Impact of Non-Diameter Aortic Indices on Surgical Eligibility: Results from the TITAN: SvS Randomized Controlled Trial.

OBJECTIVES: Traditional criteria for intervention on an asymptomatic ascending aortic aneurysm has been a maximal aortic diameter of ⩾5.5cm. The 2022 ACC/AHA aortic guidelines adopted cross-sectional aortic area/height ratio, aortic size index (ASI) and aortic height index (AHI) as alternate parameters for surgical intervention. The objective of this study was to evaluate the impact of using these newer indices on patient eligibility for surgical intervention in a prospective, multicenter cohort with moderate sized ascending aortic aneurysms between 5.0-5.4 cm. METHODS: Patients enrolled from 2018 to 2023 in the randomization or registry arms of the multicenter trial, TITAN: SvS, were included in the study. Clinical data was captured prospectively in an online database. Imaging data were derived from a core CT lab. RESULTS: Among the 329 included patients, 20% were female. Mean age was 65.0 ± 11.6 years and mean maximal aortic diameter was 50.8 ±3.9 mm. In the one third of all patients (n=109) who met any one of the three criteria (i.e., ASI ⩾ 3.08 cm/m2, AHI ⩾ 3.21 cm/m or cross-sectional aortic area/height ⩾ 10 cm2/m), their mean maximal aortic diameter was 52.5 ±0.52 mm. Alternate criteria were most commonly met in females compared to males: 20% versus 2% for ASI (p<0.001), 39% versus 5% for AHI (p<0.001) and 39% versus 21% for cross-sectional aortic area/height (p=0.002), respectively. CONCLUSIONS: One third of patients in Titan:SvS would meet criteria for surgical intervention based on novel parameters vs. the classic definition of diameter⩾5.5cm. Surgical thresholds for ASI, AHI or cross-sectional aortic area/height ratio are more likely to be met in female patients compared to male patients.

Retrograde Cerebral Perfusion May Decrease Stroke Risk During Elective Aortic Arch Surgery.

OBJECTIVE: Controversy remains regarding the optimal neuroprotection strategy for elective hemiarch replacement (HEMI). This study sought to compare outcomes in patients who underwent HEMI utilizing the 2 most common contemporary methods of cerebral protection. METHODS: The ARCH international aortic database was queried, and 782 patients undergoing elective HEMI with circulatory arrest from 2007 to 2012 were identified. There were 418 patients who underwent HEMI using moderate hypothermia (nasopharyngeal temperature 20.1 to 28.0 °C) and antegrade cerebral perfusion (MHCA/ACP). There were 364 patients who underwent HEMI using deep hypothermia (nasopharyngeal temperature 14.1 to 20 °C) and retrograde cerebral perfusion (DHCA/RCP). Adverse outcomes were compared between the groups using both univariable and multivariable analyses. RESULTS: Patients who underwent MHCA/ACP were older (64 vs 61 years, P = 0.01) and more frequently had peripheral vascular disease than DHCA/RCP patients (28.5% vs 7.1%, P < 0.001). Patients in the DHCA/RCP group had a greater incidence of full aortic root replacement (55.8% vs 26.4%, P < 0.001) and more frequently had a central cannulation strategy (83% vs 55.7%, P < 0.001). Cardiopulmonary bypass (170 vs 157 min, P = 0.002) and aortic cross-clamp (134 vs 92 min, P < 0.001) times were significantly longer in the DHCA/RCP group. On univariable analysis, overall mortality was statistically similar between groups (MHCA/ACP 3.4% vs DHCA/RCP 2.3%, P = 0.47), but permanent neurologic deficits were significantly lower in the DHCA/RCP cohort (MHCA/ACP 3.9% vs DHCA/RCP 1.0%, P = 0.02). Multivariable analysis showed no difference in mortality nor perioperative stroke between perfusion cohorts. CONCLUSIONS: Both MHCA/ACP and DHCA/RCP are excellent neuroprotective strategies that produce low mortality in patients undergoing elective HEMI. DHCA/RCP may demonstrate theoretically improved neurologic outcomes compared with MHCA/ACP, but this topic warrants further study.

Knowledge, attitudes, and practice preferences in the surgical threshold for ascending aortic aneurysm among Canadian cardiac surgeons.

