Risk of Rupture or Dissection in Descending Thoracic Aortic Aneurysm
Background—Current practice guidelines recommend surgical repair of large thoracic aortic aneurysms (TAA) to prevent fatal aortic dissection (AD) or rupture, but limited natural history data exist to support clinical criteria for timely intervention.
Methods and Results—Of 3,247 TAA patients registered in our institutional Thoracic Aortic Center Database, we identified and reviewed 257 non-syndromic patients (age 72.4±10.5 years, 143 females) with descending thoracic or thoracoabdominal aortic aneurysm (DTA/TAAA) without history of AD in whom surgical intervention was not undertaken. The primary endpoint was a composite of AD/rupture and sudden death. Baseline mean maximal aortic diameter was 52.4±10.8mm with 103 patients having diameters ≥ 55mm. During a median follow-up of 25.1 months (Quartile 1-3, 8.3-56.4 months), definite and possible aortic events occurred in 19 (7.4%) and 31 patients (12.1%), respectively. On multivariable analyses, maximal aortic diameter at baseline emerged as the only significant predictor of aortic events (HR=1.12; 95% CI, 1.08-1.15). Estimated rates of definite aortic events within 1 year were 5.5%, 7.2% and 9.3% at the aortic diameters of 50mm, 55mm and 60mm, respectively. Receiver operating characteristic for discriminating aortic events were higher for indexed aortic sizes referenced by body size (areas under curve [AUC]=0.832 to 0.889), but not significantly different to absolute maximal aortic diameter (AUC=0.805).
Conclusions—Aortic size was the principle factor related to aortic events in unrepaired DTA/TAAA. Although the risk of aortic events started to increase with a diameter above 5.0-5.5cm, it is uncertain if repair of TAAs in this range leads to overall benefit and the threshold for repair requires further evaluation.
- Received December 29, 2014.
- Revision received August 4, 2015.
- Accepted August 10, 2015.