Impact of ascending aortic,hemiarch and arch repair on early and long-term outcomes in patients with Stanford A acute aortic dissection

Abstract

Background:

Stanford A acute aortic dissection (AAD) is a life-threatening emergency associated with major morbidity and mortality. The aim of this study was to compare outcomes of three different surgical approaches in patients with Stanford A AAD.

Methods:

From January 2006 to March 2015 a total of 240 consecutive patients with diagnosed Stanford A AAD underwent elective, isolated surgical aortic repair in our centre. Patients were divided into three groups according to the extent of surgical repair: isolated replacement of the ascending aorta, hemiarch replacement and total arch replacement. Patients were followed up for up to 9 years. After univariate analysis multinomial logistic regression was performed for subgroup analysis. Baseline characteristics and endpoints as well as long-term survival were analysed.

Results:

There were no statistically significant differences among the three groups in terms of demographics and preoperative baseline and clinical characteristics. Incidence of in-hospital stroke (p = 0.034), need for reopening due to bleeding (p = 0.031) and in-hospital mortality (p = 0.017) increased significantly with the extent of the surgical approach. There was no statistical difference in terms of long-term survival (p = 0.166) among the three groups. Applying multinomial logistic regression for subgroup analysis significantly higher odds for stroke (p = 0.023), reopening for bleeding (p = 0.010) and in-hospital mortality (p = 0.009) for the arch surgery group in comparison to the ascending aorta surgery group as well as significantly higher odds for stroke (p = 0.029) for the total arch surgery group in comparison to the hemiarch surgery group were identified.

Conclusions:

With Stanford A AAD the incidence of perioperative complications increased significantly with the extent of the surgical approach. Subgroup analysis and long-term follow up in patients undergoing isolated ascending or hemiarch surgery showed a lower incidence of cerebrovascular events compared with surgery for total arch replacement.

Keywords

aortic repair arch ascending aorta hemiarch outcomes Stanford A acute aortic dissection

Introduction

The aorta represents the main vessel extending from the left ventricle delivering pulsatile blood flow distally to organs and tissues.¹ If damaged in the fashion of Stanford A acute aortic dissection (AAD), a life-threatening emergency occurs associated with an exceptionally high mortality rate rising to 50% in the first 48 h after symptom onset, particularly in patients who are not immediately referred for surgical treatment to centres with expertise in this procedure.² Previous research reported on various surgical treatment modalities in patients with AAD aiming to reduce the risk of aortic rupture or extension of dissection by repairing either the isolated ascending aorta or in combination with the hemiarch or total arch depending on the extent of dissection. However, there is little evidence available on the advantages and disadvantages of each treatment type.^3–8 In particular, data on the most devastating complications and endpoints are scarce, especially on neurological outcomes and mortality.^9–11 Whereas a significant proportion of patients may survive this life-threatening condition, they may suffer from paralyzing ramifications of the stroke area. This does not only impact patients’ ability to perform daily activities but also impairs the whole patient’s social environment aside from additional financial stress. Due to the lack of data and with the aim of improving patients’ outcomes and quality of life there is high demand for focusing on the impact of the different surgical approaches on long-term neurological outcomes and mortality of patients suffering from AAD.

Moreover, though in consequence of the invasive nature of aortic surgery bleeding and the consecutive need for reopening represent frequent complications in the Stanford A AAD setting. Bleeding associated with a high need for transfusions has also been incompletely investigated. In particular, little research is available on the elevated need for red blood cells (RBC), fresh frozen plasma (FFP) and platelets in Stanford A AAD surgery.¹²

The aim of this study was to compare perioperative data and outcomes of three different surgical approaches in patients with Stanford A AAD with the view to improving patients’ selection for various surgical strategies with a special emphasis on mortality, neurological complications, bleeding complications and requirement of blood components.

Patients and methods

Study design

The study design was a retrospective analysis of collected registry data. The Institutional Review Board of Cologne University approved this study and waived the need for individual patient consent.

An analysis of all consecutive patients diagnosed with Stanford A AAD who were referred to our institution for emergent surgical treatment from January 2006 to March 2015 was performed with particular focus on the impact of the extent of surgical repair on early and long-term outcomes. After exclusion of patients who deceased prior to surgery, a total of 240 subjects remained in the present analysis. Patients were divided into three groups according to the extent of surgical repair. Ascending aorta repair was performed in 126 cases, hemiarch repair in 72 cases and total arch repair in 42 cases. Indication of aortic dissection was performed in accordance with current international guidelines.¹³ Contraindications were absence of patient’s consent as well as clinical and surgical limitations, such as severe neurological disorder or multiorgan failure.