OBJECTIVE: The survey aimed to assess the practice patterns of Canadian cardiac surgeons on the size threshold at which patients with ascending aortic aneurysm would be offered surgery. METHODS: A 18-question electronic survey was electronically distributed to 148 practicing cardiac surgeons in Canada via email from January to August 2020. Questions presented clinical scenarios focusing on modifying a single variable, and respondents were asked to identify their surgical size threshold for each of the clinical scenarios. RESULTS: The individual response rate was 62.0% (91/148) and institutional response rate was 89.3% (25/29). For an incidental asymptomatic ascending aortic aneurysm in a 60-year-old otherwise-healthy male patient with a tricuspid aortic valve and bicuspid aortic valve of 1.9 m2, 20.2% of the respondents would recommend surgery when the aneurysm was <5.5 cm. A significant number of surgeons modified their surgical threshold in response to changes to BSA, bicuspid aortic valve, growth rate, age, occupation, symptom, and family history (P < .01). Notably, if the patient had a bicuspid aortic valve, 41.0% of respondents lowered their threshold for surgery, with only 43.0% recommending surgery at ≥5.5 cm (P < .01). CONCLUSIONS: Practice variations exist in the current size threshold for surgery of ascending aortic aneurysms in Canada. These differences between surgeons are further accentuated in the context of bicuspid aortic valve, smaller body stature, younger age, low growth rate, family history, and for the performance of isometric exercise. These represent important areas where future prospective studies are required to inform best practice.

Biomechanics in ascending aortic aneurysms correlate with tissue composition and strength.

Objective: This study correlates low strain tangential modulus (LTM) and transition zone onset (TZo) stress, biomechanical parameters that occur within the physiological range of stress seen in vivo, with tissue strength and histopathologic changes in aneurysmal ascending aortic tissue. Method: Ascending aortic aneurysm tissue samples were collected from 41 patients undergoing elective resection. Samples were subjected to planar biaxial testing to quantify LTM and TZo. These were then correlated with strength assessed from uniaxial testing and with histopathologic quantification of pathologic derangements in elastin, collagen, and proteoglycan (PG). Results: Decreased LTM and TZo were correlated with reduced strength (P < .05), PG content (P < .05), and elastin content (P < .05). Reduced TZo also was correlated with increased elastin fragmentation (P < .05). Conclusions: LTM and TZo are correlated with common biomechanical and histopathologic alterations in ascending aortic aneurysm tissue that are thought to relate to the risk of acute aortic syndromes. LTM and TZo are measured under conditions approximating in vivo physiology and have the potential to be obtained noninvasively using medical imaging techniques. Therefore, they represent parameters that warrant future study as potential contributors to our growing knowledge of pathophysiology, disease progression, and risk stratification of aortic disease.

Management of acute type A aortic dissection in the elderly: an analysis from IRAD.

OBJECTIVES: We sought to examine management and outcomes of (Stanford) type A aortic dissection (TAAAD) in patients aged >70 years. METHODS: All patients with TAAAD enrolled in the International Registry of Acute Aortic Dissection database (1996-2018) were studied (n = 5553). Patients were stratified by age and therapeutic strategy. Outcomes for octogenarians were compared with those for septuagenarians. Variables associated with in-hospital mortality were identified by multivariable logistic regression. RESULTS: In-hospital mortality for all patients (all ages) was 19.7% (1167 deaths), 16.1% after surgical intervention vs 52.1% for medical management (P < 0.001). Of the study population, 1281 patients (21.6%) were aged 71-80 years and 475 (8.0%) were >80 years. Fewer octogenarians underwent surgery versus septuagenarians (68.1% vs 85.9%, P < 0.001). Overall mortality was higher for octogenarians versus septuagenarians (32.0% vs 25.6%, P = 0.008); however, surgical mortality was similar (25.1% vs 21.7%, P = 0.205). Postoperative complications were comparable between surgically managed cohorts, although reoperation for bleeding was more common in septuagenarians (8.1% vs 3.2%, P = 0.033). Kaplan-Meier 5-year survival was significantly superior after surgical repair in all age groups, including septuagenarians (57.0% vs 13.7%, P < 0.001) and octogenarians (35.5% vs 22.6%, P < 0.001). CONCLUSIONS: When compared with septuagenarians, a smaller percentage of octogenarians undergo surgical repair for TAAAD, even though postoperative outcomes are similar. Age alone should not preclude consideration for surgery in appropriately selected patients with TAAAD.

