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Wide chest aorta found by chance

The aorta is the main artery leaving the heart. A chest CT, MRI or echo done for another reason may report that the part in the chest is wider than usual, called thoracic aortic dilation or, when larger, an aneurysm. (ACC/AHA 2022)(MedlinePlus) This page covers how it is measured, which repeat scans are usual and when relatives are checked, not surgery, medicines or treatment.

The main guidance

  • ACC/AHA aortic disease guideline (US, 2022): how to measure and report the aorta, when to repeat scans and when to check relatives or test for a genetic cause. (ACC/AHA 2022)
  • ESC peripheral arterial and aortic diseases guideline (Europe, 2024): summarized here through an open-access review; it covers the first scans after diagnosis and inherited aortic disease. (ESC 2024 review)

Who it applies to

Adults whose chest scan, done for another reason, mentions a wide or dilated thoracic aorta. In one US study of chest CT scans in people aged 55 to 80, 2.7% had a wide ascending aorta (4 to 5 cm) reported by chance. (Benedetti 2015) A wide aorta in the belly is covered on AAA screening results. If you have a bicuspid aortic valve or Marfan syndrome, see screenings if you have a bicuspid aortic valve or screenings for people with Marfan syndrome.

How size is measured and described

Ascending aorta size terms in the ACC/AHA 2022 guideline (simplified)
TermDiameterNotes from the guideline
Dilated4.0 cm or moreAbout 2.6% of adults in a large US population study
Aneurysm4.5 cm or moreAbout 0.2% in the same study
  • The guideline says it is reasonable for a report to give the size indexed to body size: the aortic size index (diameter divided by body surface area) or the aortic height index (diameter divided by height). Normal size varies with age, sex, height and body size. (ACC/AHA 2022)
  • The guideline divides the aorta in the chest into the root (where it leaves the heart), the ascending aorta, the arch and the descending aorta, and a report may say which part is wide. (ACC/AHA 2022)
  • Measurements can differ between kinds of scan, and even between scans with and without contrast dye, so growth of 1 to 2 mm a year is hard to show reliably. (ACC/AHA 2022)

Which repeat scan is usual, and how often

  • At diagnosis: the ACC/AHA guideline recommends an echocardiogram (TTE) to look at the aortic valve and the aorta, and says a CT or MRI is reasonable to measure the whole thoracic aorta. (ACC/AHA 2022) The ESC review describes the same echo of the valve, followed by a cardiac MRI or cardiac CT to record the starting size. (ESC 2024 review)
  • First repeat: a repeat scan (echo, CT or MRI, depending on which shows your aorta best) in 6 to 12 months is reasonable to see whether it is growing. (ACC/AHA 2022)
  • If it is stable: repeat scans every 6 to 24 months, with the interval depending on the size. (ACC/AHA 2022)

When relatives are checked or a genetic cause is looked for

  • For an aneurysm of the aortic root or ascending aorta, the ACC/AHA guideline recommends a family history over several generations, covering aortic disease, unexplained sudden deaths and other aneurysms. (ACC/AHA 2022) The ESC review says at least three generations. (ESC 2024 review)
  • Genetic testing is recommended when there are risk factors for an inherited cause: features of Marfan, Loeys-Dietz or vascular Ehlers-Danlos syndrome, onset before age 60, a family history of aortic disease or other aneurysms in a first- or second-degree relative, or an unexplained sudden death at a fairly young age in such a relative. (ACC/AHA 2022)
  • Imaging of first-degree relatives is recommended, including when no genetic cause is found. (ACC/AHA 2022)

What changes the plan

  • Growth: the ACC/AHA guideline counts growth of 0.5 cm or more in 1 year, or 0.3 cm or more a year for 2 years in a row, as rapid; for inherited aortic disease or a bicuspid valve the mark is 0.3 cm in 1 year. (ACC/AHA 2022) The ESC review lists growth of 3 mm a year or more in the ascending aorta as a risk factor. (ESC 2024 review)
  • Usual growth is slow: the guideline gives average growth for a sporadic ascending aorta of about 0.01 to 0.03 cm a year. (ACC/AHA 2022) In the US CT study, 3.7% of people with a later scan showed growth over an average of 3.4 years. (Benedetti 2015)
  • Symptoms: MedlinePlus lists chest or back discomfort as a reason to contact your provider (below). (MedlinePlus)

If the same scan showed calcium in the heart arteries, see heart artery calcium found by chance.

MedlinePlus, when to contact a medical professional: (MedlinePlus)

Contact your health care provider if you have:

  • A family history of connective tissue disorders (such as Marfan or Ehlers-Danlos syndrome)
  • Chest or back discomfort

Routine age-based screening

A finding on a scan does not replace the routine screenings for your age; see screenings by age and gender.

Where they differ:

  • Which scan first. The ACC/AHA guideline recommends an echo and says a CT or MRI is reasonable. (ACC/AHA 2022) The ESC review says the starting size should be recorded with a cardiac MRI or cardiac CT after the echo. (ESC 2024 review)
  • Family history. The ACC/AHA guideline asks for a multigenerational history; the ESC review names at least three generations and counselling at a specialist center. (ACC/AHA 2022)(ESC 2024 review)
  • How often to scan. The ACC/AHA guideline gives a range of 6 to 24 months once stable. (ACC/AHA 2022) The authors of the US CT study, where few aortas grew, suggest yearly scans for a 4 to 5 cm ascending aorta could be spaced further apart or targeted better. (Benedetti 2015)

Your doctor decides what your result means for you.

Questions people ask

What size counts as a wide aorta?

The ACC/AHA 2022 guideline calls an ascending aorta of 4.0 cm or more dilated and 4.5 cm or more an aneurysm. It also says normal size varies with age, sex, height and body size. (ACC/AHA 2022)

Will I need another scan?

Usually. The ACC/AHA guideline says a repeat scan in 6 to 12 months is reasonable to see if it is growing, then every 6 to 24 months depending on the size if it is stable. Your doctor decides. (ACC/AHA 2022)

Why was I offered an echo?

The ACC/AHA and ESC guidance both recommend an echocardiogram when a wide chest aorta is found, partly to look at the aortic valve, for example whether it is bicuspid. (ACC/AHA 2022) (ESC 2024 review)

Should my family be checked?

The ACC/AHA guideline recommends imaging of first-degree relatives of people with an aneurysm of the aortic root or ascending aorta. Your doctor can tell you whether that applies to your finding. (ACC/AHA 2022)

How often does it grow?

Often slowly. In one study of chest CT scans in people aged 55 to 80, only 3.7% of those with a wide ascending aorta and a later scan showed growth over an average of 3.4 years. (Benedetti 2015)

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