despite the lack of randomized analyses comparing open repair and endovascular treatment, the efficacy of endovascular treatment for acute TBAD with MS has resulted in good clinical outcomes.

In our series, all procedures were performed on patients with acute TBAD with MS and primary technical success was achieved in all the patients. The average time from admission to procedure was 5.5±7.9 days. However, in cases where malperfusion worsened, the procedures were performed as soon as ischemic findings were present. In general, endovascular treatment is technically easier than surgery for patients with acute TBAD with MS because it is difficult to detect arteries with malperfusion during surgery. Additionally, endovascular treatment can reduce the procedure time compared to surgery. For the management of acute TBAD with MS, we used TEVAR only in 25.9% of cases, selective stenting only for compromised arteries in 22.2% of cases, and a combination of TEVAR and selective stenting in 51.9% of cases. TEVAR is the preferred method for inducing aortic remodeling. However, in some cases, the compromised arteries remain without blood flow after TEVAR. In these instances, additional selective stenting of the compromised arteries was performed. The predictors influencing blood flow restoration in compromised arteries after TEVAR are unclear; as of writing, there were no research articles on predictors of blood flow restoration. Many factors, including the status of the dissection flap, entry site, re-entry sites, and pressure of the false lumen, may influence the remaining compromised arteries after TEVAR. Therefore, it is important to perform a meticulous search to detect the arteries compromised by AD after TEVAR. Selective stenting for compromised arteries was performed across the false lumen from the true lumen to the compromised arteries with bare metal stents. We used balloon-expandable and self-expanding stents based on the lesion length.

Complications occurred mostly in hospital settings (Table 3), with the most common complications being AKI due to compromised aorta and renal arteries, and contrast-induced renal injuries. AKI occurred in seven patients (25.9%). RRT was required in 3 of the 7 patients (11.1%), which was temporary in two patients, but one patient inevitably switched to permanent HD. During follow-up, one patient started maintenance HD after 4 years because of worsened hypertensive chronic renal failure. Early stroke developed in approximately 7.4% (one minor stroke and one major stroke) of the patients. Afifi et al. [17] reported early complications (defined as events occurring within 30 days) in patients who underwent open repair and TEVAR for complicated TBAD. The authors reported the occurrences of AKI (30.8% vs. 37.8%), AKI requiring dialysis (15.4% vs. 5.4%), and stroke (1.9% vs. 8.1%). Moulakakis et al. [18] reported a cerebrovascular event rate of 6.8% in patients with complicated TBAD treated with open surgical repair. Stroke occurs more frequently after endovascular treatments. This may be attributed to the advancement of large-profile stent grafts in the aorta, potentially compromising the carotid and left subclavian arteries through the false lumen. One patient exhibited an insignificant type 1 endoleak after TEVAR, which resolved during follow-up, and another required reintervention with a bare metal stent due to limb ischemia during hospitalization. However, conversion to open repair was not observed. Subsequently, one patient required reintervention due to an aneurysmal change (aneurysm size: 80 mm) in the aorta below the stent graft, occurring 5 years after TEVAR and selective stenting into the celiac trunk and renal artery.

According to the study of Afifi et al. [17], aortic reintervention was necessary in 10.8% of complicated TBAD cases treated with TEVAR, whereas 15.3% required reintervention in the surgical group. In our study, reinterventions were associated with a compromised iliac artery after TEVAR and AD progression, leading to aneurysmal changes at the distal end of the stent graft. Fortunately, we did not observe any cord injuries.

Previous reports have suggested that TEVAR induces favorable remodeling of the aorta during follow-up, characterized by an increase in true lumen size and a decrease in false lumen size along the dissected aorta [19,20]. However, data on aortic remodeling in patients managed solely with selective stenting for compromised branch arteries without TEVAR are limited. In our CT data, we observed a significant increase in the changes in the aortic area at the middle of the lesion in the selective stenting group compared to that in the TEVAR group. There was a significant increase in the change in true lumen area and a decrease in the change in false lumen diameter in the TEVAR group compared to the selective stenting group at the celiac trunk level. The TEVAR group demonstrated a favorable effect on aortic remodeling compared with the selective stenting group, as TEVAR protected blood flow into the false lumen. In cases of selective stenting only for compromised branch arteries without TEVAR, the increase in aortic size could be related to the leakage of blood into the false lumen through bare-metal stents. Therefore, TEVAR should be considered the first-line treatment, with subsequent selective stenting for compromised branch arteries, as necessary. Selective stenting alone was chosen as the primary strategy in cases where TEVAR was not a viable option. However, the significant change of aortic area and increase of false lumen diameter were observed compared with TEVAR group; therefore meticulous follow-up is necessary for this group of patient.

Our study had several limitations. First, this was a single-center, retrospective, observational study with a small cohort, which limited our ability to conduct additional statistical analyses, requiring a larger sample size. Second, the absence of a randomized study comparing endovascular treatments with surgical repairs prevents direct comparison with open repairs. Third, we restricted our analysis to cases of AD occurring solely in the descending aorta to ensure clarity of interpretation. Cases involving AD of the ascending aorta and aortic arch in which patients underwent debranching operations or other hybrid procedures were excluded from the analysis. Consequently, our study was evaluated descriptively owing to its small sample size. Nonetheless, our findings demonstrate clinical outcomes comparable to those reported in recently published studies.

Endovascular treatment for acute TBAD with MS has demonstrated a high primary technical success rate and favorable clinical outcomes, suggesting that it is a potential alternative treatment option. However, further randomized studies comparing endovascular treatment with surgical intervention are warranted to provide comprehensive insight into their efficacy and safety.

This work was supported by clinical research grant from Pusan National University Hospital in 2022.

The authors have nothing to disclose.

Conception and design: HCL. Analysis and interpretation: all authors. Data collection: LEK, JHP, MJB, JHY. Writing the article: LEK, JHP, HCL. Critical revision of the article: HCL. Final approval of the article: HCL. Statistical analysis: HCL, LEK. Obtained funding: HCL. Overall responsibility: HCL.