Investigation of the Survival Time of Patients Who Underwent Endovascular Treatment Due to Type 3 Aortic Dissection and Factors Affecting This Duration

Abstract

Objective

This study aimed to analyze the survival time of patients who underwent thoracic endovascular aortic replacement (TEVAR) due to acute type 3 aortic dissection and to investigate comorbid conditions and dissection characteristics that affect survival time.

Materials and Methods

Between 2013 and 2023, 94 patients who underwent TEVAR for type 3 dissection were retrospectively investigated. Survival time and factors affecting this time (comorbidity and dissection characteristics) were analyzed.

Results

The most common comorbidities were hypertension (88%). There was no significant difference between the demographic data of surviving and deceased patients. During the follow-up period, 57% of the patients survived, and 43% of the patients died. The mean survival time after TEVAR was 20.1 (0–108) months among patients who died and 47.7 (2–120) months for patients who lived. The mean number of comorbidities was 2.13 in patients who died and 2.25 in patients who survived. Survival distribution according to the type of interventional procedure was 50% for partial closure of the subclavian artery, 38.1% for complete closure, and 66.2% for closure starting from the distal subclavian artery ( p  = 0.06). Survival rate was significantly higher in patients who underwent reintervention ( p  = 0.005). Mortality was 9.5% in the early period, 25.5% in the first year, 29.7% in the second year, 34% in the third year, and 39.3% in the first 5 years.

Conclusion

In our study, the survival rate was higher in patients who were followed regularly, and reintervention was applied when necessary. Therefore, we believe that undetected or untreated complications after TEVAR, rather than comorbid conditions, negatively affect survival more.

The incidence of Stanford type B or De Bakey Type 3 (Type 3) aortic dissection is thought to be 3 to 4 per 100,000 person-years. ^{1 2} Type 3 aortic dissections are important and should be treated because of serious complications, including rupture, aneurysm formation, and malperfusion syndromes. However, debate continues regarding the timing of treatment.

Thoracic endovascular aortic repair (TEVAR) provides blood flow to the true lumen by closing the intimal tear; thereby promoting thrombosis of the false lumen and finally contributing to the stabilization of the vessel wall. ^{3 4 5 6 7 8} This process may decrease the mortality rate up to 14% by reducing aneurysm development and the risk of rupture. ³ If reentry points persist after TEVAR, the true lumen is compressed, and malperfusion may occur. In such cases, the PETTICOAT (Provisional Extension to Induce Complete Attachment) technique can be applied with a specially designed bare stent after placement of the proximal covered stent. ⁹

The aim of this study was to analyze the survival of patients who underwent TEVAR due to acute type 3 dissection and to investigate the comorbid conditions (hypertension, diabetes, end-stage renal disease, malignancy, chronic lung disease, etc.) and dissection characteristics (dissection zone, need for reoperation, and types of procedures performed) affecting the survival duration.

Materials and Methods

Between October 2013 and July 2023, patients who underwent TEVAR due to acute (<14 days) type 3 dissection in our clinic were retrospectively analyzed. Inclusion criteria for the study were patients with an aortic diameter of ≥45 mm, a false/true lumen ratio of 0.7 or higher, ongoing pain complaints, and complicated aortic dissection. Exclusion criteria: De Bakey type 1 and type 2 patients, patients with ruptured type 3 dissection, patients with traumatic dissection, and patients with type 3 dissection in the subacute and chronic stages were excluded from the study. De Bakey Type 1 (Stanford Type A) aortic dissection: Involvement of any segment of the aorta together with the aortic arch, Type 2 (Stanford Type A) aortic dissection: Involvement of the isolated ascending aorta, Type 3 (Stanford Type B) aortic dissection: Involvement of the descending aorta only.

Information about the patients was obtained from the hospital software system, medical records, death notification system, radiological images, and reports. Approval for the study protocol was obtained (2024/4791) from the Local Ethics Committee of our faculty, and written informed consent was obtained from each patient. The study was conducted in accordance with the principles of the Declaration of Helsinki.

