Randomized Clinical Trials of Endovascular Repair Versus Surveillance for Treatment of Small Abdominal Aortic Aneurysms

Abstract

The Aneurysm Detection and Management (ADAM) trial and the United Kingdom Small Aneurysm Trial (UKSAT) demonstrated that early open surgical repair of small (<5.5 cm in diameter) abdominal aortic aneurysms (AAAs) conveyed no benefits compared with surveillance. In 2 randomized controlled trials (RTCs), operative mortality rates were significantly lower with endovascular aneurysm repair (EVAR) than with open surgery for treatment of large AAAs. Retrospective analyses of EVAR databases suggested that EVAR outcomes are directly related to aneurysm size and are better for smaller AAAs. It has thus seemed logical that a less invasive treatment strategy might be beneficial in treating patients with small AAAs. Two new RCTs have been initiated to evaluate early EVAR versus surveillance in patients with small AAAs. The European-based 17-site CAESAR (Comparison of surveillance vs Aortic Endografting for Small Aneurysm Repair) trial had enrolled 740 patients with small AAAs (4.1-5.4 cm) for surveillance or EVAR with the Zenith stent-graft. The primary endpoint of CAESAR is all-cause mortality at 54 months. The 70-site PIVOTAL (Positive Impact of endoVascular Options for Treating Aneurysm earLy) trial in the United States is enrolling up to 1025 patients with small AAAs (4-5 cm) for surveillance or EVAR with the AneuRx or Talent stent-grafts. The primary endpoints of PIVOTAL are aneurysm rupture and AAA-related deaths at up to 36 months after randomization. CAESAR and PIVOTAL should provide objective evidence to guide the use of EVAR for small AAAs.