Acute Uncomplicated Type B Aortic Dissection Research Articles

Acute Type B Aortic Dissection: Insights From a Single-Center Retrospective Experience Over 12 Years.

The treatment of acute type B aortic dissection (ATBAD) is currently a challenge for vascular surgeons, because of the early morbidity and mortality rates and the high risk of late aortic events up to 50% at 5 years. This study presents the initial outcomes of ATBAD treatment using optimal medical therapy alone or combined with proximal entry tear stent-graft coverage. Additionally, it provides an analysis of the evolution of the aortic diameter and its clinical consequences during the chronic phase in each group. Conducted as a retrospective, single-center study, we enrolled all consecutive ATBAD patients (n=130) treated between 2008 and 2020. The primary analysis studies the entire patient cohort based on their initial management approach, namely, medical treatment alone for uncomplicated ATBAD (n=67) or combined with stent-graft entry tear coverage (n=63). We also conducted a subgroup analysis to investigate factors associated with disease progression in the medical management group. Median follow-up was 29.5 months. During this time aneurysmal evolution was observed in: 42.4% of cases in the medical group compared with 21.8% in the stent-graft group, primarily affecting the thoracic aorta. The stent-graft group exhibited significant aortic remodeling, with a decrease in false lumen (FL) and thoracic aortic diameters. Initial aortic diameter ≥40 mm and FL ≥22 mm were independent risk factors for aneurysmal degeneration. Five-year survival was consistent at 76.1% in both groups. This study confirms the safety and efficacy of stent-graft entry tear coverage for ATBAD. Initial thoracic endovascular aortic repair (TEVAR) appears to reduce late aortic events by promoting aortic remodeling. Considering TEVAR's safety and potential to prevent late aortic complications, it may be considered for uncomplicated ATBAD patients with an initial aortic diameter ≥40 mm or an FL ≥22 mm. This study validates the efficacy and safety of using endovascular stent grafts to seal the proximal entry tear in cases of acute type B aortic dissections, compared to optimal medical therapy. Aortic remodelling significantly benefits from endovascular stent graft coverage of the proximal entry tear. Given the heightened risk of late aortic events observed in the medical therapy cohort, there appears to be a necessity for including endovascular interventions in the management of uncomplicated acute type B aortic dissections, particularly when aortic diameter is ≥40 mm and false lumen diameter is ≥22 mm.

Systemic immune-inflammation index predicts the clinical outcomes in patients with acute uncomplicated type-B aortic dissection undergoing optimal medical therapy

BackgroundOptimal medical therapy (OMT) for uncomplicated type B aortic dissection (uTBAD) provides excellent short-term outcomes during follow up; however, its long-term therapeutic effectiveness is unsatisfactory. This study evaluated the predictive value of systemic immune-inflammation index (SII) for adverse events among patients with acute uTBAD undergoing OMT.MethodsWe performed a retrospective analysis of a prospectively maintained database between 2013 and 2020. The primary end point in this study was composite outcomes including aortic intervention, all-cause mortality, retrograde type A aortic dissection (rTAAD) and aortic diameter growth > 5 mm. The patients were divided into high and low SII groups according to the optimal cut-off value of SII as determined using the receiver operating characteristic curve. Cox proportional hazards models were constructed to estimate the hazards ratios and identify the predictors of composite outcomes.ResultsA total of 124 patients with acute uTBAD who underwent OMT were enrolled. One patient died during hospitalisation. At the end of a mean follow-up duration of 51 ± 23 months, 53 (43.1%) patients experienced composite outcomes, 15 patients (12.2%) died, 31 (25.2%) underwent aortic intervention, 21 (17.1%) exhibited diameter growth of > 5 mm, and 2 developed rTAAD. The patients were divided into low SII group (n = 78, 62.9%) and high SII group (n = 46, 37.1%) as per the optimal cut-off SII value of 1449. The incidence of composite outcomes in high SII group was significantly higher than that in low SII (28 [60.9%] vs. 26[33.3%], p < 0.01). Patients with high SII demonstrated significantly higher mortality rate than those with a low SII (11 [23.9%] vs. 5 [6.4%], respectively; p < 0.01). In addition, the high SII group had significantly higher rate of aortic-related reinterventions than the low SII group (16 [34.8%] vs. 15 [19.2%], p = 0.03). Multivariable Cox analyses showed that a high SII score was independently associated with composite outcomes rate (hazard ratio, 2.15; 95% confidence interval, 1.22–3.78; p < 0.01).ConclusionsThe long-term therapeutic effectiveness of OMT alone in patients with acute uTBAD is unsatisfactory. An SII > 1449 at the time of diagnosis is an independent predictor of OMT failure.