Patients were divided into three groups according to the surgical procedure performed: (1) Partial closure of the subclavian artery, (2) Total closure of the subclavian artery, and (3) TEVAR starting from the distal subclavian artery with no closure of the subclavian artery. Lifetech (Ankura TAA Stent Graft System, Shenzhen, China) and Medtronic (Valiant Thoracic Stent Graft, Captiva Delivery System, Ireland) brand aortic endovascular covered stents were used for the procedures. Invamed Stena grafts (Stent System Peripheral Modulator Flow Diverter, Türkiye) were used as bare stents.

Age, gender, comorbid conditions (diabetes, hypertension, chronic obstructive pulmonary disease [COPD], coronary artery disease, chronic renal failure, malignancy, hypertrophy, atrial fibrillation, peripheral arterial disease, and gastrointestinal diseases), life expectancy, brands of aortic stents used, zone of dissection, types of surgical procedures performed, need for reoperation, and time of reoperation were analyzed. The relationship between comorbidities, type of intervention, dissection characteristics, and survival was analyzed.

Surgical Method

Computerized tomography angiography (CTA) was used for diagnosis and preoperative planning of the patients. The vessel diameters, course of the vessels in terms of tortuosity, true–false lumen differentiation, and the location of the access tear were evaluated before intervention. General anesthesia was preferred for the surgical procedure. Both groin areas were prepared for femoral artery access. Vascular structures were evaluated with preoperative USG. Single-leg femoral artery exploration was performed according to the preoperative CTA evaluation. A 7F catheter was placed in the contralateral femoral artery for imaging. Imaging was obtained by advancing a pigtail catheter proximal to the dissection with a 0.35 hydrophilic guide wire. After confirmation of the true lumen, the TEVAR stent graft, which was previously measured and prepared for the patient, was implanted over the super stiff wire. Patients in whom the dissection line was thought to extend to zone 2, the left subclavian artery was covered distal to the left common carotid artery ( Fig. 1 ). In dissections involving zone 3 levels, the left subclavian artery was partially covered ( Fig. 2 ) or left intact ( Fig. 3 ). The pigtail was then advanced through the TEVAR stent graft over the hydrophilic wire and a control image was obtained. Meanwhile, the dissection image was interpreted, and it was evaluated whether the patient needed an additional stent. As a general approach, the TEVAR stent graft was extended to cover the rupture point (reentry) in patients in whom the dissection line continued distal to the stent, and the second intimal tear imaging was confirmed. A follow-up decision was made in patients without an intimal tear. At this time, a maximum of 10% of oversized was performed. TEVAR procedures never extended distally to the celiac artery and lower. In the first procedure, a covered stent was placed proximally. In case of the need for an additional stent distally, if there was a branch leaving the aorta in the area to be stented, a bare stent was added (PETTICOAT technique; Figs. 2 , 4 ); if not, a covered stent was added ( Fig. 3 ). In reinterventions, covered or bare stents were used again according to the presence of aortic branch. Left subclavian artery revascularization was performed in the presence of postoperative ischemia findings (discoloration, coldness, pallor, pulselessness).

Fig. 1.

Images of a type 3 dissection patient in which the left subclavian artery was completely covered. LCCA, left common carotid artery; LSA, left subclavian artery.

Fig. 2.

Image of the case in which the left subclavian artery was partially covered (covered stent was placed in the proximal, bare stent was placed in the distal).

Fig. 3.

Images of the case in which a stent was placed starting from the distal part of the left subclavian artery (two consecutive covered stents). CT image ( A ), 3D image ( B ).

Fig. 4.

Two- and three-dimensional images of a type 3 dissection patient in whom covered and bare stents were placed sequentially (PETTICOAT technique). CT image ( A ), 3D image ( B ). PETTICOAT, Provisional Extension to Induce Complete Attachment.

Statistical Method

Mean and standard deviation are given for numerical variables, and frequency and percentage descriptive statistics are given for categorical variables. The t -test was used to compare numerical variables, and chi-square or Fisher's exact tests were used to analyze categorical variables. Logistic regression and survival analyses were performed to find variables associated with death. Analyses were performed with the R 4.3.2 (R Core Team, 2024) program. p- Value <0.05 was considered significant.