Another analysis based on the patient cohort from the present report was published by our group elsewhere,^14,15 whereas all data sets are represented by routine parameters from our institution that did not constitute any additional burden for the patients. This article presents a separate study with different protocol and approval process from the above-mentioned study.

Primary endpoints were long-term overall cumulative survival and freedom from major cerebrovascular events up to 9 years of follow up. Secondary endpoints were early postoperative clinical characteristics and adverse events. Preoperative baseline demographics and characteristics as well as outcomes for the three different surgical approaches were compared initially using a univariate analysis. After univariate analysis, a multinomial logistic regression was performed for subgroup analysis of arch surgery in comparison to hemiarch and ascending aortic surgery, respectively. In order to address the impact of extent of surgery on long-term outcomes after three different surgical approaches, overall cumulative survival and survival free from major cerebrovascular events were presented.

Follow up was obtained through direct contact with patients and patients’ relatives, general practitioners and local hospitals, as well as through data collection from our institutional quality information management system and electronic documentation system. In cases when patients or patients’ next of kin could not be contacted, the cut-off of the study for those particular patients was set as the date of the last documented follow-up contact. Generally, no patients were lost from follow up.

Surgical procedure

Aortic dissection definition was made in accordance with current international guidelines.¹³ Before surgery a computed tomography (CT) scan was performed and analysed. Surgery extent was planned depending on the location of the aortic entry tear in the CT scan. Further, extent of aortic repair was re-evaluated during surgery due to a better intra-operative visualization of the aortic entry tear site for Stanford type A dissection. Surgery extent depended on location of the aortic entry tear. If the aortic entry tear was located after the aortic valve and before branch-off of the brachiocephalic trunk, ascending aortic repair was performed in our institution. If the aortic entry tear was located in the lesser curvature, aortic hemiarch replacement was conducted. If the aortic entry tear involved the whole aortic arch including supra-aortic vessels the whole aortic arch was replaced with reinsertion of the vessels. In our institution we tried to perform an invasive surgical procedure depending on the location of the aortic entry tear site not on featuring the more radical arch replacement surgery for reducing the rate of false lumen patency on long-term view.

In our institution current practice was accordingly the aforesaid scheme with comparison of three different aortic entry tear sites and their appropriate aortic tear focused, minimalistic and conservative surgical repair. Surgical approaches for Stanford A AAD used in our centre have been described in detail elsewhere.^14,15 In brief, access to the surgical field was ensured through a median sternotomy whereas cannulation was performed either prior to sternotomy through the right axillary artery with a single purse-string suture with 5-0 prolene and an 18–20 French arterial cannula (Fem-Flex II; Edwards Lifesciences, Irvine, CA, USA), through the femoral artery after surgical cut down using 5-0 prolene and an 18–20 French arterial cannula, or directly through the aortic arch after opening the chest with a double purse-string suture with 4-0 prolene for direct aortic cannulation. A bolus of unfractionated heparin of 300–400 IU per kg body weight was administered prior to cannulation and establishment of a cardiopulmonary bypass (CPB) to achieve an activated clotting time of more than 400 s. After initiation of systemic cooling on the CPB a left ventricle vent catheter was usually placed through the right superior pulmonary vein. The aortic cross-clamp was applied to the proximal aspect of the aortic arch; alternatively the ascending aorta was incised and opened in circulatory arrest. Venous cannulation was performed through the right atrium using a 34–39 French double-stage cannula (Maquet, Rastatt, Germany). In cases of direct aortic or femoral cannulation a short period of hypothermic circulatory arrest (HCA) was initiated for inspection of the aortic arch followed by an extended period of selective cerebral perfusion and moderate hypothermia for distal anastomosis. In cases of axillary cannulation a short period of HCA was avoided as cerebral perfusion was ensured through the right carotid artery after clamping the brachiocephalic trunk. For repair of the aortic root, supracoronary aortic replacement, composite replacement or an aortic valve-sparing technique was performed according to the extent of the dissection and intra-operative findings of the aortic valve. In cases of central cannulation after completing the distal anastomosis the arterial cannula was inserted into the prosthesis, the prosthesis was clamped, CPB was restarted, and the patient rewarmed. While rewarming, the repair of the aortic root was completed, the anastomosis between the proximal and distal prosthesis was performed, and the aortic clamp was removed after a careful de-airing procedure. A meticulous haemostasis was performed before closing the chest whereas transfusion requirements were guided using thromboelastography available in our unit.