Management of acute type B aortic dissection: treatment and follow-up

Aortic dissection is a life-threatening condition caused by a tear in the tunica intima which creates a false lumen into the aortic wall. Acute type B aortic dissection (TBAD) is defined by the presence of the entry tear in the aorta distal to the left subclavian artery, without ascending aorta and arch involvement, and accounts for 25-40% of all aortic dissections. Optimal medical therapy (OMT), focused on blood pressure and heart rate control, remains the gold standard treatment, especially for patients with uncomplicated TBAD, while complicated dissections require surgical therapy. Recent studies have shown that a considerable number of patients treated only with OMT develop late aorta-related complications that increase morbidity and mortality, as well as the need for surgical intervention. During the last decades, emerging evidence indicates that thoracic endovascular aortic repair (TEVAR) is safe and effective in the treatment of TBAD, both complicated and uncomplicated, with improved long-term survival outcomes and aortic remodeling in combination with OMT compared to OMT alone. However, in cases of acute uncomplicated TBAD the optimal timing for TEVAR is not entirely clarified and there is lack of long-term evidence. Therefore, the role of pre-emptive TEVAR for these patients is still uncertain and the management of acute uncomplicated TBAD remains challenging.

Postoperative acute kidney injury after thoracic endovascular aortic repair for acute type B aortic dissection

BackgroundThoracic endovascular aortic repair (TEVAR) has evolved as the standard for treating complicated acute type B aortic dissection (ATBAD). Acute kidney injury (AKI) is a common complication in critically ill patients and is commonly observed in patients with ATBAD. The purpose of the study was to characterize AKI after TEVAR. MethodsAll patients who underwent TEVAR for ATBAD from 2011 through 2021 were identified using the International Registry of Acute Aortic Dissection. The primary end point was AKI. A generalized linear model analysis was performed to identify a factor associated with postoperative AKI. ResultsA total of 630 patients presented with ATBAD and underwent TEVAR. The indication for TEVAR was complicated ATBAD in 64.3%, high-risk uncomplicated ATBAD in 27.6%, and uncomplicated ATBAD in 8.1%. Of 630 patients, 102 (16.2%) developed postoperative AKI (AKI group) and 528 patients (83.8%) did not (non-AKI group). The most common indication for TEVAR was malperfusion (37.5%). In-hospital mortality was significantly higher in the AKI group (18.6% vs 4%; P < .001). Postoperatively, cerebrovascular accident, spinal cord ischemia, limb ischemia, and prolonged ventilation were more commonly observed in the AKI group. The expected mortality was similar at 2 years between the two groups (P = .51). Overall, the preoperative AKI was observed in 95 (15.7%) in the entire cohort consisting of 60 (64.5%) in the AKI group and 35 (6.8%) in the non-AKI group. A history of CKD (odds ratio, 4.6; 95% confidence interval, 1.5-14.1; P = .01) and preoperative AKI (odds ratio, 24.1; 95% confidence interval, 10.6-55.0; P < .001) were independently associated with postoperative AKI. ConclusionsThe incidence of postoperative AKI was 16.2% in patients undergoing TEVAR for ATBAD. Patients with postoperative AKI had a higher rate of in-hospital morbidities and mortality than those without. A history of CKD and preoperative AKI were independently associated with postoperative AKI.

Readmission after early thoracic endovascular aortic repair versus medical management of acute type B aortic dissection

