The Journal of Thoracic and Cardiovascular Surgery
J Thorac Cardiovasc Surg 2019. Epub 2019.
Objectives: Elucidating critical aortic diameters at which natural complications occur (rupture, dissection, death) is paramount to guide timely surgical intervention. Natural history knowledge for descending thoracic or thoracoabdominal aortic aneurysms (DTTAA) is sparse. Our small early studies recommended repairing DTTAAs before a critical diameter of 7.0cm. Here we focus exclusively on a large number of DTTAAs followed over time, enabling more detailed analysis with greater granularity across aortic sizes.
Methods: Aortic diameters and long-term complications of 907 patients with DTTAA were reviewed. Growth rates (instrumental variables approach), yearly complication rates, 5-year event-free survival (Kaplan-Meier), and risk of complications as a function of aortic-height index (AHI) (aortic diameter [cm]/height [m]) (Competing-risks regression) were calculated.
Results: Estimated mean growth rate of DTTAAs was 0.19 cm/year, increasing with increasing aortic size. Median size at acute type B dissection was 4.1cm. 80% of dissections occurred below 5cm, whereas 93% of ruptures occurred above 5cm. DTTAA diameter ≥ 6cm was associated with a 19% yearly rate of rupture, dissection, or death. 5-year complication free survival progressively decreased with increasing AHI. Hazard of complications showed 6-fold increase at AHI ≥ 4.2 compared to AHI 3.0-3.5 (P < .05). Probability of fatal complications (aortic rupture or death) increased sharply at 2 hinge points: 6.0 and 6.5 cm.
Conclusion: Acute type B dissections occur frequently at small aortic sizes; thus, prophylactic size-based surgery may not afford a means for dissection protection. However, fatal complications increase dramatically at 6.0 cm, suggesting that preemptive intervention before that criterion can save lives.