Statistical analysis

IBM SPSS Statistics for Windows, Version 25 (Released 2017. IBM Corp., Armonk, NY, USA) was used for statistical analysis. All data were presented as continuous or categorical variables. Continuous data were checked for normality using one sample Kolmogorov–Smirnov test and histograms. All continuous variables were expressed as means ± standard deviation for normally distributed variables or medians (interquartile ranges) for non-normally distributed continuous variables. Categorical data were expressed as total numbers and percentages. Statistical comparisons of continuous variables were performed using unpaired analysis of variance for normally distributed and nonparametric Kruskal–Wallis test for non-normally distributed variables, whereas categorical variables were assessed using Pearson’s chi-square test or Fisher’s exact test depending on the minimal expected count in each crosstab. A multinomial logistic regression analysis was performed for subgroup analysis comparing odds ratios (OR) of arch surgery to hemiarch and ascending aorta surgery, respectively. Kaplan–Meier survival analysis was performed for overall survival estimation and estimation of survival free from major cerebrovascular events over long-term follow up comparing the impact of ascending aorta, hemiarch and arch surgery, whereas logrank (Mantel–Cox) and Breslow (generalized Wilcoxon) tests were applied for calculation of significances for earlier and later follow-up phases.

Results

Univariate analysis

The proportion of patients in the ascending aorta replacement group (n = 126, 52.5%) was higher than that of the hemiarch (n = 72, 30.0%) and total arch replacement group (n = 42, 17.5%). Univariate analysis comparing all three surgical approaches in terms of demographics and preoperative baseline characteristics showed in most cases no statistically significant differences regarding demographic and clinical parameters that were statistically similar among the three groups analysed (Table 1). Intra-operative use of direct and peripheral cannulation strategies, cardioplegia, proportions of Bentall or David procedures as well as additional coronary artery bypass grafting were similarly distributed among the groups (p > 0.05).

Table 1.

Association of demographics and preoperative baseline characteristics with ascending aorta, hemiarch and arch replacement groups.

	Ascending aorta(n = 126)	Hemiarch (n = 72)	Arch(n = 42)	p value
Age (years)	62 (49;73)	67 (49;75)	60 (54;73)	0.140
Height (cm)	174 (165;180)	175 (169;180)	176 (170;180)	0.190
Weight (kg)	80 ± 16.0	82 ± 16.9	78 ± 15.7	0.426
Gender (male)	77 (61.1%)	49 (68.1%)	27 (64.3%)	0.618
LVEF (%)	60 (50;60)	60 (55;60)	60 (54;60)	0.726
Euroscore	12 (9;14)	11 (8;13)	11 (9;14)	0.254
Log. Euroscore	30 (16;48)	25 (13;42)	30 (17;49)	0.192
Iatrogenic origin	8 (9.1%)	6 (13.6%)	2 (6.5%)	0.556
Reduced perfusion	40 (31.7%)	16 (22.2%)	14 (33.3%)	0.295
Pericardial effusion	57 (45.2%)	37 (51.4%)	14 (33.3%)	0.174
Coronary dissection	16 (12.7%)	7 (9.7%)	2 (4.8%)	0.336
Neurology normal	84 (67.2%)	55 (76.4%)	29 (69.0%)	0.390
Neurology weak	14 (11.2%)	10 (13.9%)	2 (4.8%)	0.316
Neurology coma	27 (21.6%)	7 (9.7%)	11 (26.2%)	0.049
Comorbidities
Arterial hypertension	89 (70.6%)	61 (84.7)	31 (73.8%)	0.083
Diabetes mellitus	11 (8.7%)	6 (8.3%)	1 (2.4%)	0.380
Elevated creatinine^*	41 (32.5%)	21 (29.2%)	13 (31.0%)	0.885
PVD	10 (7.9%)	3 (4.2%)	2 (4.8)	0.521
CAD	21 (16.7%)	16 (22.2%)	8 (19.0%)	0.628
AV pathology	61 (48.4%)	26 (36.1)	11 (26.2)	0.025
Connective tissue disorder^$	3 (3.9%)	0 (0%)	1 (3.3%)	0.172
Blood and coagulation parameters
Haemoglobin (g/L)	129 ±15,6	130 ±17.8	121 ±22.6	0.041
Platelets preoperatively (U)	201 (149;251)	172 (139;229)	177 (125;233)	0.666
Fibrinogen preoperatively (g/L)	3.1 (2.5;3.8)	2.7 (2.0;3.4)	3.3 (2.5;5.1)	0.331
Thrombocytes × 10⁹/L
aPTT preoperatively	29 (26;35)	29 (26;33)	30 (26;35)	0.802
Quick	80 (64;96)	87 (64;98)	83 (53;95)	0.909
Location of primary entry tear
Aorta ascendens	116 (92.1%)	40 (55.6%)	22 (52.4%)	< 0.001
Proximal aortic arch	9 (7.1%)	23 (31.9%)	14 (34.1%)	< 0.001
Distal aortic arch	1 (0.8%)	3 (4.2%)	15 (36.6%)	< 0.001
Aorta descendens	3 (2.4%)	6 (8.3%)	2 (4.9%)	0.157
Extension of dissection
Aorta ascendens	26 (21.1%)	11 (15.5%)	5 (11.9%)	0.334
Aorta thoracalis descendens	35 (28.5%)	21 (29.6%)	9 (21.4%)	0.611
Aorta abdominalis	9 (7.3%)	7 (9.9%)	4 (9.5%)	0.799
Aorta iliaca	54 (43.9%)	32 (45.1%)	25 (59.5%)	0.199