BackgroundThe use of thoracic endovascular aortic repair (TEVAR) for the management of acute uncomplicated type B aortic dissection (TBAD) has increased. Although the results from early studies were promising, larger randomized trials evaluating TEVAR are lacking. It is also unclear where sufficient equipoise exists for such trials. In the present study, we evaluated the number of readmissions and unplanned operations after TEVAR vs those after medical management as the initial treatment of acute uncomplicated TBAD and the frequency of each treatment in this population. MethodsWe performed a multi-institutional retrospective review of patients with acute TBAD from 2015 to 2020 with the 1-year outcomes available, excluding patients with prior aortic intervention or chronic, iatrogenic or traumatic etiologies. The primary exposure was TEVAR vs medical management at the index admission. The patient demographics, clinical presentation, and imaging findings were analyzed using bivariate and multivariate logistic regression for the primary outcomes of unplanned readmission and/or operation after the initial admission. The secondary outcomes were mortality, myocardial infarction, stroke, renal failure requiring dialysis, retrograde type A dissection, and length of stay. We hypothesized that the readmissions would be higher with medical management. ResultsA total of 216 patients with TBAD (47 with complicated and 169 with uncomplicated) from two large academic centers were identified. Of the 169 patients with uncomplicated TBAD, 83 (49%) had been treated medically and 86 (51%) had undergone TEVAR at the initial admission. No differences were found in the demographics or high-risk imaging features at presentation. The medically managed patients had had higher rates of unplanned readmission (34% vs 9%; P = .0001) and operation (28% vs 8%; P = .0007) but shorter lengths of stay (6.3 vs 13.1 days; P < .0001). No differences were found in mortality, although the rate of myocardial infarction was higher in the medically managed group (10.8% vs 2.3%; P = .02). Although 28% of the medically managed patients had later required operation, they had had morbidity and mortality similar to those of patients who had undergone initial TEVAR. Initial medical management was associated with unplanned readmission (odds ratio, 8.3; P = .02) and the need for operation (odds ratio, 4.56; P = .006). No differences were found in the outcomes according to the involved aortic zones. ConclusionsIn the present study, medical management of acute uncomplicated TBAD was associated with higher rates of readmission and the need for unplanned operation compared with TEVAR. However, no differences were found in the 1-year mortality for the patients for whom medical management had failed. Because one half of the patients had undergone medical management and one half had undergone early TEVAR, this finding suggests clinical equipoise for the treatment of acute uncomplicated TBAD. Therefore, a larger randomized trial appears warranted to determine whether a clear benefit exists for early TEVAR.

Endovascular repair versus best medical treatment for uncomplicated acute type B acute aorta dissection: a meta-analysis.

In acute type B aortic dissection (TBAD) patients, thoracic endovascular aorta repair (TEVAR) and best medical treatment (BMT) have both been employed for the clinical management of this condition. The relative efficacy of TEVAR and BMT when used to manage cases of acute uncomplicated TBAD, however, remains to be clarified. To conduct a pooled meta-analysis comparing acute uncomplicated TBAD patient outcomes associated with primary TEVAR or BMT treatment. Relevant articles published up to July 2023 were identified by searching the Web of Science, PubMed, and Wanfang databases. Pooled analyses of endpoints from these studies were then conducted. Six relevant studies were included in this meta-analysis, involving 522 and 535 patients who underwent TEVAR and BMT treatment, respectively. No significant differences were observed between these two groups with respect to pooled hospitalization duration, re-intervention rates, early mortality, organ failure incidence, stroke incidence, or the incidence of retrograde type A dissection (p = 0.89, 0.12, 0.09, 0.36, 0.09, and 0.95, respectively). TEVAR, however, was associated with significantly better pooled thrombosed/obliterated false lumen, late mortality, aorta-related mortality, and rupture rates relative to BMT (p = 0.00001, 0.002, 0.0001, and 0.04, respectively). TEVAR was associated with a 7% pooled type I endoleak incidence rate. Endpoints exhibiting significant heterogeneity included hospitalization duration, thrombosed/obliterated false lumen rates, and rupture rates (I 2 = 96%, 73%, and 61%, respectively). While TEVAR and BMT yield similar short-term outcomes for acute uncomplicated TBAD patients, TEVAR may be associated with a better long-term patient prognosis.

Abstract 12150: Acute Type B Aortic Dissection a 15-Year, Single-Center Experience

