Patients with nonsyndromic thoracic aortic aneurysm and dissection (nsTAAD) may have systemic arterial involvement, but the distribution and clinical correlates of extrathoracic disease remain poorly defined. We conducted a retrospective cohort study of adults with nsTAAD at Mayo Clinic (2018–2024). Trained reviewers manually confirmed thoracic aortic dilation and all extrathoracic vascular lesions; syndromic, congenital, and fibromuscular dysplasia-related cases were excluded. Cross-sectional imaging availability was abstracted for the head or neck, chest, and abdomen or pelvis. Detection frequencies of nonthoracic aneurysm (nTA-A) were calculated among patients imaged in ≥1 extrathoracic territory, while nonaortic dissection (nTA-D) frequencies used the full cohort denominator. Group differences were assessed using Chi-square or t Tests, and logistic regression identified predictors of nTA-A. Among 3,989 patients (28.6% female), 82.0% had CT or MRI of ≥1 extrathoracic territory. nTA-A was detected in 443/3,270 (13.5%) and increased with age (7.4% at 18–30 years, 8.4% at 31 to 50 years, 18.3% at ≥51 years; p <0.001), with the greatest detection burden in the abdomen or pelvis followed by the head/neck. nTA-D occurred in 136/3,989 (3.4%) and also rose with age (0.7%, 2.2%, 4.9%; p <0.001). Hypertension and hyperlipidemia were independently associated with nTA-A (p ≤0.05). Patients with nTA-A or nTA-D had higher rates of heart failure, myocardial infarction, stroke, and mortality (all p ≤0.01). In conclusion, extrathoracic aneurysms and dissections are common in nsTAAD and increase with age, supporting careful clinical assessment with vigilant symptom monitoring and risk factor optimization, and providing a foundation for future studies to determine when broader vascular evaluation improves longitudinal risk stratification and outcomes.
Heritable thoracic aortic disease comprises a spectrum of syndromic and nonsyndromic conditions unified by arterial wall vulnerability but distinguished by their genetic and clinical trajectories. ,,,, While routine surveillance has traditionally centered on the thoracic aorta, growing evidence suggests that aortic disease in many patients reflects a broader vasculopathy that can involve extrathoracic arterial territories. , This diffuse arterial phenotype is well recognized in syndromic connective-tissue disorders such as Marfan, Loeys–Dietz, and vascular Ehlers–Danlos syndromes, yet the frequency, distribution, and clinical context of extrathoracic involvement in nonsyndromic thoracic aortic aneurysm and dissection (nsTAAD) remain less certain. nsTAAD includes familial and apparently sporadic forms of heritable aortic disease, distinct from syndromic connective-tissue disorders and congenital aortic malformations, but emerging mechanistic data point to shared pathways that may extend risk beyond the thoracic aorta, including altered vascular smooth-muscle contractility, extracellular-matrix integrity, and inflammatory remodeling. ,,,,,, Despite this biologic rationale, clinical insight has been limited by variation in imaging practices and inconsistent approaches to reporting detection frequencies across vascular territories. ,, A clearer understanding of the burden and distribution of extrathoracic arterial disease in nsTAAD is needed to better contextualize systemic vascular risk and to guide future efforts in surveillance and risk stratification. Accordingly, this study characterizes the detection frequency and patterns of extrathoracic aneurysm and dissection in nsTAAD, providing data to inform future genotype-integrated and population-comparative research. ,,,,,,,
Methods
Study design and setting
We conducted a retrospective cohort study of adults aged ≥18 years evaluated for thoracic aortic aneurysm or dissection (TAAD) across Mayo Clinic sites in Rochester, Arizona, and Florida between 2018 and 2024. The Institutional Review Board approved the study with a waiver of informed consent because of its minimal risk, retrospective nature.