Serum creatinine > 97.26 µmol/L. ^$Connective tissue disorders summarize Marfan, Ehlers–Danlos and Loeys–Dietz syndromes. Percentages are calculated as the number of events on total number of patients with available data for the variable under examination for each subgroup. aPTT, activated partial thromboplastin time; AV, aortic valve; CAD, coronary artery disease; LVEF, left ventricular ejection fraction; PVD, peripherial vascular disease.

In terms of intra-operative variables and intra- and early postoperative variables significant differences in the arch replacement group in comparison to the ascending aorta and hemiarch replacement groups were found, particularly higher cross-clamp time, longer duration of surgery, longer CPB time, longer selective brain perfusion time, longer reperfusion time, longer mechanical ventilation, higher drainage output over 24 h, higher incidence of ischaemic or haemorrhagic stroke during the hospital stay, higher intra-operative mortality (and in-hospital mortality) (all p < 0.05). Corresponding to higher in-hospital mortality the arch replacement surgery group was associated with a trend towards higher 30-day mortality (p = 0.078). Moreover, total arch repair group was associated with a significantly higher intra-operative transfusion requirement for RBC (p = 0.016) as well as postoperative RBC transfusions (p = 0.047). Also, a higher postoperative transfusion requirement of FFP (p = 0.023) together with a significantly higher need for reopening for bleeding (p = 0.031) was noted. However, the incidence of bleeding without the need for surgical revision did not show significant differences among the three groups (p = 0.126).

Incidences of postoperative myocardial infarction (p = 0.654) and renal failure requiring renal haemofiltration (p = 0.414) were similarly distributed among the three groups (Tables 2 and 3).

Table 2.

Association of operative strategy with ascending aorta, hemiarch and arch replacement groups.

	Ascending aorta (n = 126)	Hemiarch(n = 72)	Arch(n = 42)	p value
Surgical strategy
Bentall procedure	43 (34.1%)	22 (30.6%)	7 (16.7%)	0.101
David procedure	6 (4.8%)	1 (1.4%)	1 (2.4%)	0.415
Aorta descendens replacement	2 (1.6%)	0 (0.0%)	15 (35.7%)	< 0.001
CABG	23 (18.3%)	11 (15.3%)	3 (7.1%)	0.225
Redo procedure	11 (8.7%)	2 (2.8%)	5 (11.9%)	0.152
SBP	78 (61.9%)	70 (98.6%)	42 (100.0%)	< 0.001
SBP bilateral	55 (44.0%)	48 (67.6%)	32 (80.0%)	< 0.001
Cannulation
Aorta axillaris	103 (81.7 %)	60 (83.3%)	31 (73.8%)	0.428
Aorta ascendens/ proximal arch	20 (15.9%)	11 (15.3%)	10 (24.4%)	0.400
Aorta femoralis	3 (2.4%)	2 (2.8%)	0 (0.0%)	0.572
Cardioplegia
Buckberg	111 (88.1%)	63 (87.5%)	39 (95.1%)	0.396
Calafiore	10 (7.9%)	8 (11.1%)	2 (4.9%)	0.499
Bretschneider	5 (4.0%)	2 (2.8%)	0 (0.0%)	0.423

Percentages are calculated as the number of events on total number of patients with available data for the variable under examination for each subgroup. CABG, coronary artery bypass grafting; SBP, selective brain perfusion.