Introduction: Treatment of acute type B aortic dissection (ATBAD) has evolved with the use of endovascular technology. This study evaluates the short and long-term outcomes of patients with ATBAD over a 15-year period. Methods: A retrospective review identified patients with ATBAD at our institution between 2006 and 2020. Patients were analyzed based on presentation status (complicated vs. uncomplicated) and treatment. Complicated ATBAD (cATBAD) included malperfusion of any vascular bed, intractable pain, rupture, or rapid expansion. Postoperative outcomes were evaluated within the initial 30 days after diagnosis when managed medically or within thirty days of surgical intervention. Descriptive statistics was performed to assess short-term outcomes. Kaplan-Meier survival was performed to assess long-term mortality. Results: A total of 296 patients presented with ATBAD in the study period. Out of those, 121 patients presented with cATBAD, while 175 patients presented with uncomplicated ATBAD (uATBAD). Out of the cATBAD group, 89 were treated with TEVAR, and 32 were treated with medication only. The cATBAD group was younger than the uCTBAD group (62.0 vs. 65.2, p=0.05). Early mortality was more common in cATBAD than uATBAD (9.9% vs 2.3%, p=0.013). When comparing cATBAD who underwent TEVAR vs conservative medical management, early mortality was higher in the medication only group (12.5% vs 9.0% p = 0.013). Permanent paraplegia occurred in 1.1% (1/89)of patients undergoing TEVAR. Kaplan-Meier survival analysis demonstrated no significant difference in long-term mortality between the cATBAD and uATBAD groups (Logrank p = 0.23). Among the uATBAD patients, 10.3% (18/175) required future intervention for type B dissection (12 TEVAR, 6 open). Among the TEVAR patients, 20.2% (18/89) required re-operations (11 endovascular repairs, 7 open). Conclusions: ATBAD is associated with significant morbidity and mortality, especially in the setting of a complicated presentation. While uATBAD is associated with better short-term outcomes, the diminishing difference in long-term outcome between cATBAD and uATBAD calls for reevaluation of our indications for intervention and may suggest that the remodeling associated with TEVAR could have long term benefit.

Abstract 10736: Statistical Shape Modeling Reveals Anatomic Shape Features Associated With the Outcome of Optimal Medical Therapy in Uncomplicated Type B Aortic Dissection

Introduction: Currently, Type B aortic dissection (TBAD) without the presence of either organ malperfusion or aortic rupture is managed with optimal medical therapy (OMT) consisting of an aggressive anti-hypertensive medical regimen and surveillance imaging. Although OMT achieves excellent early survival, the long-term outcomes with OMT alone remain poor. In this study, we identified anatomic shape features that correlate with OMT failure and aortic growth rates in uncomplicated TBAD via statistical shape modeling (SSM). Methods: Contrast CT scans of patients with acute uncomplicated TBAD were analyzed from 25 patients who were initially treated with OMT. OMT failure was defined as aortic intervention (surgical or endovascular repair, n = 8). Statistical shape models were constructed using principal component analysis (PCA) and partial least square regression (PLSR) to extract anatomic shape features from the aorta and flap geometries. For 14 of the 25 patients, additional follow-up CT scans (5 to 117 months) were used to quantify the rate of aortic expansion. Results: Four PCA (feature 5: p = 0.048, 12: p = 0.005, 14: p = 0.047, 24: p = 0.038) and two PLSR (feature 1: p = 0.000, 2: p = 0.004) shape features were effective at separating OMT failure patients and patients who were adequately treated with OMT. Two PCA features were moderately correlated with aortic growth rate (correlation coefficient, feature 11; r = 0.579, 21: r = 0.503). A PLSR feature was correlated with the growth rate (r = 0.867). Representative shape features are shown in Figure 1. Conclusions: Anatomic shape features extracted from SSM were correlated with the outcomes of OMT and aortic growth rate. SSM shape features may provide additional anatomic risk factors in addition to aortic diameter that predicts aneurysmal degeneration and the need for surgical intervention. Future investigations will incorporate the SSM shape features to determine the risk of OMT failure in uncomplicated TBAD patients.

Endovascular Repair of the Thoracic Aorta Combined with Drug Therapy in Acute Uncomplicated Type B Aortic Dissection.

Objective This study was to evaluate the clinical efficacy of thoracic endovascular aortic repair (TEVAR) combined with Best Medical Therapy (BMT) in acute uncomplicated type B aortic dissection (TBAD). Methods Using the random method, 90 patients admitted to our hospital between January 2018 and January 2020 with acute uncomplicated TBAD were randomly divided into a control group and a study group, with 45 cases in each of the groups. The effectiveness of BMT combined with TEVAR treatment was compared. Results The incidence of recent adverse reactions did not differ significantly between the two groups. Compared to the control group, the 1-year survival rate and 2-year survival rate of patients in the study group were considerably higher. In order to examine the relationship between survival and time, the Kaplan-Meier curve was used. Both groups reached the median survival time after 24 months of follow-up. The expected survival time of the study group was longer than that of the control group. False lumen thrombosis or absence of thrombus was significantly more prevalent in the study group than in the control group. Conclusion For patients with acute uncomplicated TBAD, BMT combined with TEVAR can significantly improve the long-term survival rate and increase the expected survival time.

Changes in aortic growth rate and factors influencing aneurysmal dilatation after uncomplicated acute type B aortic dissection.