Neuroanatomy and severity of stroke in patients with type A aortic dissection.

BACKGROUND: Strokes are a longstanding complication of acute type A aortic dissection (ATAAD) repair. Understanding the neuroanatomy, mechanism, and severity of stroke will facilitate efforts to improve prediction, prevention, and treatment strategies. METHODS: Retrospective review of patients who sustained stroke from a consecutive series of patients undergoing ATAAD repair. Neuroimaging was interpreted by two stroke neurologists blinded to clinical results. Severity of stroke was assessed by the National Institutes of Health Stroke Scale (NIHSS). Residual disability at 30 days was assessed using the modified Rankin Scale (mRS). RESULTS: Twenty percent (38/189) of patients undergoing repair for ATAAD had stroke (unilateral 58%, bi-hemispheric 42% [p = .33]). All strokes were ischemic. No significant lateralization (right vs. left) was noted with unilateral strokes (26% vs. 32%, p = .67). Etiology of stroke was embolic (58%), hypoperfusion (26%), mixed (11%), and unknown (5%). There were no intraoperative variables that correlated with the neuroanatomy or mechanism of stroke. Preoperative carotid dissection was seen in 40% (n = 15), while postoperatively 10% (n = 4) sustained intracranial large vessel occlusion (LVO). Strokes were moderate or severe (NIHSS ≥ 9) in 97% of cases, with 66% incidence of moderate residual disability (mRS ≥ 3) at 1 month postoperatively. CONCLUSIONS: Strokes associated with ATAAD are severe at presentation resulting in significant disability. One in 10 strokes is due to LVO and potentially amenable to endovascular treatment. Heterogeneity in both location and etiology of stroke makes prevention challenging. Future trials may evaluate the role of early neuroimaging and simultaneous treatment of stroke given advancements in endovascular therapy.

Biomechanical properties of ascending aortic aneurysms: Quantification of inter- and intra-patient variability.

This study investigates the biomechanical properties of ascending aortic aneurysms focusing on the inter-patient differences vs. the heterogeneity within a patient's aneurysm. Each specimen was tested on a biaxial testing device and the resulting stress-strain response was fitted to a four-parameter Fung constitutive model. We postulate that the inter-patient variability (differences between patients) blurs possible intra-patient variability (regional heterogeneity) and, thus, that both effects must be considered to shed light on the role of heterogeneity in aneurysm progression. We propose, demonstrate, and discuss two techniques to assess differences by, first, comparing conventional biomechanical properties and, second, the overall constitutive response. Results show that both inter- and intra-patient variability contribute to errors when using population averaged models to fit individual tissue behaviour. When inter-patient variability was accounted for and its effects excluded, intra-patient heterogeneity could be assessed, showing a wide degree of heterogeneity at the individual patient level. Furthermore, the right lateral region (from the patient's perspective) appeared different (stiffer) than the other regions. We posit that this heterogeneity could be a consequence of maladaptive remodelling due to altered loading conditions that hastens microstructural changes naturally occurring with age. Further validation of these results should be sought from a larger cohort study.

Development of Quality Indicators for the Management of Acute Type A Aortic Dissection.

In an effort to further improve surgical outcomes in patients with acute type A aortic dissection (ATAD), the Canadian Thoracic Aortic Collaborative (CTAC), with the support of the Canadian Society of Cardiac Surgeons (CSCS), endeavoured to develop quality indicators (QIs) for the management of patients with ATAD. After 2 successive consultations with the CTAC membership, 11 QIs were selected and separated into 5 broad categories: preoperative (time from presentation to diagnosis, time from presentation to the operating room), intraoperative (use of hypothermic circulatory arrest and antegrade cerebral perfusion), 30-day outcomes (30-day rates of all-cause mortality, 30-day rates of new postoperative stroke), 1-year outcomes (1-year rates of follow-up imaging, 1-year rates of all-cause mortality, and 1-year rates of surgical reintervention), and institutional (institutional surgical volumes, individual surgical volumes, and presence of institutional aortic disease teams). The purpose of this article is to describe the process by which QIs for the management of ATAD were developed and the feasibility by which they may be collected using existing clinical and administrative data sources. Furthermore, we demonstrate how they may be used to evaluate success following surgery for repair of ATAD and ultimately improve clinical outcomes.

