Type B Aortic Dissection in Young Individuals With Confirmed and Presumed Heritable Thoracic Aortic Disease

Risk of Type B Dissection in Marfan Syndrome: The Cornell Aortic Aneurysm Registry

BACKGROUND

With preventive aortic grafting decreasing the incidence of type A dissections in Marfan syndrome (MFS), most dissections are now type B, for which risk factors remain largely uncertain.

OBJECTIVES

We explored the determinants of type B dissection risk in a large, single-center MFS registry.

METHODS

Demographic and anthropometric features, cardiovascular disease, and surgical history were compared in patients with MFS with and without type B dissection.

RESULTS

Of 336 patients with MFS, 47 (14%) experienced a type B dissection (vs type A in 9%). Patients with type B dissection were more likely to have undergone elective aortic root replacement (ARR) (79 vs 46%; P < 0.001). Of the patients, 55% had type B dissection a mean of 13.3 years after ARR, whereas 45% experienced type B dissection before or in the absence of ARR; 41 patients (87%) were aware of their MFS diagnosis before type B dissection. Among those with predissection imaging, the descending aorta was normal or minimally dilated (<4.0 cm) in 88%. In multivariable analyses, patients with type B dissection were more likely to have undergone ARR and independent mitral valve surgery, to have had a type II dissection, and to have lived longer.

CONCLUSIONS

In our contemporary cohort, type B dissections are more common than type A dissections and occur at traditional nonsurgical thresholds. The associations of type B dissection with ARR, independent mitral valve surgery, and type II dissection suggest a more severe phenotype in the setting of prolonged life expectancy.

Association of genetic variants in ULK4 with the age of first onset of type B aortic dissection

Background: The association between autophagy, structural alterations of the aortic wall, and endothelial dysfunction in humans has yet to be fully elucidated. The family of ULK (UNC51-like) enzymes plays critical roles in autophagy and development. This study aimed to evaluate the association between ULK gene family members and patient age of first type B aortic dissection (TBAD) onset.

Methods: The genotype data in a TBAD cohort from China and the related summary-level datasets were analyzed. We applied the sequence kernel association test (SKAT) to test the association between single-nucleotide polymorphisms (SNPs) and age of first onset of TBAD controlling for gender, hypertension, and renal function. Next, we performed a 2-sample Mendelian randomization (MR) to explore the potential causal relationship between ULK4 and early onset of TBAD at the level of gene expression coupled with DNA methylation with genetic variants as instrumental variables.

Results: A total of 159 TBAD patients with 1,180,097 SNPs were included. Concerning the association between the ULK gene family and the age of first onset of the TBAD, only ULK4 was found to be significant according to SKAT analysis (q-FDR = 0.0088). From 2-sample MR, the high level of ULK4 gene expression was related to a later age of first onset of TBAD (β = 4.58, p = 0.0214).

Conclusion: This is the first study of the ULK gene family in TBAD, regarding the association with the first onset age. We demonstrated that the ULK4 gene is associated with the time of onset of TBAD based on both the SKAT and 2-sample MR analyses.

Cardiovascular Outcomes in Aortopathy: GenTAC Registry of Genetically Triggered Aortic Aneurysms and Related Conditions

BACKGROUND

The GenTAC (Genetically Triggered Thoracic Aortic Aneurysm and Cardiovascular Conditions) Registry enrolled patients with genetic aortopathies between 2007 and 2016.

OBJECTIVES

The purpose of this study was to compare age distribution and probability of elective surgery for proximal aortic aneurysm, any dissection surgery, and cardiovascular mortality among aortopathy etiologies.

METHODS

The GenTAC study had a retrospective/prospective design. Participants with bicuspid aortic valve (BAV) with aneurysm (n = 879), Marfan syndrome (MFS) (n = 861), nonsyndromic heritable thoracic aortic disease (nsHTAD) (n = 378), Turner syndrome (TS) (n = 298), vascular Ehlers-Danlos syndrome (vEDS) (n = 149), and Loeys-Dietz syndrome (LDS) (n = 121) were analyzed.

