Background: Early identification of patients at risk for thoracic aortic aneurysm (TAA) has the potential of improving prognosis. So far, however, "normal" aortic dimensions are not well defined, rendering identification of patients with enlarged aortas difficult. In the present study we aimed to (1) establish age- and gender-specific distribution of thoracic aortic diameters and (2) to determine the prevalence of asymptomatic TAA in a population-based European cohort.
Methods: Diameters of ascending thoracic aorta (ATA) and descending thoracic aorta (DTA) were measured from electron beam computed tomography (EBCT) scans of 4129 participants aged 45 to 75 years from the Heinz Nixdorf Recall study. Age- and gender-specific percentiles were calculated for body-surface adjusted aortic diameters. Multivariable linear regression was used to evaluate the association between aortic diameters and cardiovascular risk factors including age, gender and body-surface area (BSA).
Results: Aortic diameters were generally greater in the ATA than in the DTA, and were greater in men than in women (ATA: 3.71 ± 0.4 cm vs. 3.45 ± 0.4 cm, p<0.0001; DTA: 2.82 ± 0.3 cm vs. 2.54 ± 0.3 cm, p<0.0001). Age, male gender, blood pressure and body-surface area were independently associated with aortic diameters in both ATA and DTA. Based on our measurements age- and gender-specific percentiles for indexed ATA and DTA diameters were computed. Aneurysms ≥ 5 cm were found in 12 (0.34%) out of the total of 4129 subjects.
Conclusion: Since BSA was independently associated with increasing aortic diameters, correction of aortic diameters for BSA may be more helpful in order to reliably identify patients at risk for aneurysm formation. Based on the normal distribution of body-surface adjusted thoracic aortic diameters displayed in age- and gender-specific percentiles we suggest a cut-off point for aneurismal aortic diameter at the 95th percentile.
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