OBJECTIVESThe aim of this study was to evaluate changes in aortic growth rate and factors influencing aneurysmal dilatation after uncomplicated acute type B aortic dissection (ABAD).METHODSMedically treated patients with uncomplicated ABAD between September 2004 and January 2020 were retrospectively reviewed. Diameters of 6 different sites in the descending aorta were measured and aortic growth rate was calculated according to the time interval. Factors associated with aneurysmal changes were also investigated.RESULTSThis study enrolled a total of 105 patients who underwent >2 serial computed tomography with a mean follow-up duration of 35.4 (12.1–77.4) months. The mean overall growth rates of the proximal descending thoracic aorta (DTA), mid-DTA, distal DTA, proximal abdominal aorta, maximal DTA and maximal abdominal aorta were 0.6 (1.9), 2.9 (5.2), 2.1 (4.0), 1.2 (2.2), 3.3 (5.6) and 1.4 (2.5) mm/year, respectively. The growth rate was higher at the early stage. It decreased over time. Growth rates of proximal DTA, mid-DTA, distal DTA, proximal abdominal aorta, maximal DTA, and maximal abdominal aorta within 3 months after dissection were 1.3 (9.6), 12.6 (18.2), 7.6 (11.7), 5.9 (7.5), 16.7 (19.8) and 6.8 (8.9) mm/year, respectively. More than 2 years later, they were 0.2 (0.6), 1.6 (1.6), 1.2 (1.3), 0.9 (1.4), 1.7 (1.9) and 1.2 (1.7) mm/year, respectively. Factors associated with aneurysmal changes after uncomplicated ABAD included an elliptical true lumen (odds ratio = 3.16; 95% confidence interval: 1.19–8.41; P = 0.021) and a proximal entry >10 mm (odds ratio = 3.08; 95% confidence interval: 1.09–8.69; P = 0.034) on initial computed tomography imaging.CONCLUSIONSThe aortic growth rate was higher immediately after uncomplicated ABAD but declined eventually. Patients with an elliptical true lumen and a large proximal entry might be good candidates for early endovascular intervention after uncomplicated ABAD.

Intensive care unit management of uncomplicated type B aortic dissection in relation to treatment period: a retrospective observational study.

BackgroundMedical therapy is the standard treatment for uncomplicated acute type B aortic dissection (ATBAD), but there is little evidence of the need for intensive care unit (ICU) management. Therefore, we aimed to investigate the effects of ICU treatment on uncomplicated ATBAD.MethodsWe retrospectively studied patients with uncomplicated ATBAD who were medically treated between January 2010 and July 2020. Patients were divided into short-term ICU stay (SIS) and long-term ICU stay (LIS) groups, according to a 48-hour cutoff of ICU stay duration. The incidence of pneumonia and delirium, rate of aortic events, hospital mortality, and survival rate were compared.ResultsFifty-five patients were treated for uncomplicated ATBAD (n=29 for SIS and n=26 for LIS). The incidence of pneumonia (3.6% vs. 7.7%) and delirium (14.3% vs. 34.6%) was higher in the LIS group than in the SIS group, but the differences were not statistically significant. The survival rates at 1, 3, and 5 years were not different between the two groups (SIS: 96.4%, 92.2%, and 75.5% vs. LIS: 96.2%, 88.0%, and 54.2%, respectively; p=0.102). Multivariate Cox regression analysis for aortic events showed that using a calcium channel blocker lowered the risk of aortic events.ConclusionLong-term ICU treatment is unlikely to be necessary for the treatment of uncomplicated ATBAD. Active use of antihypertensive agents, such as calcium channel blockers, may be needed during the follow-up period.

Effect of Timing of Thoracic Endovascular Aneurysm Repair After Type B Aortic Dissection in the Society for Vascular Surgery Vascular Quality Initiative Postapproval Project for Dissection

The timing of thoracic endovascular aneurysm repair after the onset of uncomplicated acute type B aortic dissection (UATBAD) remains controversial. The objective of this study was to evaluate the Society for Vascular Surgery Vascular Quality Initiative (VQI) postapproval study data for the impact of thoracic endovascular aneurysm repair timing for UATBAD on early and late outcomes, including mortality, procedural complications, and long-term reintervention.