RESULTS

The 25% probability of elective proximal aortic aneurysm surgery was 30 years for LDS (95% CI: 18-37 years), followed by MFS (34 years; 95% CI: 32-36 years), nsHTAD (52 years; 95% CI: 48-56 years), and BAV (55 years; 95% CI: 53-58 years). Any dissection surgery 25% probability was highest in LDS (38 years; 95% CI: 33-53 years) followed by MFS (51 years; 95% CI: 46-57 years) and nsHTAD (54 years; 95% CI: 51-61 years). BAV experienced the largest relative frequency of elective surgery to any dissection surgery (254/33 = 7.7), compared with MFS (273/112 = 2.4), LDS (35/16 = 2.2), or nsHTAD (82/76 = 1.1). With MFS as the reference population, risk of any dissection surgery or cardiovascular mortality was lowest in BAV patients (HR: 0.13; 95% CI: 0.08-0.18; HR: 0.13; 95%: CI: 0.06-0.27, respectively). The greatest risk of mortality was seen in patients with vEDS.

CONCLUSIONS

Marfan and LDS cohorts demonstrate age and event profiles congruent with the current understanding of syndromic aortopathies. BAV events weigh toward elective replacement with relatively few dissection surgeries. Nonsyndromic HTAD patients experience near equal probability of dissection vs prophylactic surgery, possibly because of failure of early diagnosis.

Expanding ACTA2 genotypes with corresponding phenotypes overlapping with smooth muscle dysfunction syndrome

Pathogenic variants in ACTA2, encoding smooth muscle α-actin, predispose to thoracic aortic aneurysms and dissections. ACTA2 variants altering arginine 179 predispose to a more severe, multisystemic disease termed smooth muscle dysfunction syndrome (SMDS; OMIM 613834). Vascular complications of SMDS include patent ductus arteriosus (PDA) or aortopulmonary window, early-onset thoracic aortic disease (TAD), moyamoya-like cerebrovascular disease, and primary pulmonary hypertension. Patients also have dysfunction of other smooth muscle-dependent systems, including congenital mydriasis, hypotonic bladder, and gut hypoperistalsis. Here, we describe five patients with novel heterozygous ACTA2 missense variants, p.Arg179Gly, p.Met46Arg, p.Thr204Ile, p.Arg39Cys, and p.Ile66Asn, who have clinical complications that align or overlap with SMDS. Patients with the ACTA2 p.Arg179Gly and p.Thr204Ile variants display classic features of SMDS. The patient with the ACTA2 p.Met46Arg variant exhibits exclusively vascular complications of SMDS, including early-onset TAD, PDA, and moyamoya-like cerebrovascular disease. The patient with the ACTA2 p.Ile66Asn variant has an unusual vascular complication, a large fusiform internal carotid artery aneurysm. The patient with the ACTA2 p.Arg39Cys variant has pulmonary, gastrointestinal, and genitourinary complications of SMDS but no vascular manifestations. Identifying pathogenic ACTA2 variants associated with features of SMDS is critical for aggressive surveillance and management of vascular and nonvascular complications and delineating the molecular pathogenesis of SMDS.

Imaging and Surveillance of Chronic Aortic Dissection: A Scientific Statement From the American Heart Association

All patients surviving an acute aortic dissection require continued lifelong surveillance of their diseased aorta. Late complications, driven predominantly by chronic false lumen degeneration and aneurysm formation, often require surgical, endovascular, or hybrid interventions to treat or prevent aortic rupture. Imaging plays a central role in the medical decision-making of patients with chronic aortic dissection. Accurate aortic diameter measurements and rigorous, systematic documentation of diameter changes over time with different imaging equipment and modalities pose a range of practical challenges in these complex patients. Currently, no guidelines or recommendations for imaging surveillance in patients with chronic aortic dissection exist. In this document, we present state-of-the-art imaging and measurement techniques for patients with chronic aortic dissection and clarify the need for standardized measurements and reporting for lifelong surveillance. We also examine the emerging role of imaging and computer simulations to predict aortic false lumen degeneration, remodeling, and biomechanical failure from morphological and hemodynamic features. These insights may improve risk stratification, individualize contemporary treatment options, and potentially aid in the conception of novel treatment strategies in the future.

Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant, age-related but highly penetrant condition with substantial intrafamilial and interfamilial variability. MFS is caused by pathogenetic variants in FBN1, which encodes fibrillin-1, a major structural component of the extracellular matrix that provides support to connective tissues, particularly in arteries, the pericondrium and structures in the eye. Up to 25% of individuals with MFS have de novo variants. The most prominent manifestations of MFS are asymptomatic aortic root aneurysms, aortic dissections, dislocation of the ocular lens (ectopia lentis) and skeletal abnormalities that are characterized by overgrowth of the long bones. MFS is diagnosed based on the Ghent II nosology; genetic testing confirming the presence of a FBN1 pathogenetic variant is not always required for diagnosis but can help distinguish MFS from other heritable thoracic aortic disease syndromes that can present with skeletal features similar to those in MFS. Untreated aortic root aneurysms can progress to life-threatening acute aortic dissections. Management of MFS requires medical therapy to slow the rate of growth of aneurysms and decrease the risk of dissection. Routine surveillance with imaging techniques such as transthoracic echocardiography, CT or MRI is necessary to monitor aneurysm growth and determine when to perform prophylactic repair surgery to prevent an acute aortic dissection.

Genetic aortic disease epidemiology, management principles, and disparities in care

Patients with syndromic and nonsyndromic heritable aortopathies (also known as genetic aortic disease) are a heterogeneous group of patients who present at younger ages with more rapid growth of aortic aneurysms and/or increased frequency of dissections compared with patients with atherosclerotic aortopathies. In this review, we describe the etiology, epidemiology, and appropriate care delivery for these conditions at each stage of management. Within each section, we discuss sex, gender, and race differences and highlight disparities in care and knowledge. We then discuss the role of the vascular team throughout the cycle of care and the evolving inclusion of patient input in research. This understanding is essential to the creation of effective health care policies that support equitable, appropriate, and patient-centered clinical practices.

Characterization of syndromic, nonsyndromic familial, and sporadic type B aortic dissection

OBJECTIVE

Type B aortic dissection (TBAD) is commonly thought of as a sporadic event. However, an increasing body of data has suggested that genetic factors can influence TBAD. Our aim was to determine the prevalence of heritable TBAD, defined as either syndromic TBAD or nonsyndromic familial TBAD and to detail the natural history and long-term clinical outcomes compared with patients with "sporadic" TBAD without an identified syndrome or family history.

METHODS

The clinical records of 389 patients with TBAD who had presented to a single health care system from 1995 to 2017 were reviewed. A family history was obtained by interview and/or medical record review. Syndromic TBAD was defined as TBAD in patients with Marfan, Loeys-Dietz, or vascular Ehlers-Danlos syndrome. Nonsyndromic familial TBAD was defined as a family history of aortic or arterial aneurysm or dissection and/or sudden death in a first- or second-degree relative in the absence of a known syndrome. Patients with syndromic and nonsyndromic familial TBAD were compared with patients with sporadic TBAD in terms of the comorbid conditions, aortic repair, and mortality.

