Predictors of Stable Aortic Dimensions in Medically Managed Acute Aortic Syndromes

Factors Affecting False Lumen Thrombosis In Type B Aortic Dissection

BACKGROUND

Complete thrombosis of the false lumen facilitates remodeling of type B aortic dissection (TBAD). Morphological characteristics affect thrombosis in the false lumen.

OBJECTIVES

Discuss the factors present before admission that influence false lumen thrombosis in patients with TBAD.

METHODS

We studied 282 patients diagnosed with TBAD in our hospital between January 2008 and December 2017. We divided the subjects into a thrombotic group and a non-thrombotic group based on whether any thrombus was detectable in the false lumen. We analyzed the differences between the two groups with respect to clinical data, the vertical length of the dissection, and the diameter of the aorta. P values < 0.05 were considered statistically significantly different.

RESULTS

Significant differences between the thrombotic group and non-thrombotic group were found with respect to age (53.92 ± 11.40 vs. 50.36 ± 10.71, p = 0.009) and proportion of patients with renal insufficiency (7.83% vs. 16.38%, p = 0.026). In zones 3-9, the true lumen diameter of the thrombotic group was significantly larger than in the non-thrombotic group (p < 0.05). Binary logistic regression analysis showed that true lumen diameter in zone 5 and renal insufficiency were independent predictors of false lumen thrombosis.

CONCLUSIONS

Age and renal function were associated with thrombosis in the false lumen. Potentially, the difference between the diameter of the true lumen diameter and that of the false lumen may influence the thrombosis of the false lumen.

Twenty-five years of observations from the International Registry of Acute Aortic Dissection (IRAD) and its impact on the cardiovascular scientific community

OBJECTIVE

The International Registry of Acute Aortic Dissection (IRAD) celebrated its 25th anniversary in January 2021. This study evaluated IRAD's role in promoting the understanding and management of acute aortic dissection (AD) over these years.

METHODS

IRAD studies were identified, analyzed, and ranked according to their citations per year (c/y) to determine the most-cited IRAD studies and topics. A systematic search of the literature identified cardiovascular guidelines on the diagnosis and management of acute AD. Consequently, IRAD's presence and impact were quantified using these documents.

RESULTS

Ninety-seven IRAD studies were identified, of which 82 obtained more than 10 cumulative citations. The median c/y index was 7.33 (25th-75th percentile, 4.01-16.65). Forty-two studies had a greater than median c/y index and were considered most impactful. Of these studies, most investigated both type A and type B AD (n = 17, 40.5%) and short-term outcomes (n = 26, 61.9%). Nineteen guideline documents were identified from 26 cardiovascular societies located in Northern America, Europe, and Japan. Sixty-nine IRAD studies were cited by these guidelines, including 38 of the 42 most-impactful IRAD studies. Among them, partial thrombosis of the false lumen as a predictor of postdischarge mortality and aortic diameters as a predictor of type A occurrence were determined as most-impactful specific IRAD topics by their c/y index.

CONCLUSIONS

IRAD has had and continues to have an important role in providing observations, credible knowledge, and research questions to improve the outcomes of patients with acute AD.

Inter-observer variability of expert-derived morphologic risk predictors in aortic dissection

OBJECTIVES

Establishing the reproducibility of expert-derived measurements on CTA exams of aortic dissection is clinically important and paramount for ground-truth determination for machine learning.

METHODS

Four independent observers retrospectively evaluated CTA exams of 72 patients with uncomplicated Stanford type B aortic dissection and assessed the reproducibility of a recently proposed combination of four morphologic risk predictors (maximum aortic diameter, false lumen circumferential angle, false lumen outflow, and intercostal arteries). For the first inter-observer variability assessment, 47 CTA scans from one aortic center were evaluated by expert-observer 1 in an unconstrained clinical assessment without a standardized workflow and compared to a composite of three expert-observers (observers 2-4) using a standardized workflow. A second inter-observer variability assessment on 30 out of the 47 CTA scans compared observers 3 and 4 with a constrained, standardized workflow. A third inter-observer variability assessment was done after specialized training and tested between observers 3 and 4 in an external population of 25 CTA scans. Inter-observer agreement was assessed with intraclass correlation coefficients (ICCs) and Bland-Altman plots.

RESULTS

Pre-training ICCs of the four morphologic features ranged from 0.04 (-0.05 to 0.13) to 0.68 (0.49-0.81) between observer 1 and observers 2-4 and from 0.50 (0.32-0.69) to 0.89 (0.78-0.95) between observers 3 and 4. ICCs improved after training ranging from 0.69 (0.52-0.87) to 0.97 (0.94-0.99), and Bland-Altman analysis showed decreased bias and limits of agreement.

CONCLUSIONS

Manual morphologic feature measurements on CTA images can be optimized resulting in improved inter-observer reliability. This is essential for robust ground-truth determination for machine learning models.

