A 58-year-old man with a 50-pack-year smoking history and COPD presents with a 6-week history of a pulsatile abdominal mass and progressive back pain. On examination, a tender, expansile mass is palpated above the umbilicus. CT angiography reveals a 5.5 cm infrarenal abdominal aortic aneurysm (AAA) with no evidence of rupture. The patient is haemodynamically stable. Which of the following is the most appropriate management?