Table 3.

Association of intra- and early postoperative variables with ascending aorta, hemiarch and arch replacement groups.

	Ascending aorta (n = 126)	Hemiarch(n = 72)	Arch(n = 42)	p value
Cross-clamp time (min)	77 (61;97)	95 (59;126)	133 (108;169)	< 0.001
Duration of surgery (min)	297 (236;405)	340 (256;409)	385 (298;493)	0.001
Cardiopulmonary bypass time (min)	155 (120;207)	183 (135;224)	234 (198;314)	< 0.001
SBP (min)	19 (12;27)	26 (17;47)	60 (52;80)	< 0.001
SBP flow (ml/min)	900 (800;900)	900 (900;900)	900 (850;900)	0.464
Reperfusion time (min)	61 (38;82)	71 (56;87)	85 (60;108)	0.002
RBC intra-operatively (U)	6 (4;9)	6 (4;8)	8 (5;14)	0.016
FFP intra-operatively (U)	6 (4;9)	6 (4;8)	8 (6;11)	0.095
Platelets intra-operatively (U)	2 (1;2)	2 (1;3)	2 (1;3)	0.242
RBC postoperatively (U)	4 (1;10)	7 (2;11)	7 (4;17)	0.047
FFP postoperatively (U)	2 (1;6)	4 (1;8)	7 (1;13)	0.023
ICU stay (days)	5 (3;12)	5 (3;12)	12 (4;19)	0.057
Time for intubation (days)	2 (1;7)	2(1;6)	5 (2;15)	0.032
Drainage output over 24 h (ml)	890 (554;1938)	1080 (700;2025)	1620 (1000;3000)	0.009
Temporary neurological disorder	41 (34.2%)	27 (38.0%)	13 (34.2%)	0.853
Stroke	17 (13.8%)	9 (12.7%)	12 (30.0%)	0.034
Myocardial infarction	31 (25.0%)	22 (30.6%)	12 (30.0%)	0.654
Gastrointestinal complications	17 (13.7%)	10 (13.9%)	1 (2.5%)	0.133
Renal CVVH	23 (18.5%)	14 (19.4%)	11 (28.2%)	0.414
Respiratory TT virus	34 (27.4%)	22 (30.6%)	17 (42.5%)	0.199
Tachyarrhythmia absoluta	42 (43.1%)	27 (38.0%)	19 (47.5%)	0.316
Infection	62 (50.0%)	29 (40.3%)	22 (55.0%)	0.259
Rethorax	24 (19.5%)	17 (23.6%)	16 (40.0%)	0.031
Bleeding	54 (43.5%)	39 (54.2%)	24 (60.0%)	0.126
In-hospital stay (days)	13 (7;20)	12 (6;20)	5 (5;22)	0.728
Intra-operative mortality	4 (3.2%)	2 (2.8%)	5 (11.9)	0.045
ICU mortality	13 (10.4%)	13 (18.1%)	7 (17.1%)	0.263
In-hospital mortality	15 (12.2%)	16 (23.5%)	12 (30.8%)	0.017
30-day mortality	17 (13.6%)	15 (20.8%)	12 (28.6%)	0.078

Percentages are calculated as the number of events on total number of patients with available data for the variable under examination for each subgroup. CVVH, continuous veno-venous haemofiltration; FFP, fresh frozen plasma; ICU, intensive care unit; RBC, red blood cells, SBP, selective brain perfusion.

Multinomial logistic regression analysis

Multinomial logistic regression was applied for early outcomes such as stroke, bleeding, need for reopening, myocardial infarction, duration of intensive care unit (ICU) stay, and in-hospital and 30-day mortality, whereas increased odds could be found for most variables in the arch replacement group in comparison to the ascending aorta and hemiarch repair groups. The subgroup analysis revealed statistical significance for stroke (OR 2.67, p = 0.023), reopening for bleeding (OR 2.75, p = 0.010), ICU mortality (OR 2.54, p = 0.010) and in-hospital mortality (OR 2.20, p = 0.009) for arch surgery in comparison to ascending aorta surgery. Notably, OR did not reach statistical relevance in terms of myocardial infarction (OR 1.29, p = 0.532). In correlation with the significantly higher odds for reopening for bleeding a corresponding trend was found for bleeding without the need for surgical revision (OR 1.95, p = 0.072) for the arch replacement group compared with the ascending aorta repair group (Table 4).