KEY POINTS

• Clinical fashion manual measurements of aortic CTA imaging features showed poor inter-observer reproducibility. • A standardized workflow with standardized training resulted in substantial improvements with excellent inter-observer reproducibility. • Robust ground truth labels obtained manually with excellent inter-observer reproducibility are key to develop reliable machine learning models.

Chronic thoracoabdominal aortic dissection: endovascular options to obliterate the false lumen

Background

Persistent false lumen patency in chronic thoracoabdominal aortic dissections after thoracic endovascular aortic repair (TEVAR) contributes to negative aortic remodeling. We have previously described the evolution of various endovascular techniques to treat persistent false lumen perfusion including false lumen embolization. Objectives of this study are to describe endovascular techniques to obliterate the false lumen and present updated outcomes in a recent series of patients undergoing false lumen embolization for chronic aortic dissection.

Methods

From January 2018 to May 2021, 17 patients with chronic dissection underwent false lumen embolization with coils, iliac plugs, and nitinol plugs. This was often in conjunction with or following TEVAR and balloon fracture fenestration. Mean follow-up 354±324 days.

Results

After false lumen embolization there was no mortality, stroke, spinal cord ischemia, or visceral and limb ischemia. No patients required dialysis, though 1 (5.9%) did experience acute kidney injury. There was 1 (5.9%) patient that required endovascular re-intervention on the thoracoabdominal aorta. No patients underwent subsequent open surgical repair.

Conclusions

TEVAR with adjunctive false lumen embolization and balloon fracture fenestration are techniques to obliterate retrograde flow into the false lumen of chronic thoracoabdominal aortic dissections in appropriately selected patients.

Predictors of Long-Term Aortic Growth and Disease Progression in Patients with Aortic Dissection, Intramural Hematoma, and Penetrating Aortic Ulcer

BACKGROUND

We aimed to identify predictors of long-term aortic diameter change and disease progression in a population cohort of patients with newly diagnosed aortic dissection (AD), intramural hematoma (IMH), or penetrating aortic ulcer (PAU).

METHODS

We used the Rochester Epidemiology Project record linkage system to identify all Olmsted County, MN-USA, residents diagnosed with AD, IMH, and PAU (1995-2015). The endpoints were aortic diameter change, freedom from clinical disease progression (any related intervention, aortic aneurysm, new aortic syndrome, rupture or death) and disease resolution (complete spontaneous radiological disappear). Linear regression was used to assess aortic growth rate; predictors of disease progression were identified with Cox proportional hazards.

RESULTS

Of 133 incident cases, 46 ADs, 12 IMHs, and 28 PAUs with sufficient imaging data were included. Overall median follow-up was 8.1 years. Aortic diameter increase occurred in 40 ADs (87%, median 1.0 mm/year), 5 IMHs (42%, median 0.2 mm/year) and 14 PAUs (50%, median 0.4 mm/year). Symptomatic presentation (P = 0.045), connective tissue disorders (P = 0.005), and initial aortic diameter >42 mm (P = 0.013) were associated with AD growth rate. PAU depth >9 mm (P = 0.047) and female sex (P = 0.013) were associated with aortic growth rate in PAUs and IMHs. At 10 years, freedom from disease progression was 22% (95% CI 12-41) for ADs, 44% (95% CI 22-92) for IMHs, and 46% (95% CI 27-78) for PAUs. DeBakey I/IIIB AD (HR 3.09; P = 0.038), initial IMH aortic diameter (HR 1.4; P = 0.037) and PAU depth >10 mm (HR 3.92; P = 0.018) were associated with disease progression. No AD spontaneously resolved; resolution rate at 10 years was 22% (95% CI 0-45) for IMHs and 11% (95% CI 0-23) for PAUs.

CONCLUSIONS

Aortic growth and clinical disease progression are observed in most patients with aortic syndromes, while spontaneous resolution is uncommon. Predictors of aortic growth and disease progression may be used to tailor appropriate follow-up and eventual early intervention.

Anticoagulation and Antiplatelet Medications Do Not Affect Aortic Remodeling after Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

OBJECTIVE

There is a lack of evidence regarding the effect of anticoagulation and antiplatelet medications on aortic remodeling for aortic dissection after endovascular repair. We investigated whether anticoagulation and antiplatelet medications affect aortic remodeling after thoracic endovascular aortic repair (TEVAR) for Type B aortic dissection (TBAD).

METHODS

Records of the Vascular Quality Initiative TEVAR registry (2012-2020) were reviewed. Procedures performed for TBAD were included. Aortic reintervention, false lumen thrombosis of the treated aorta and all-cause mortality at follow-up were compared between patients treated with and without anticoagulation medications. A secondary analysis was performed to assess the effect of antiplatelet therapy in patients not on anticoagulation. Cox proportional hazards models were used to estimate the effect of anticoagulation and antiplatelet therapies on outcomes.