Results

Of the 94 patients included in the study, 78 (83%) were male and 16 (17%) were female. The mean age was 59.68 ± 14.06 years. Nineteen (20.2%) patients had type 3A dissection (above the level of the diaphragm) and 75 (79.7%) patients had type 3B dissection (below the level of the diaphragm). The number of patients who survived during the follow-up period was 54 (57%), and the number of patients who died was 40 (43%). The mean survival time after TEVAR was 20.1 (0–108) months in deceased patients and 47.7 (2–120) months in living patients. The mean number of comorbidities was 2.13 in deceased patients and 2.25 in surviving patients. Comorbid conditions and their frequency are given in Table 1 .

Table 1. Comorbid situations.

Variable	N  = 94, (percentage)
Hypertension	83 (88%)
Diabetes	15 (16%)
Chronic obstructive pulmonary disease	18 (19%)
Coronary artery disease	12 (13%)
End-stage renal disease	7 (7.5%)
Malignancy	2 (2.1%)
Gastrointestinal disease	3 (3.2%)
Hyperthyroidism	6 (6.4%)
Peripheral artery disease	3 (3.2%)
Atrial fibrillation	3 (3.2%)

There was no statistically significant difference when the demographic data of surviving and deceased patients were compared ( Table 2 ). When comparing the intervention types of surviving and deceased patients, a trend toward statistical significance was detected ( p  = 0.06).

Table 2. Comparison of demographic characteristics of deceased and surviving patients.

Variable	Dead, N  = 40 a	Alive, N  = 54 a	p -Value b
Age	58.93 ± 16.76	60.24 ± 11.81	0.67
Sex			0.22
Male	31 (78%)	47 (87%)
Female	9 (23%)	7 (13%)
Hypertension	35 (88%)	48 (89%)	> 0.99
Diabetes	7 (18%)	8 (15%)	0.73
Hypertension + Diabetes	4 (10%)	7 (13%)	0.75
Chronic obstructive pulmonary disease	8 (20%)	10 (19%)	0.86
Coronary artery disease	6 (15%)	6 (11%)	0.58
End stage renal disease	5 (13%)	2 (3.8%)	0.14
Malignancy	1 (2.5%)	1 (1.9%)	> 0.99
Gastrointestinal disease	1 (2.5%)	2 (3.7%)	> 0.99
Hyperthyroidism	1 (2.5%)	5 (9.3%)	0.24
Peripheral artery disease	1 (2.5%)	2 (3.7%)	> 0.99
Atrial fibrillation	1 (2.5%)	2 (3.7%)	> 0.99

^a Mean ± standard deviation; n (%).

^b Welch's two-sample t -test; Pearson's chi-square test; Fisher's exact test.

The survival rate was found to be significantly higher in patients who underwent reintervention ( p  = 0.005). No significant difference was found when comparing dissection types (3A or 3B) in terms of survival ( p  = 0.32). In the univariate and multivariate logistic regression analyses of categorical variables, a significant difference was found in patients who underwent reintervention ( p  = 0.002), while a near-significant difference ( p  = 0.06) was obtained from comparison of intervention types, but no significant difference was detected for other variables. Comparison information about the dissection characteristics of deceased and surviving patients is given in Table 3 . Procedure type and survival information for Type 3A and Type 3B dissection patients are given in Table 4 .

Table 3. Comparison of dissection characteristics of deceased and surviving patients.

Variable	Dead, N  = 40 a	Alive, N  = 54 a	p -Value b
Interventional procedure type			0.069
1. TEVAR with partial closure of the subclavian artery	7 (50%)	7 (50%)
2. TEVAR with total occlusion of the subclavian artery	13 (62%)	8 (38%)
3. TEVAR starting from the distal subclavian artery	20 (34%)	39 (66%)
Reintervention			0.005
No  Yes	37 (49%) 3 (17%)	39 (51%) 15 (83%)
Dissection types
A  B	9 (47%) 30 (40%)	10 (53%) 45 (60%)	0.32

Abbreviation: TEVAR, thoracic endovascular aortic replacement.

^a Mean ± standard deviation; n (%).

^b Welch's two-sample t -test; Pearson's chi-square test; Fisher's exact test.

Table 4. Procedure type and survival information for Type 3A and Type 3B dissection patients.