Table 4.

Odds ratios, 95% confidence interval and p values of stroke, bleeding, reopening for bleeding, myocardial infarction and in-hospital and 30-day mortality for the arch surgery group in comparison to the ascending aorta surgery group in Stanford A acute aortic dissection.

	Odds ratio	95% confidence interval	p value
Stroke	2.67	1.14–6.24	0.023
Bleeding	1.95	0.94–4.02	0.072
Reopening	2.75	1.27–5.95	0.010
Myocardial infarction	1.29	0.58–2.83	0.532
In-hospital mortality	2.20	1.34–7.63	0.009
Intensive care unit mortality	2.54	1.09–5.92	0.030

In terms of arch surgery in comparison to hemiarch surgery, a subgroup analysis revealed a significantly higher OR for stroke (OR 2.95, p = 0.029) and a trend towards higher incidence for reopening for bleeding (OR 2.16, p = 0.071) and intra-operative mortality (OR 4.74, p = 0.071). ORs were statistically similar in terms of bleeding without the need for surgical revision (OR 1.27, p = 0.551), myocardial infarction (OR 0.97, p = 0.532), in-hospital mortality (OR 1.45, p = 0.413) and 30-day mortality (OR 1.52, p = 0.350) for the arch replacement versus hemiarch repair group (Table 5).

Table 5.

Odds ratios, 95% confidence interval and p values of stroke, bleeding, reopening for bleeding, myocardial infarction and intra-operative-, in-hospital and 30-day mortality for the arch surgery group in comparison to the hemiarch surgery group in Stanford A acute aortic dissection.

	Odds ratio	95% confidence interval	p value
Stroke	2.95	1.04–7.81	0.029
Bleeding	1.27	0.58–2.78	0.551
Reopening	2.16	0.94–4.98	0.071
Myocardial infarction	0.97	0.42–2.26	0.951
Intra-operative mortality	4.74	0.87–25.64	0.071
In-hospital mortality	1.45	0.60–3.48	0.413
30-day mortality	1.52	0.63–3.66	0.350

Long-term outcomes

In order to analyse the impact of the three surgical strategies on long-term outcomes after surgery for Stanford A AAD, a Kaplan–Meier survival-estimation analysis and plot with up to 9 years of follow up was performed. In this analysis long-term overall survival and long-term survival free from major cerebrovascular events showed similar results for all three groups using the logrank (Mantel–Cox) test (p = 0.166 and p = 0.062, respectively). However, both outcomes showed a statistical trend towards poorer overall survival and poorer survival free from cerebrovascular events for the arch surgery group compared with the ascending aorta and hemiarch surgery group in the Breslow (generalized Wilcoxon) test (p = 0.079 and p = 0.059, respectively), which is more sensitive to earlier follow-up periods in the Kaplan–Meier estimation (Figures 1 and 2 and Table 6).

Figure 1.

Kaplan–Meier estimation with long-term overall cumulative survival up to 9 years of follow up of the ascending aorta, hemiarch and arch replacement groups. Patients were censored at the cut-off of the study.

Figure 2.

Kaplan–Meier estimation with survival free from major cerebrovascular events (ischaemic or haemorrhagic stroke) up to 9 years of follow up of the ascending aorta, hemiarch and arch replacement groups. Patients were censored at the cut-off of the study.

Table 6.

Kaplan–Meier survival estimation analysis. Patients at risk.

		30 d	6 m	1a	2a	3a	4a	5a	6a	7a	8a	9a
Ascending aortic repair	a	107	97	84	62	44	40	26	20	12	4	0
	b	100	90	78	55	37	32	21	17	11	5	0
Hemiarch aortic repair	a	56	46	41	35	30	25	21	15	9	4	0
	b	54	43	38	32	28	23	19	13	9	4	0
Aortic arch repair	a	26	19	17	13	11	7	5	3	2	1	0
	b	32	15	13	10	7	4	3	2	1	0

a, overall cumulative survival; b, overall cumulative survival free from major cerebrovascular events.