RESULTS

1,210 patients (mean age, 60.7±12.2 years; 825 (68%) males) were identified with a mean follow-up of 21.2±15.7 months (range 1-94 months). 166 (14%) patients were on anticoagulation medications at discharge and at follow-up. Patients on anticoagulation were more likely to be older (mean age, 65.5 vs 60 years; P<.001) and Caucasian (69% vs 55%; P=.003), with higher proportions of coronary artery disease (10% vs 3%; P<.001), congestive heart failure (10% vs 2%; P<.001) and chronic obstructive pulmonary disease (15% vs 9%; P=.017). There were no differences in the mean preoperative thoracic aortic diameter or the number of endografts used. At 18-month, the rates of aortic reinterventions (8% vs 9% log-rank P=.873), complete false lumen thrombosis (52% vs 45%; P=.175) and mortality (2.5% vs 2.7%; P=.209) were similar in patients with and without anticoagulation, respectively. Controlling for covariates with the Cox regression method, anticoagulation use was not independently associated with a decreased rates of complete false lumen thrombosis (hazard ratio (HR) 0.74; 95% confidence interval (CI), 0.5-1.1; P=.132), increased need for aortic reinterventions (HR 1.02; 95% CI, 0.62-1.68; P=.934), and mortality (HR 1.25; 95% CI, 0.64-2.47; P=.514). On a secondary analysis, antiplatelet medications did not affect the rates of aortic reintervention, complete false lumen thrombosis and mortality.

CONCLUSIONS

Anticoagulation and antiplatelet medications do not appear to negatively influence the midterm endpoints of aortic reintervention or death in patients undergoing TEVAR for TBAD. Moreover, it did not impair complete false lumen thrombosis. Anticoagulation and antiplatelet medications do not adversely affect aortic remodeling and survival in this population at midterm.

Role of Endoluminal Techniques in the Management of Chronic Type B Aortic Dissection

In recent guidelines of international societies, the most frequent indication for treatment after chronic type B aortic dissection (cTBAD) is aneurysmal dilatation. Endovascular repair is recommended in patients with moderate to high surgical risk or with contraindications to open repair. During the last decade, many advances have been made in the field of endovascular techniques and devices. The aim of this article is to address the current status of endoluminal techniques for the management of cTBAD including standard thoracic endovascular repair, new devices, fenestrated and branched abdominal aortic devices and false lumen occlusion techniques.

Device profile of the Zenith Dissection Endovascular System for aortic dissection

Introduction: Thoracic endovascular aortic repair has been increasingly used to treat type B aortic dissection (TBAD) when it is indicated, offering better outcome in terms of mortality and morbidity compared to open repair. Accepted goals for endovascular treatment of aortic dissections are the closure of the primary intimal entry tear, depressurization, and thrombosis of the false lumen. Areas covered: This is a descriptive review on the Zenith Dissection Endovascular System (Cook Medical Inc., Bloomington, IN) which is a modular system specifically designed to treat TBAD, consisting of a proximal component, the Zenith TX2 TAA Endovascular Graft, and a distal component, the Zenith Dissection Endovascular Stent. The distal stents are uncovered to avoid blockage of dominant spinal cord intercostal arteries and allow for the deployment of the stents across branch vessel origins as needed to treat the dissection. Expert opinion: The Zenith Dissection Endovascular System has already been used for the treatment of TBAD for the last decade mostly in experienced centers. Current evidence suggests that this is a feasible and safe technique with relative low early mortality and morbidity rates. It is important to highlight the potential benefit of Zenith Dissection Endovascular System on the remodeling the dissected aorta during the follow-up period.

Current evidence in predictors of aortic growth and events in acute type B aortic dissection

OBJECTIVES

Acute type B aortic dissection can have a stable course or evolve into aneurysm and subsequent adverse events. The aim of this systematic review was to analyze the morphologic predictors of an adverse course to establish their validity based on consistency of results.

METHODS

Fifty-one studies were included in this review, reporting on aortic size, false lumen (FL) size, primary entry tear (ET) size and location, status of FL thrombosis, number of ETs, branch vessels involvement, and FL longitudinal extent.

RESULTS

Some predictors showed good consistency, whereas others did not. Aortic size was the most investigated predictor. A larger diameter at presentation predicted worse outcomes, with few exceptions. Both FL size and size relative to true lumen size also predicted an adverse course, although a standardized measurement method was not used. Regarding primary ET size and location, evidence was sparse and somewhat conflicting. Although FL complete thrombosis was consistently associated with a more benign course, the role of partial thrombosis remained unclear and the concept of FL saccular formation might account for the inconsistency, but further evidence is needed. A higher number of re-entry tears was considered to be protective against false channel expansion, but results need to be confirmed. The predictive role of branch vessels involvement and FL longitudinal extent remain controversial.

CONCLUSIONS

Among several predictors of aortic growth and events in acute type B aortic dissection, controversial and even conflicting results have been described. Consistent evidence has been demonstrated only for two predictors: aortic size at presentation is associated with adverse events and total FL thrombosis has a protective role.