Cohort assembly and inclusion criteria
Patients were identified using International Classification of Diseases, Tenth Revision (ICD-10) codes consistent with TAAD. Each patient underwent a detailed manual chart review of clinical documentation and available imaging at Mayo Clinic, including echocardiography and cross-sectional imaging (CT or MRI) within the Enterprise Imaging Management System (EIMS), to confirm thoracic aortic dilation/dissection and to classify any extrathoracic vascular events. Imaging was restricted to those performed within the Mayo system. In most patients, thoracic aortic pathology was first evaluated by echocardiography, with EIMS used to review and standardize aortic measurements from available imaging, including body size adjustment and other relevant factors when reported within the imaging record. nsTAAD was defined as a TAAD occurring in the absence of syndromic connective-tissue disorders, fibromuscular dysplasia, or congenital heart disease associated with major arch anomalies. Both familial and apparently sporadic nsTAAD cases were included, recognizing that heritable predisposition is intrinsic to this disease spectrum.
Exclusion criteria
Patients were excluded if they had Marfan, Loeys–Dietz, or vascular Ehlers–Danlos syndromes; fibromuscular dysplasia; or congenital aortic malformations such as coarctation, transposition, or Tetralogy of Fallot. Individuals with bicuspid aortic valve, atrial septal defect, or patent foramen ovale were retained unless another exclusion criterion was met, as these features commonly coexist with otherwise nonsyndromic aortopathy.
Imaging ascertainment and denominator specification
Imaging exposure varied across patients, reflecting individualized clinical care rather than a standardized protocol. To minimize detection bias, all detection rate estimates were calculated using denominator-defined imaging exposure, representing the number of patients imaged in a given vascular territory (head/neck, chest, or abdomen/pelvis). For the overall nonthoracic aortic aneurysm (nTA-A) detection frequency, the denominator included patients who underwent imaging in at least one extrathoracic territory. For nonaortic dissection (nTA-D), which typically presents symptomatically, the entire cohort served as the denominator. When multiple studies were available, the most recent complete CT or MRI was analyzed to reflect each patient’s latest vascular status. Because a single patient could contribute multiple aneurysm or dissection detections across territories or within the same territory, analyses were performed at the event level rather than the unique-patient level. Lesions were recorded as present when explicitly documented in radiology or operative reports.
Event adjudication and definitions
All aneurysm and dissection events were manually confirmed by study investigators through direct review of imaging reports and relevant clinical documentation. Dissections were categorized as Type A aortic, Type B aortic, or nonaortic. Events clearly described as iatrogenic (e.g., procedural or access-related) were excluded from detection rate calculations unless imaging confirmed extension beyond the intervention site. Because patients could have more than one aneurysm or dissection, each confirmed lesion was treated as a separate detection for descriptive purposes.
Statistical analysis
Categorical variables were summarized as counts and percentages, and continuous variables as mean ± standard deviation or median [interquartile range], depending on distribution. Between-group comparisons used Chi-square or Fisher’s exact tests for categorical variables and t Tests or Wilcoxon rank-sum tests for continuous variables. To further evaluate clinical predictors of vascular involvement, multivariable logistic regression was performed for two outcomes: (1) any aortic or nonaortic dissection (entire cohort denominator) and (2) presence of nTA-A among patients with imaging available in at least one extrathoracic territory. Candidate covariates were selected in advance based on biological plausibility and previous vascular risk literature, including age >50 years, sex, hypertension, diabetes mellitus, hyperlipidemia, and abdominal aortic aneurysm. Odds ratios (ORs) with 95% confidence intervals (CIs) and p-values were estimated using heteroskedasticity-robust (HC3) standard errors under a binomial link. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC) and pseudo-R². All tests were two-sided, and p <0.05 was considered statistically significant. Analyses were performed in Python (version 3.11) using the statsmodels and scikit-learn libraries.
Results
Cohort characteristics and imaging exposure
Among 3,989 adults with nsTAAD, cross-sectional imaging was available in 1,351 for the head/neck, 2,748 for the chest, and 1,965 for the abdomen/pelvis; 3,270 (82.0%) underwent CT or MRI in ≥1 extrathoracic territory ( Table 1 ). Age-stratified denominators for those imaged in ≥1 extrathoracic territory were 285 (18–30 years), 1,256 (31–50 years), and 1,729 (≥ 51 years). These denominators formed the basis for all territory-specific detection estimates.