Timing of endovascular repair impacts long-term outcomes of uncomplicated acute type B aortic dissection

ObjectiveTo compare the 5-year outcomes of acute versus subacute thoracic endovascular aortic repair (TEVAR) in patients with uncomplicated acute type B aortic dissection (ATBAD). MethodsBetween March 2008 and September 2018, 238 consecutive patients with uncomplicated ATBAD underwent TEVAR in the acute or subacute phase and were analyzed retrospectively. The primary end points were all-cause death and aortic-related death. The secondary end point was a composite of the outcomes of death from any cause, rupture, new dissection, retrograde type A aortic dissection, endoleak, and late reintervention. Inverse probability treatment weighting was used to balance baseline characteristics. Weight-adjusted Kaplan-Meier estimate with landmark analysis and weighted Cox model were performed to assess time-to-event outcomes. ResultsIn the inverse probability treatment weighting-adjusted population, the 30-day mortality was 1.5% in the acute TEVAR group and 0% in the subacute TEVAR group (P = .24). The incidence of 30-day adverse events occurred in 16.8% and 6.9% patients in the acute TEVAR and subacute TEVAR groups, respectively (P = .13). At 5 years, there was no statistically significant difference in all-cause death (hazard ratio [HR], 1.50; 95% confidence interval [CI], 0.59-3.81; P = .39) and aortic-related death (HR, 1.11; 95% CI, 0.34-3.60; P = .86) between the two groups. The composite outcomes occurred in 30 patients (23.0%) in the acute TEVAR group and 18 patients (22.3%) in the subacute TEVAR group, respectively (HR, 0.67; 95% CI, 0.36-1.25; P = .20). However, a landmark analysis of the composite outcomes indicated that there was a significant interaction between treatment effect and time (Pinteraction = .01), with a significantly higher incidence of the composite outcomes in the acute TEVAR group compared with the subacute TEVAR group within 1 year (HR, 0.25; 95% CI, 0.08-0.79; P = .02), and a comparable rate between 1 and 5 years (HR, 1.25; 95% CI, 0.56-2.76; P = .59). ConclusionsAt the 5-year follow-up, no significant differences exist in the all-cause death and aortic-related death between acute and subacute TEVAR. However, acute TEVAR is associated with an increased rate of severe complications within 1 year, which suggests that performing TEVAR in the subacute phase of ATBAD may be the preferable option.

Early Thoracic Endovascular Aortic Repair is Superior to Medical Therapy in Acute Uncomplicated Type B Aortic Dissection

Historically, treatment of acute type B aortic dissection (TBAD) has been primarily medical management via impulse control, with intervention reserved for complicated presentations. At present, early usage of thoracic endovascular aortic repair (TEVAR) has been increasing to treat TBAD. The primary aim of the present study was to evaluate readmissions and treatment failure of TEVAR vs medical management alone as the initial treatment strategy for acute uncomplicated TBAD.

Early Thoracic Endovascular Aortic Repair Is Superior to Medical Therapy for Acute Uncomplicated Type B Aortic Dissection

Historically, treatment of acute type B aortic dissection (TBAD) has primarily been medical management via impulse control, with intervention reserved for complicated presentations. At present, the early use of thoracic endovascular aortic repair (TEVAR) to treat TBAD has been increasing. The primary aim of the present study was to evaluate readmissions and treatment failure of TEVAR vs medical management alone as the initial treatment strategy for acute uncomplicated TBAD.

Wall Shear Stress Assessment of the False Lumen in Acute Type B Aortic Dissection Visualized by 4-Dimensional Flow Magnetic Resonance Imaging: An Ex-Vivo Study.

Four-dimensional flow magnetic resonance imaging (4D flow MRI) can accurately visualize and quantify flow and provide hemodynamic information such as wall shear stress (WSS). This imaging technique can be used to obtain more insight in the hemodynamic changes during cardiac cycle in the true and false lumen of uncomplicated acute Type B Aortic Dissection (TBAD). Gaining more insight of these forces in the false lumen in uncomplicated TBAD during optimal medical treatment, might result in prediction of adverse outcomes. A porcine aorta dissection model with an artificial dissection was positioned in a validated ex-vivo circulatory system with physiological pulsatile flow. 4D flow MR images with 3 set heartrates (HR; 60 bpm, 80 bpm and 100 bpm) were acquired. False lumen volume per cycle (FLV), mean and peak systolic WSS were determined from 4D flow MRI data. For validation, the experiment was repeated with a second porcine aorta dissection model. During both experiments an increase in FLV (initial experiment: ΔFLV = 2.05 ml, p < 0.001, repeated experiment: ΔFLV = 1.08 ml, p = 0.005) and peak WSS (initial experiment: ΔWSS = 1.2 Pa, p = 0.004, repeated experiment: ΔWSS = 1.79 Pa, p = 0.016) was observed when HR increased from 60 to 80 bpm. Raising the HR from 80 to 100 bpm, no significant increase in FLV (p = 0.073, p = 0.139) was seen during both experiments. The false lumen mean WSS increased significant during initial (2.71 to 3.85 Pa; p = 0.013) and non-significant during repeated experiment (3.22 to 4.00 Pa; p = 0.320). 4D flow MRI provides insight into hemodynamic dimensions including WSS. Our ex-vivo experiments showed that an increase in HR from 60 to 80 bpm resulted in a significant increase of FLV and WSS of the false lumen. We suggest that strict heart rate control is of major importance to reduce the mean and peak WSS in uncomplicated acute TBAD. Because of the limitations of an ex-vivo study, 4D flow MRI will have to be performed in clinical setting to determine whether this imaging model would be of value to predict the course of uncomplicated TBAD.

