A 69-year-old man is evaluated during a routine examination. He is asymptomatic. Medical history is significant for hypertension. He has a 50-pack-year smoking history but quit smoking 7 years ago. Medications are aspirin, lisinopril, and amlodipine.
On physical examination, vital signs are normal. A bruit is heard over the abdomen, and a pulsatile mass is present in the epigastrium. The remainder of the examination is unremarkable.
A Duplex ultrasound of the abdomen shows an abdominal aortic aneurysm with transverse diameter of 6.2 cm.
Which of the following is the most appropriate next step in management?
A. CT angiography of the abdominal aorta and iliac vessels
B. Endovascular repair
C. Open surgical repair
D. Switch amlodipine to metoprolol
MKSAP Answer and Critique
The correct answer is A. CT angiography of the abdominal aorta and iliac vessels. This content is available to MKSAP 18 subscribers as Question 16 in the Cardiovascular Medicine section. More information about MKSAP is available online.
The most appropriate next step in management of this patient with an abdominal aortic aneurysm (AAA) is CT angiography of the abdominal aorta and iliac vessels to plan for aortic repair. The strongest risk factor for rupture of an AAA is maximal aortic diameter; this measurement is the dominant indication for repair. Aortic repair should be performed in suitable patients with an AAA diameter of 5.5 cm or larger, in patients with rapid expansion in AAA size (>0.5 cm/year), and in patients presenting with symptoms resulting from AAA (abdominal or back pain/tenderness). In patients with an indication for aortic repair, the choice is between open surgical repair and endovascular aneurysm repair (EVAR). Open surgical repair involves abdominal flank incision and opening the aneurysm sac with interposition of a synthetic graft. EVAR is a less invasive method involving intraluminal introduction of a covered stent through the aneurysm sac, with the stent acting as a sleeve. The choice of procedure is driven by several considerations, including the patient's operative risk, expected lifespan, and ability to adhere to the monitoring requirements of EVAR; the location of the AAA; and involvement of the renal and mesenteric arteries. Suprarenal and juxtarenal aneurysms most often necessitate open surgical repair, whereas infrarenal aneurysms may be treated with open surgery or EVAR. In this patient, CT angiography or magnetic resonance angiography should be performed to determine the location and extent of the AAA. Abdominal duplex ultrasonography is insufficient to determine AAA location. In addition, CT measurements exceed ultrasound measurements in 95% of cases.
Although controlling risk factors for cardiovascular disease is essential in patients with AAA, there is little compelling evidence for treating hypertension in these patients with a specific agent, including β-blockers, to prevent aneurysm expansion. Because this patient's blood pressure is well controlled, no change in antihypertensive therapy is indicated. Importantly, an AAA with a diameter of 6.2 cm has a 10% to 20% annual risk for rupture, and definitive surgical therapy is indicated.
- In patients with an indication for abdominal aortic aneurysm repair, the choice between open surgical repair and endovascular aneurysm repair is driven in part by the location of the aneurysm and involvement of the renal and mesenteric arteries.