There were significant differences in terms of in-hospital mortality among the three surgical approaches for the ascending aorta, hemiarch and arch groups (12.2% versus 23.5% versus 30.8%, p = 0.017), and a trend in terms of 30-day mortality (13.6% versus 20.8% versus 28.6%, p = 0.078). Long-term overall cumulative survival analysis accounted for 82.5% versus 72.2% versus 66.7% at 1 year, 77.0% versus 69.4% versus 64.3% at 3 years, and 76.2% versus 68.1% versus 64.3% at 5 years after surgery (Figure 1). Kaplan–Meier estimation for long-term survival free from major cerebrovascular events with up to 9 years of follow up showed in 89.7% versus 91.7% versus 81.0% at 1 year, 88.1% versus 90.3% versus 78.6% at 3 years, and 87.3% versus 90.3% versus 76.6% at 5 years after surgery (Figure 2).

Discussion

AAD is a complex cardiovascular life-threatening disease that is associated with high perioperative morbidity and mortality up to 10–25% in spite of advances in techniques and perioperative management in the last decades.^14–20 AAD affects approximately 3.5 per 100,000 persons per year.²¹ Therefore, early recognition and surgical correction is recommended to prevent devastating complications such as aortic rupture. However less attention was payed to investigating different surgical approaches in terms of invasiveness while addressing Stanford A AAD.

The literature reveals that the best effective surgical approach is still being debated.¹⁶ The aim of this study was to compare outcomes of three different surgical approaches in patients with Stanford A AAD from a high-volume centre. In addition to previous reports on AAD our group used a multinomial logistic regression analysis for subgroup analysis. In our study group there were no significant differences in most cases in terms of demographics and preoperative baseline characteristics leading to a similar distribution of important preoperative predictors among the three groups.

Some of the most devastating perioperative complications of AAD potentially associated with significant impairment of quality of life of patients are temporary neurological disorders and major cerebrovascular events. Permanent strokes especially do not only affect a patient’s condition but also the whole patient’s social environment aside from causing additional financial burden. In our study we did not find any differences in terms of early temporary neurological disorders among patients that underwent replacement of the ascending aorta, hemiarch and arch. We also found that arch replacement versus replacement of the hemiarch or ascending aorta showed significantly poorer in-hospital stroke rates. This might be associated with higher invasiveness of the arch procedure and corroborates the findings by Kim and colleagues who also showed elevated cerebrovascular complications after total arch replacement.²² However, Trivedi and colleagues found that stroke rates in patients undergoing arch replacement significantly decrease when total arch replacement is combined with additional complete carotid replacement, though only a relatively small patient cohort was analysed in their study.²³ This may be a potential solution for decreasing the risk of neurological complications for isolated cases when total aortic arch replacement is unavoidable. Further, Goebel and colleagues reported on minimally invasive aortic surgery via partial upper sternotomy with no major cerebrovascular events.²⁴ However this evidence should be confirmed by further investigations due to the relatively small patient cohort analysed. The importance of stroke was also highlighted by Liu and colleagues who found that stroke was an independent predictor for adverse outcome.²⁵ Nevertheless, there is still a lack of data on the impact of different surgical approaches on long-term neurological outcomes in patients undergoing aortic repair for Stanford A AAD.⁹ Our study provided first long-term results on freedom from major cerebrovascular events that were significantly poorer in the total arch group in accordance with a higher incidence of in-hospital stroke in this more invasive group.

The all-cause mortality in our study differed significantly among the three groups increasing with the invasiveness of the procedure corroborating the findings published by Kim and colleagues who found that total arch repair was associated with higher morbidity and mortality compared with less invasive approaches.²² Nevertheless, residual false lumen still represents a well-known risk factor for further complications whereas complete resection of all entry tears is required for ensuring a complete thrombosis of the false lumen. Therefore, less aggressive surgery may potentially fail to achieve this objective. In an effort to maximize resection of entry tears and to decrease the incidence of residual false lumen, several groups reported on the routine replacement of the total arch with outcomes including mortality rates ranging from 10% to 20%.^26–29 Song and colleagues showed that ascending aorta or hemiarch replacement compared with total arch replacement resulted in a significantly higher incidence of partial thrombosis of the residual false lumen in the descending thoracic aorta being a significant independent predictor for aortic enlargement, the need for reopening for bleeding and poorer long-term survival. Consequently, patients who underwent total arch replacement showed a more favourable outcome than those who underwent ascending aorta or hemiarch replacement.³⁰ In contrast, our findings revealed a higher incidence of reopening for bleeding and poorer in-hospital and long-term survival in patients undergoing arch replacement in comparison to patients with ascending aorta and hemiarch repair.