Effect of intimal flap motion on flow in acute type B aortic dissection by using fluid‐structure interaction

A monolithic, fully coupled fluid-structure interaction (FSI) computational framework was developed to account for dissection flap motion in acute type B aortic dissection (TBAD). Analysis of results included wall deformation, pressure, flow, wall shear stress (WSS), von Mises stress and comparison of hemodynamics between rigid wall and FSI models. Our FSI model mimicked realistic wall deformation that resulted in maximum compression of the distal true lumen (TL) by 21.4%. The substantial movement of intimal flap mostly affected flow conditions in the false lumen (FL). Flap motion facilitated more flow entering the FL at peak systole, with the TL to FL flow split changing from 88:12 in the rigid model to 83:17 in the FSI model. There was more disturbed flow in the FL during systole (5.8% FSI vs 5.2% rigid) and diastole (13.5% FSI vs 9.8% rigid), via a λ2 -criterion. The flap-induced disturbed flow near the tears in the FSI model caused an increase of local WSS by up to 70.0% during diastole. This resulted in a significant reduction in the size of low time-averaged WSS (TAWSS) regions in the FL (113.11 cm2 FSI vs 177.44 cm2 rigid). Moreover, the FSI model predicted lower systolic pressure, higher diastolic pressure, and hence lower pulse pressure. Our results provided new insights into the possible impact of flap motion on flow in aortic dissections, which are particularly important when evaluating hemodynamics of acute TBAD. NOVELTY STATEMENT: Our monolithic fully coupled FSI computational framework is able to reproduce experimentally measured range of flap deformation in aortic dissection, thereby providing novel insights into the influence of physiological flap motion on the flow and pressure distributions. The drastic flap movement increases the flow resistance in the true lumen and causes more disturbed flow in the false lumen, as visualized through the λ2 criterion. The flap-induced luminal pressure is dampened, thereby affecting pressure measures, which may serve as potential prognostic indicators for late complications in acute uncomplicated TBAD patients.

Timing of thoracic endovascular aortic repair for uncomplicated acute type B aortic dissection and the association with complications

ObjectivePrevious publications have clearly established a correlation between timing of thoracic endovascular aortic repair (TEVAR) and complications after treatment of complicated acute type B aortic dissection (ATBAD). However, the temporal association of TEVAR with morbidity after uncomplicated presentations is poorly understood and has not previously been examined using real-world national data. Therefore, the objective of this analysis was to determine whether TEVAR timing of uncomplicated ATBAD (UATBAD) is associated with postoperative complications. MethodsThe Vascular Quality Initiative TEVAR and complex endovascular aneurysm repair registry was analyzed from 2010 to 2019. Procedures performed for non-dissection-related disease as well as for ATBAD with malperfusion or rupture were excluded. Because of inherent differences between timing cohorts, propensity score matching was performed to ensure like comparisons. Univariate and multivariable analysis after matching was used to determine differences between timing groups (symptom onset to TEVAR: acute, 1-14 days; subacute, 15-90 days) for postoperative mortality, in-hospital complications, and reintervention. ResultsA total of 688 cases meeting inclusion criteria were identified. After matching 187 patients in each of the 1- to 14-day and 15- to 90-day treatment groups, there were no statistically significant differences between groups. On univariate analysis, the 1- to 14-day treatment group had a higher proportion of cases requiring reintervention within 30 days (15.3%) compared with UATBAD patients undergoing TEVAR within 15 to 90 days (5.2%; P = .02). There was also a difference (P = .007) at 1 year, with 33.8% of the 1- to 14-day UATBAD patients undergoing reintervention compared with 14.5% for the 15- to 90-day group. There were no statistically significant differences on multivariable analysis for long-term survival, complications, or long-term reintervention. There was a trend toward significance (P = .08) with the 1- to 14-day group having 2.3 times the odds of requiring an in-hospital reintervention compared with the 15- to 90-day group. ConclusionsTiming of TEVAR for UATBAD does not appear to predict mortality or postoperative complications. However, there is a strong association between repair within 1 to 14 days and higher risk of reintervention. This may in part be related to the 1- to 14-day group's representing an inherently higher anatomic or physiologic risk population that cannot be entirely accounted for with propensity analysis. The role of optimal timing to intervention should be incorporated into future study design of TEVAR trials for UATBAD.