Transthoracic aorto-axillary extra-anatomical bypass for difficult subclavian artery revascularization: a multicenter patency study.

In situ revascularization of the subclavian artery can be challenging in the context of emergency situations, a large aortic aneurysm with a posteriorly displaced left subclavian artery, a complex redo procedure or in the presence of an aberrant subclavian artery. A transthoracic aorto-axillary extra-anatomical bypass is a low risk alternative to in situ revascularization or carotid to subclavian bypass. We herein describe the surgical steps during a single-stage surgery complex aortic arch surgery. We report a 95.3% graft patency for 77 consecutive transthoracic aorto-axillary extra-anatomical bypass performed to 66 patients at the mean follow-up of 2.9 ± 2.4 years. We encountered 3 early (before 180 days postop) graft failures and no late graft failure. Graft failure had no clinical significance.

Protocol for a randomised controlled trial for Treatment in Thoracic Aortic Aneurysm: Surgery versus Surveillance (TITAN: SvS).

INTRODUCTION: Ascending thoracic aortic aneurysm (ATAA) is an asymptomatic condition that can lead to catastrophic events of rupture or dissection. Current guidelines are based on limited retrospective data and recommend surgical intervention for ATAA with a diameter of greater or equal to 5.5 cm. Treatment in Thoracic Aortic Aneurysm: Surgery versus Surveillance is the first prospective, multicentre, randomised controlled trial that compares outcomes of patients undergoing early elective ascending aortic surgery to patients undergoing medical surveillance. METHODS AND ANALYSIS: Patients between the ages of 18 and 80 with an asymptomatic ATAA between 5.0 cm and 5.4 cm in diameter are eligible for randomisation to early surgery or surveillance. Patients in the surgery group will be followed at 1 month after discharge, then annually for a minimum of 2 years and up to 5 years. Patients in the surveillance group will be followed annually from their index clinic visit for a minimum of 2 years and up to 5 years. The primary outcome is all-cause mortality at follow-up. A sample size of 618 subjects (309 in each group) will achieve an 80% power at a 0.047 significance level. ETHICS AND DISSEMINATION: This study has received Ottawa Health Science Network Research Ethics Board approval (Protocol 20180007-01H), which was most recently updated on 25 November 2020. The Research Ethics Board have granted approval to the study at 14 participating institutions, including the Ottawa Health Science Network Research Ethics Board. On completion of data analysis, the result of the trial will be presented at national and international conferences, and published in relevant journals, regardless of the finding of the trial. TRIAL REGISTRATION NUMBER: NCT03536312.

Multidimensional Analysis of Descending Aortic Growth After Acute Type A Aortic Dissection.

BACKGROUND: After repair of acute type A aortic dissection, typical geometric variables of conventional aortic surveillance focus on maximum diameter and its rate of growth, potentially missing important geometric changes elsewhere. We determined additional information provided by a semiautomated, 3-dimensional (3D), nonlinear growth model of the descending thoracic aorta after repair of type A aortic dissection. METHODS: Computed tomographic angiography data were retrospectively collected after hemiarch repair of type A aortic dissection. The descending aorta was systematically reconstructed to generate a 3D model made up of individual segments. The baseline and follow-up diameters were measured semiautomatically for each segment, and the nonlinear interval growth was determined. RESULTS: The fastest growing segment expanded at a rate of 3.8 mm/y (interquartile range, 2.2 to 5.4 mm/y) vs 0.6 mm/y (interquartile range, -0.3 to 1.7 mm/y) when measured at the original site of maximum diameter (P < .01). The maximum baseline diameter was a poor predictor of location with fastest growth (r = 0.10, P > .1). Using the society recommended growth limits, a greater proportion of patients would be considered "at risk" when assessed by our method vs conventional surveillance measures. CONCLUSIONS: Our model identifies areas of rapid aortic growth after repair of type A dissection that would likely be missed using current surveillance techniques. The increased precision, resolution, and reproducibility provided by our technique may improve on limitations of current surveillance techniques, provide novel geometric data on aortic remodeling, and contribute to the pursuit of a comprehensive patient-specific approach to aortic risk stratification.

Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) Reporting Standards for Type B Aortic Dissections.

This Society for Vascular Surgery/Society of Thoracic Surgeons (SVS/STS) document illustrates and defines the overall nomenclature associated with type B aortic dissection. The contents describe a new classification system for practical use and reporting that includes the aortic arch. Chronicity of aortic dissection is also defined along with nomenclature in patients with prior aortic repair and other aortic pathologic processes, such as intramural hematoma and penetrating atherosclerotic ulcer. Complicated vs uncomplicated dissections are clearly defined with a new high-risk grouping that will undoubtedly grow in reporting and controversy. Follow-up criteria are also discussed with nomenclature for false lumen status in addition to measurement criteria and definitions of aortic remodeling. Overall, the document provides a facile framework of language that will allow more granular discussions and reporting of aortic dissection in the future.

Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) reporting standards for type B aortic dissections.

This Society for Vascular Surgery/Society of Thoracic Surgeons (SVS/STS) document illustrates and defines the overall nomenclature associated with type B aortic dissection. The contents describe a new classification system for practical use and reporting that includes the aortic arch. Chronicity of aortic dissection is also defined along with nomenclature in patients with prior aortic repair and other aortic pathologic processes, such as intramural hematoma and penetrating atherosclerotic ulcer. Complicated vs uncomplicated dissections are clearly defined with a new high-risk grouping that will undoubtedly grow in reporting and controversy. Follow-up criteria are also discussed with nomenclature for false lumen status in addition to measurement criteria and definitions of aortic remodeling. Overall, the document provides a facile framework of language that will allow more granular discussions and reporting of aortic dissection in the future.

Valve-Sparing Root Replacement Versus Composite Valve Grafting in Aortic Root Dilation: A Meta-Analysis.

BACKGROUND: Aortic valve-sparing operations theoretically have fewer stroke and bleeding complications but may increase late reoperation risk versus composite valve grafts. METHODS: We meta-analyzed all studies comparing aortic valve-sparing (reimplantation and remodelling) and composite valve-grafting (bioprosthetic and mechanical) procedures. Early outcomes were all-cause mortality, reoperation for bleeding, myocardial infarction, and thromboembolism/stroke. Long-term outcomes included all-cause mortality, reintervention, bleeding, and thromboembolism/stroke. Studies exclusively investigating dissection or pediatric populations were excluded. RESULTS: A total of 3794 patients who underwent composite valve grafting and 2424 who underwent aortic valve-sparing procedures were included from 9 adjusted and 17 unadjusted observational studies. Mean follow-up was 5.8 ± 3.0 years. Aortic valve sparing was not associated with any difference in early mortality, bleeding, myocardial infarction, or thromboembolic complications. Late mortality was significantly lower after valve sparing (incident risk ratio, 0.68; 95% confidence interval [CI], 0.54-0.87; P < .01). Late thromboembolism/stroke (incident rate ratio, 0.36; 95% CI, 0.22-0.60; P < .01) and bleeding (incident rate ratio, 0.21; 95% CI, 0.11-0.42; P < .01) risks were lower after valve sparing. Procedure type did not affect late reintervention. CONCLUSIONS: Aortic valve sparing appears to be safe and associated with reduced late mortality, thromboembolism/stroke, and bleeding compared with composite valve grafting. Late durability is equivalent. Aortic valve sparing should be considered in patients with favorable aortic valve morphology.

Delayed dehiscence of modified mechanical Bentall 7 years postsurgery for Takayasu's arteritis.

Following aortic surgery for vasculitis, the incidence and duration of onset of anastomotic breakdown is unclear. A case is presented of a young female patient with Takayasu's arteritis (TA) who was found to have frank dehiscence of a modified Bentall repair 7 years after surgery. The case highlights (i) the lack of normal healing following aortic surgery in TA, and (ii) need to differentiate imaging protocols for patients with defined vasculitis as opposed to degenerative aortic conditions. A recommendation is made for appropriate surveillance imaging modality alternating between computed tomography and magnetic resonance imaging in the often young patient population affected by vasculitis.