RESULTS

Of 389 patients (71.2% male) with TBAD, the etiology of TBAD was heritable in 27.9% (9.6% syndromic; 18.3% nonsyndromic familial TBAD) and 72.1% sporadic of the cases. Patients with syndromic and nonsyndromic familial TBAD had been more frequently referred in the chronic phase than were the patients with sporadic TBAD (35.5% vs 44.1% vs 25.8%; P = .014) and had presented at a younger age (40.6 ± 10.9 years vs 55.2 ± 11.3 years vs 62 ± 12.9 years; P < .001) and with lower blood pressure at acute TBAD (systolic, 159.2 ± 21 mm Hg vs 178.9 ± 39.3 mm Hg vs 186.1 ± 38.4, P = .01; diastolic, 84.3 ± 17.3 mm Hg vs 91.4 ± 24.1 mm Hg vs 101.6 ± 22.3 mm Hg, P = .001). Among patients with acute TBAD surviving to discharge from the initial hospitalization, thoracic endovascular aortic repair (TEVAR) had been performed in 115 patients, with no significant differences in TEVAR usage in the three groups. However, those with syndromic and nonsyndromic familial TBAD had had a greater incidence of retrograde aortic dissection after TEVAR (33.3% vs 15% vs 3%; P = .006). They had also required a greater number of arch repairs (30% vs 10.5% vs 3.6%; P < .001) and had died at a younger age (47.7 ± 13.1 years vs 65.7 ± 13.7 years vs 72.8 ± 12.7 years; P < .001). Aortic-related mortality was more common among patients with syndromic TBAD (36.7% vs 12.3% vs 17.6%; P = .016).

CONCLUSIONS

In our single-institutional experience, heritable TBAD accounted for one in four patients with TBAD. Nonsyndromic familial TBAD was twice as common as syndromic TBAD and appeared to share many clinical features. Identifying these patients early in their disease course and personalizing their care might improve their survival.

Cause-specific mortality of type B aortic dissection and assessment of competing risks of mortality

OBJECTIVE

Natural history studies of type B aortic dissection (TBAD) commonly report all-cause mortality. Our aim was to determine cause-specific mortality in TBAD and to evaluate the clinical characteristics associated with aorta-related and nonaorta-related mortality.

METHODS

Clinical and administrative records were reviewed for patients with acute TBAD between 1995 and 2017. Demographics, comorbidities, presentation, and initial imaging findings were abstracted. Cause of death was ascertained through a multimodality approach using electronic health records, obituaries, social media, Social Security Death Index, and state mortality records. Causes of death were classified as aorta related, nonaorta related, or unknown. A Fine-Gray multivariate competing risk regression model for subdistribution hazard ratio was employed to analyze the association of clinical characteristics with aorta-related and nonaorta-related mortality.

RESULTS

A total of 275 individuals met inclusion criteria (61.1 ± 13.7 years, 70.9% male, 68% white). Mean survival after discharge was 6.3 ± 4.7 years. Completeness of follow-up Clark C index was 0.87. All-cause mortality was 50.2% (n = 138; mean age, 70.1 ± 14.6 years) including an in-hospital mortality of 8.4%. Cause-specific mortality was aorta related, nonaorta related, and unknown in 51%, 43%, and 6%, respectively. Compared with patients with nonaorta-related mortality, patients with aorta-related mortality were younger at acute TBAD (69.5 ± 11.2 years vs 61.6 ± 15.5 years; P = .001), underwent more descending thoracic aortic repairs (19.4% vs 45.8%; P = .002), and had a shorter survival duration (5.7 ± 3.9 vs 3.4 ± 4.5 years; P = .002). There was clear variation in cause of death by each decade of life, with higher aorta-related mortality among those younger than 50 years and older than 70 years and a stepwise increase in nonaorta-related mortality with each increasing decade (P < .001). All-cause mortality at 1 year, 3 years, and 10 years was 15%, 24%, and 57%, respectively. After accounting for competing risks, the cumulative incidence of aorta-related mortality at 1 year, 3 years, and 10 years was 8.9%, 16.5%, and 27.2%, respectively, and that of nonaorta-related mortality was 2.7%, 7.2%, and 29%, respectively. A maximum descending thoracic aortic diameter >4 cm was associated with an increase in hazard of aorta-related mortality by 84% (subdistribution hazard ratio, 1.84; 95% confidence interval, 1.03-3.28) on multivariate competing risk regression analysis.

CONCLUSIONS

TBAD is associated with high 10-year mortality. Those at risk for aorta-related mortality have a clinical phenotype different from that of individuals at risk for nonaorta-related mortality. This information is important for building risk prediction models that account for competing mortality risks and to direct optimal and individualized surgical and medical management of TBAD.