Dissection type	Subclavian partial ( N  = 14)	Subclavian total ( N  = 21)	Subclavian distal ( N  = 59)
Type A ( N  = 19)
Lives: 53% Dead: 47%	2 dead	2 dead	10 lives 5 dead
Type B ( N  = 75)
Lives: 59% Dead: 41%	7 lives 5 dead	8 lives 11 dead	29 lives 15 dead

The type of interventional procedure was TEVAR with partial closure of the subclavian artery in 15% ( n  = 14), TEVAR with total closure of the subclavian artery was performed in 22% ( n  = 21) of patients, and TEVAR starting from the distal subclavian artery was performed in 63% ( n  = 59). Of patients, 15.9% ( n  = 15) required additional stents distally during the first procedure. Of the stents used, eight were covered stents and seven were bare stents.

Stent graft brands and distribution used in TEVAR procedures were Lifetech Ankura in 32 patients and Medtronic Valiant in 62 patients. The distribution of patients who died according to stent graft type was 48.3% ( n  = 30/62) Medtronic Valiant and 31.2% ( n  = 10/32) Lifetech Ankura. Stent grafts of various sizes (20–46 mm; 14–46 mm; 60–200 mm) were used.

Survival distribution according to the type of interventional procedure was as follows: 50% ( n  = 7) survival and 50% ( n  = 7) death in cases with partial closure of the subclavian artery, 38.1% ( n  = 8) survival and 61.9% ( n  = 13) death in cases with total closure of the subclavian artery, and 66.2% ( n  = 39) survival and 33.8% ( n  = 20) death in cases with closure starting from the distal subclavian artery. In the comparison of the types of intervention, a result close to statistical significance was found ( p  = 0.06; Table 3 ).

In the postprocedure follow-up, left subclavian artery revascularization (caroticosubclavian bypass with 7-mm PTFE ring graft) was performed in two patients due to ischemia findings in the left arm.

Eighteen patients required reintervention during follow-up. One of these patients underwent reintervention twice, and the others once each. The mean time to reintervention after the first procedure was 16.1 (1–60) months. Reasons for reintervention were distal aneurysm in four patients, distal TEVAR dissection in eight patients, type 1b endoleak in five patients, and abdominal aortic rupture in one patient. In patients requiring reintervention, the stent graft brand used in the first operation was Medtronic Valiant in 8 and Lifetech Ankura in 10 patients. The reoperation rate was 12.9% (8/62) for Medtronic Valiant grafts and 31.2% (10/32) for Lifetech Ankura grafts. During these procedures, 13 Medtronic covered stents, 3 Lifetech Ankura covered stents, 1 Invamed Stena bare stent, and 1 Medtronic Valiant abdominal aortic stent were used. Of the patients who underwent reintervention, 16.6% ( n  = 3) died and 83.4% ( n  = 15) survived.

The total number of patients who died was 40. Of the patients who died, 60% ( n  = 24) died within the first 12 months (9 patients within the hospitalization period, 9 patients within the first 3 months, 3 patients within the second 3 months, 3 patients within the second 6 months). Of patients who died, 10% ( n  = 4) died within the second 12 months, 10% ( n  = 4) patients died within the third 12 months, 12.5% ( n  = 5) patients died within the fourth and fifth 12 months, and the remaining 7.5% ( n  = 3) patients died at different times between 61 and 108 months. The mortality rate was 16.6% (3/18) in patients who underwent reintervention and 48.6% (37/76) in patients who did not undergo reintervention. This difference was found to be statistically significant ( p  = 0.005).

Discussion

Mortality in patients treated medically for uncomplicated acute type B dissection was reported to be 10% in the first 30 days, 20 to 40% in 5 years, and 60% in 10 years. ^{10 11} Early postoperative mortality of up to 10% was reported in patients undergoing TEVAR for thoracic aortic aneurysm and/or dissection, ¹² and early mortality of less than 5% was reported in patients undergoing TEVAR for chronic type B aortic dissection. ¹³ In acute complicated dissections, in-hospital mortality of TEVAR (10%) was superior to open surgery (34%). ¹⁴ In our study, the early mortality rate was 9.5%. The number of complicated patients was 11.7% (2 out of 11 patients died). No significant difference was found in terms of age, sex, and comorbid conditions in the comparison of survivors and deceased patients ( Table 2 ). The exact causes of death could not be determined for all cases. The presence of out-of-hospital deaths and the estimation of some causes of death prevented us from obtaining accurate data in this regard. In our study, the mortality rate in the first year was 25.5%, in the second year 29.7%, in the third year 34%, and in the first 5 years 39.3%.