Several groups also reported on an even more aggressive approach involving total arch replacement and applying a stented elephant trunk in the proximal descending thoracic aorta for Stanford A AAD.^31,32 However, most studies providing support for more aggressive surgical approaches in the AAD setting either lack control groups or adequate adjustment for baseline risk profiles between study and control groups.^26-29,31,32 Moreover, Ghazy and colleagues focused on quality of life after aortic surgery and found that adopting a more aggressive surgical strategy does not necessarily improve quality of life compared with less invasive approaches.³³ This supports our findings for a more restrictive surgical approach.

Latest studies published by Colli and colleagues in 2018 and 2016^34,35 and by Russo and colleagues³⁷ revealed that despite substantial progress in surgical techniques and perioperative management, the best surgical approach for patients suffering from Stanford A dissection is still controversial and outcomes highly dependent on perioperative risk factors.

In 2018 Colli and colleagues performed surgical approaches on patients with Stanford A AAD without intimal tear in the aortic arch and found that patients with total aortic arch repair suffered from a higher 30-day mortality.³⁴ However long-term mortality in the total aortic arch repair group was similar to the ascending and hemiarch repair groups. These results corroborate our results focusing on less invasive or aggressive surgical procedures. Colli and colleagues pointed out in the absence of a visualized intimal tear in the aortic arch a more radical arch replacement surgery for reducing the rate of false lumen patency on long-term view. Future studies featuring comparison of surgical approaches under consideration of perioperative risk factors in terms of early and long-term outcomes could provide further evidence. In addition to our findings Colli and colleagues stated that the incidence of postoperative complications of patients with Stanford A AAD was related to older age and longer cross-clamp time.³⁵

In their 33-year follow up Russo and colleagues focused on early and especially long-term outcomes of patients suffering from Stanford A AAD comparable to our results for a 9-year follow up.³⁶ In addition, he found severe aortic regurgitation at the time of surgery to be a significant risk factor for reintervention during follow up suggesting the need for a thorough debate on surgical options and assessment. However in our study we focused on comparison of three different surgical approaches of Stanford A AAD repair in terms of outcomes using minimalistic, conservative and a more aortic entry tear-focused strategy.

Corroborating our results, Cabasa and Pochettino stated significantly longer cross-clamp time in more invasive aortic replacement surgery.¹⁶ In our study, longer duration of surgery with significantly extended cross-clamp and CPB time due to the more invasive nature of total aortic arch replacement resulted in a significantly higher incidence of bleeding and transfusion requirements. Also, there was a trend towards a higher incidence of reopening for bleeding in the total arch group compared with the hemiarch group in the subgroup analysis. Interestingly, minimally invasive procedures via partial upper sternotomy might decrease bleeding complications as reported by centres with expertise in this approach.²⁴ Also, consistent with our results, Liu and colleagues stated that prolonged cross-clamp time and administration of RBC may lead to adverse outcome.²⁶ Furthermore, duration of ventilation time differed significantly among the three groups in favour of less invasive approaches with a trend toward longer ICU stay in the total arch replacement group. Interestingly, there were no significant differences in terms of other postoperative adverse events, such as gastrointestinal complications, infections, renal failure and myocardial infarction, among the three groups.

Due to still controversial results in terms of the extent of surgery in patients undergoing aortic repair for Stanford A AAD the surgical approach should always be adapted to patients’ individual circumstances.²⁶ Each case should be evaluated accurately in order to achieve an acceptable outcome.³⁷ It should also be taken into consideration that a new dissection process may arise when more aggressive surgery is not applied in appropriate cases, whereas every redo procedure represents an additional trauma often followed by severe complications and higher mortality.³⁸ Newer techniques including frozen elephant trunk prostheses promise good long-term results. Nevertheless, these new techniques require further investigations.³⁹

Limitations of the study

This study is a retrospective analysis of prospectively collected registry data from a single centre. The study power was limited due a relatively small patient cohort. The nonrandomized design as well as the complexity and variability of the pathophysiology and morphology of Stanford A AAD may also have affected the results. This study represents the experience of a single large tertiary referral centre and might not be generalized to other centres.

Conclusion

In summary, the present analysis based on our experience with surgical repair of Stanford A AAD revealed that with total aortic arch replacement, the incidence of perioperative complications and in-hospital mortality increased significantly in comparison with ascending aortic and hemiarch repair surgery. In-hospital and long-term stroke rates and the incidence of reopening for bleeding also scaled up from ascending aorta over hemiarch to arch group.

Footnotes

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflict of interest statement

The authors declare no conflicts of interest in preparing this article.

ORCID iDs

Julia Merkle

Georg Schlachtenberger

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