Table 1
Cross-sectional imaging exposure across vascular territories in patients with nonsyndromic thoracic aortic aneurysm and dissection
| Imaging | All ages (n) | 18–30 y (n) | 31–50 y (n) | 51 + y (n) |
|---|---|---|---|---|
| Imaging of head | 1351 | 125 | 435 | 691 |
| Imaging of chest | 2748 | 205 | 1067 | 1476 |
| Imaging of abdomen/pelvis | 1965 | 139 | 754 | 1072 |
| Imaging of at least one group* | 3270 | 285 | 1256 | 1729 |
CT = computed tomography; MRI = magnetic resonance imaging; y = years.
*Patients imaged in at least one extrathoracic vascular territory (head/neck, chest, or abdomen/pelvis).
Counts represent the number of patients with available cross-sectional imaging (CT or MRI) of each vascular territory. These values define the denominators used for all territory-specific detection rate estimates in subsequent tables. Imaging exposure varies by clinical indication rather than protocol.
Detection frequency and distribution of nTA-A
nTA-A were identified in 443 of 3,270 imaged patients (13.5%) with a clear age gradient (7.4% at 18–30 years, 8.4% at 31–50 years, and 18.3% at ≥51 years; p <0.001) ( Table 2 ). By territory, detection was 10.2% in the head/neck and 13.2% in the abdomen/pelvis; the abdominal aorta (6.0%) and iliac arteries (3.6%) were the most frequent sites. Thoracic nonaortic aneurysms were uncommon (1.4%), primarily coronary (0.6%) or pulmonary (0.8%).
Table 2
Detection frequency and anatomic distribution of nonthoracic aortic aneurysms by vascular territory and age group
| Aneurysm location | All patients (%) | 18–30 y (%) | 31–50 y (%) | 51 + y (%) | p-Value |
|---|---|---|---|---|---|
| Nonthoracic aorta | 443 (13.5%) | 21 (7.4%) | 105 (8.4%) | 317 (18.3%) | <0.001 |
| Head and neck | 138 (10.2%) | 9 (7.2%) | 38 (7.1%) | 91 (13.2%) | 0.001 |
| Cerebral | 56 (4.1%) | 5 (4.0%) | 16 (3.0%) | 35 (5.1%) | 0.195 |
| Carotid | 48 (3.6%) | 3 (2.4%) | 15 (2.8%) | 30 (4.3%) | 0.27 |
| Vertebral | 19 (1.4%) | 0 (0.0%) | 4 (0.7%) | 15 (2.2%) | 0.041 |
| Subclavian | 15 (1.1%) | 1 (0.8%) | 3 (0.6%) | 11 (1.6%) | 0.219 |
| Thoracic nonaortic | 39 (1.4%) | 2 (1.0%) | 13 (1.2%) | 24 (1.6%) | 0.592 |
| Coronary | 17 (0.6%) | 0 (0.0%) | 8 (0.7%) | 9 (0.6%) | 0.455 |
| Pulmonary | 22 (0.8%) | 2 (1.0%) | 5 (0.5%) | 15 (1.0%) | 0.298 |
| Abdomen and pelvis | 260 (13.2%) | 10 (7.2%) | 52 (6.9%) | 198 (18.5%) | <0.001 |
| Abdominal aorta | 118 (6.0%) | 8 (5.8%) | 29 (3.8%) | 81 (7.6%) | 0.004 |
| Celiac | 21 (1.1%) | 0 (0.0%) | 3 (0.4%) | 18 (1.7%) | 0.014 |
| Splenic | 12 (0.6%) | 0 (0.0%) | 5 (0.7%) | 7 (0.7%) | 0.631 |
| SMA/IMA | 8 (0.4%) | 0 (0.0%) | 0 (0.0%) | 8 (0.7%) | 0.035 |
| Hepatic | 4 (0.2%) | 0 (0.0%) | 2 (0.3%) | 2 (0.2%) | 0.803 |
| Renal | 21 (1.1%) | 0 (0.0%) | 1 (0.1%) | 20 (1.9%) | <0.001 |
| Iliac | 70 (3.6%) | 2 (1.4%) | 10 (1.3%) | 58 (5.4%) | <0.001 |
| Femoral | 6 (0.3%) | 0 (0.0%) | 2 (0.3%) | 4 (0.4%) | 0.731 |
| Upper extremity | 6 (0.2%) | 0 (0.0%) | 2 (0.2%) | 4 (0.2%) | 0.677 |
IMA = inferior mesenteric artery; SMA = superior mesenteric artery; y = years.
