Effect of Two Years of Doxycycline Treatment on Infrarenal Aortic Neck Diameter.

Objective: Endovascular aneurysm repair (EVAR) is a widely used option for patients with suitable vascular anatomy who have a large infrarenal abdominal aortic aneurysm (AAA). Neck diameter is the primary anatomical determinant of EVAR eligibility and device durability. Doxycycline has been proposed to stabilise the proximal neck after EVAR. This study explored doxycycline mediated aortic neck stabilisation in patients with small AAA, monitored by computed tomography over two years. Methods: This was a multicentre prospective randomised clinical trial. Subjects from the Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA Results: One hundred and ninety-seven subjects (171 male, 26 female) were included in the analysis. All patients, regardless of treatment arm, demonstrated larger neck diameter caudally, a slight increase in diameter at all anatomical levels over time, and greater growth caudally. There was no statistically significant difference in infrarenal neck diameter between treatment arms at any anatomical level at any time point, nor mean change in neck diameter over two years. Conclusion: Doxycycline does not demonstrate infrarenal aortic neck growth stabilisation in small AAA followed for two years by thin cut CT imaging using a standardised acquisition protocol and cannot be recommended for mitigation of growth of the aortic neck in patients with untreated small abdominal aortic aneurysms.