Effect of Thoracic Endovascular Aortic Repair on Aortic Remodeling in Patients with Type B Aortic Dissection in an Asian Population

Management of uncomplicated type B aortic dissection (TBAD) has traditionally been aggressive medical therapy. Recent studies brought about a paradigm shift with evidence to suggest benefits from early endovascular intervention to a high risk subgroup of acute uncomplicated TBAD patients. We aim to review the effects of aortic remodeling in Asian patients with TBAD with and without endovascular intervention, including maximal aortic diameter, true lumen diameter, and false lumen thrombosis. This is a single-center retrospective study of a prospective database. Patients who presented to our institution with acute TBAD from January 2008 to December 2015 (n=44) were evaluated. Eighteen percent (8 patients) presented with complicated TBAD and underwent emergency thoracic endovascular aortic repair (TEVAR) while the remaining 82% (36 patients) were treated with optimal medical therapy (OMT). Six patients under the conservative arm crossed over to elective TEVAR after 6weeks because of interval radiological progression of disease. There was no significant difference in the baseline demographics of the TEVAR group and the OMT group. At 24 months, mean maximal aortic diameter difference was -7.7mm and +1.9mm (P=0.077), mean true lumen diameter difference was +10.0mm and +2.6mm (P=0.049), and false lumen thrombosis was 100% and 20% (P=0.012) for TEVAR and OMT, respectively. Kaplan-Meier analysis showed no significant difference in mortality between the 2 groups at 30 days and 2 years. Within an Asian population with TBAD, TEVAR with OMT has a significant positive effect on aortic remodeling, compared with OMT-only management.

Comparison of mid-term outcomes of endovascular repair and medical management in patients with acute uncomplicated type B aortic dissection

ObjectivesTo further assess the early and mid-term outcomes of thoracic endovascular aortic repair (TEVAR) in patients with acute uncomplicated type B aortic dissection (TBAD) compared with those receiving best medical treatment (BMT). MethodsBetween February 2008 and March 2018, 357 consecutive patients with acute uncomplicated TBAD were retrospectively analyzed. Among them, 191 patients underwent TEVAR, and 166 received BMT. After propensity score matching, we obtained 145 matched pairs for analysis. ResultsIn the matched population, the 30-day mortality between the TEVAR group and the BMT group showed no statistically significant difference, whereas the early adverse events rates in the TEVAR group were significantly greater than that of the BMT group (P = .003). Freedom from all-cause mortality in the TEVAR group was significantly greater than that of the BMT group (TEVAR: 91.9% at 5 years, BMT: 82.2% at 5 years, P = .028). Freedom from aortic-related mortality in the TEVAR group was significantly greater than that of the BMT group (TEVAR: 94.1% at 5 years, BMT: 86.1% at 5 years, P = .044). Multivariable Cox-hazard regression analysis demonstrated that the older age (hazard ratio [HR], 1.04; 95% confidence interval [CI], 1.01-1.08, P = .013), BMT (HR, 2.33; 95% CI, 1.08-5.05, P = .032), and the distance between the primary entry tear and the left subclavian artery <2.0 cm (HR, 2.30; 95% CI, 1.06-4.99, P = .035) were the significant risk factors for all-cause death. Given death as a competing factor, the cumulative incidence of rupture in the BMT group was significantly greater than that of the TEVAR group (BMT: 13.7% at 5 years, TEVAR: 5.1% at 5 years, P = .024). ConclusionsDespite more complications in the early stage, TEVAR was associated with decreased risk of late death and had fewer late aortic ruptures compared with BMT in patients with acute uncomplicated TBAD. Therefore, TEVAR may be considered as the first option to improve the late outcomes in these patients.