Percentages represent aneurysm detection frequencies within each vascular territory among patients with available cross-sectional imaging of that region (see Table 1 for imaging denominators). The numerator is the number of aneurysms identified in that territory, and the denominator is the number of patients imaged for that region. Because individual patients may have multiple aneurysms within or across territories, values represent detection frequency rather than unique-patient prevalence. “Nonthoracic Aorta” refers to the presence of ≥1 aneurysm in any extrathoracic vascular territory (head/neck, thoracic nonaortic, or abdomen/pelvis). p-Values reflect comparisons of detection rates across age groups using the Chi-square test.
Compared with those without nTA-A, patients with nTA-A were more often in the ≥ 51-year stratum (68.4% vs 51.2%; p <0.001) and had higher rates of hypertension (62.0% vs 49.4%; p <0.001), hyperlipidemia (42.0% vs 33.1%; p = 0.001), heart failure (33.4% vs 26.4%; p = 0.006), previous myocardial infarction (11.7% vs 6.3%; p <0.001), and previous stroke (19.3% vs 7.7%; p <0.001) ( Table 3 ). Sex distribution did not differ (p = 0.840). Race differed modestly (higher “All Others” in nTA-A: 12.6% vs 9.0%; p = 0.037).
Table 3
Demographic and clinical characteristics of patients with and without nonthoracic aortic aneurysm in the nonsyndromic TAAD cohort
| Variables | No nonthoracic aneurysm (n = 2957) n (%) | Nonthoracic aneurysm present (n = 326) n (%) | p-Value |
|---|---|---|---|
| Age groups (years) | <0.001 | ||
| 18–30 (n = 289) | 273 (9.2%) | 16 (4.9%) | |
| 31–50 (n = 1258) | 1171 (39.6%) | 87 (26.7%) | |
| 51 and greater (n = 1736) | 1513 (51.2%) | 223 (68.4%) | |
| Gender | 0.840 | ||
| Female | 850 (28.7%) | 92 (28.2%) | |
| Male | 2107 (71.3%) | 234 (71.8%) | |
| Race | 0.037 | ||
| Caucasian (n = 3601) | 2690 (91.0%) | 285 (87.4%) | |
| All Others (n = 390) | 267 (9.0%) | 41 (12.6%) | |
| Comorbidities | |||
| Obesity (BMI > 30) | 845 (28.6%) | 104 (31.9%) | 0.209 |
| Diabetes mellitus | 329 (11.1%) | 48 (14.7%) | 0.053 |
| Hypertension | 1460 (49.4%) | 202 (62.0%) | <0.001 |
| Migraines | 427 (14.4%) | 50 (15.3%) | 0.663 |
| Hyperlipidemia | 980 (33.1%) | 137 (42.0%) | 0.001 |
| Heart failure | 780 (26.4%) | 109 (33.4%) | 0.006 |
| Thyroid | 834 (28.2%) | 102 (31.3%) | 0.242 |
| Myocardial infarction | 185 (6.3%) | 38 (11.7%) | <0.001 |
| Stroke | 228 (7.7%) | 63 (19.3%) | <0.001 |
| Death* | 70 (2.4%) | 16 (4.9%) | 0.006 |
| Cardiac abnormalities | |||
| Bicuspid aortic valve | 937 (31.7%) | 69 (21.2%) | <0.001 |
| Ventricular septal defect | 45 (1.5%) | 7 (2.1%) | 0.391 |
| Atrial septal defect | 49 (1.7%) | 4 (1.2%) | 0.559 |
| Patent foramen ovale | 143 (4.8%) | 20 (6.1%) | 0.305 |
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