It is reported in the literature that type 3 dissection patients are typically male, and the average age is between 58 and 65 years. ^{1 2 15 16} More than 80% of the cases have a history of hypertension and are accompanied by associated comorbidities such as diabetes, renal failure, chronic lung disease, and peripheral artery and coronary artery disease. ^{1 2 15} In our study, the gender distribution was 83% male and 17% female, and the mean age was 59.6 years. The most common comorbid conditions were hypertension with a prevalence of 88%, COPD with a prevalence of 19%, diabetes with a prevalence of 16%, and coronary artery disease with a prevalence of 13%. Other comorbid conditions were seen at rates below 10% (2.1–7%; Table 1 ).

Contrary to expectations, the mean number of comorbidities was higher in surviving patients (surviving patients: 2.25, deceased patients: 2.13). The mortality rate of patients who underwent reintervention was found to be significantly ( p  = 0.005) lower than those who did not undergo reintervention. Comparing survival according to intervention types, a trend toward statistical significance ( p  = 0.06) was found. In patients with partial closure of the subclavian artery, the mortality and survival rates were equal. The mortality rate was the highest at 61.9% in cases with total closure of the subclavian artery. In cases where the subclavian artery was not covered, the mortality rate was 38.1% (lowest). (As mentioned in the “Materials and Methods” section, the choice of intervention type was based on the dissection extension zone.) As a result of this study, the death rate with zone 2 level dissection is found to be higher than that of patients with zone 3 level dissection.

All these results lead to the conclusion that the cause of death was related to aortic dissection rather than comorbid conditions. Retrograde type A dissection occurring after TEVAR is one of the most feared complications because of its high mortality (up to 40% mortality). ¹⁷ In many studies, follow-up with radiological imaging is recommended for patients undergoing endovascular procedures at 1, 6, 12 months, and once a year (lifetime) in cases without complications. ^{18 19 20 21 22 23} In our study, the mortality rate was lower when reintervention was performed in patients with new aortic pathology after imaging.

It was observed that deaths were high in the early period ( n  = 21 in the first 6 months, n  = 3 in the second 6 months, n  = 4 in the second 12 months) and decreased over time. This may be related to stabilization of the aortic wall. Therefore, patients should be followed up for life and more frequently in the early post-TEVAR period (because 60% of patients died in the first 12 months, and 40% died between 13 and 108 months). We believe that regular follow-up and radiological imaging will reduce the mortality and morbidity associated with dissection.

There is an ongoing debate in the literature regarding the timing of TEVAR. In a study comparing acute (1–14 days) and subacute (15–90 days) groups, it was reported that 30-day mortality was five times higher in the acute group, and aortic rupture, retrograde type A dissection, and stroke were observed only in the acute group. ²⁴ The high mortality rate in our study may be related to TEVAR being performed in the acute phase.

The distribution of patients who died according to the grafts used was 48.3% Medtronic Valiant and 31.2% Lifetech Ankura. Reintervention rate was 12.9% for Medtronic grafts and 31.2% for Lifetech Ankura grafts. We believe that the difference in these results is due to unequal numbers of patients, differences in the organ fed from the false lumen, different levels of extension of the dissections, and the fact that not all patients were regularly checked, and imaging was not performed. Because of these reasons, it would not be meaningful to compare the effects of graft types on survival in terms of reaching accurate results.

There is an ongoing debate about prophylactic spinal drainage for endovascular treatment of type 3 dissections. ²⁵ The length of the graft to be placed and the origin of the Adamkiewicz artery are important. Although we did not perform spinal drainage in our cases, no clinical findings suggesting spinal cord ischemia were observed after the procedure. In this result, we think that the use of the PETTICOAT (coated stent + bare stent) method is effective in cases where a long stent is required.

There are some limitations to our study. These include being a retrospective study, the exact causes of death not being known, and the stent brands used not being of equal numbers.

In conclusion, in our study, the survival rate was higher in patients who were followed up regularly and underwent additional procedures when necessary. Therefore, we believe that complications related to the dissection itself and its management, rather than comorbid conditions, affect survival more. In addition, TEVAR in the acute phase may have increased mortality.