Emergency Department Referral for Rapidly Growing Infrarenal Aneurysm

Rationale for Emergency Department Admission

A patient with a rapidly growing infrarenal abdominal aortic aneurysm (AAA) should be admitted to the emergency department immediately for ICU monitoring, blood pressure control, and urgent surgical evaluation within 24-48 hours, as rapid aneurysm growth (≥7 mm in 6 months or >10 mm in 12 months) represents a high-risk feature for impending rupture 1, 2
The American College of Cardiology recommends urgent intervention rather than routine surveillance for patients with rapid aneurysm growth, due to the elevated rupture risk 2

Symptomatic presentation, such as pain in the back, abdomen, or flank attributable to the AAA, indicates impending rupture and requires immediate ICU admission for arterial blood pressure monitoring, tight BP control, and AAA repair ideally within 24-48 hours 1, 2
Rapid expansion rate, exceeding the threshold of 7 mm in 6 months or 10 mm in 12 months, significantly increases rupture risk and necessitates urgent intervention 1, 2

The American College of Cardiology recommends ICU admission for continuous arterial blood pressure monitoring and tight BP control to prevent rupture, with a blood pressure target of normotensive blood pressure, reducing SBP by no more than 25% within the first hour, then if stable to 160/100 mm Hg within 2-6 hours 1, 2, 3, 4
Urgent imaging, such as CT angiography, should be obtained to characterize aneurysm anatomy, confirm rapid growth, and plan for repair 5

Repair should be performed within 24-48 hours to reduce the risk of free rupture while allowing time for medical optimization and cardiorespiratory assessment 1, 2

Untreated symptomatic or rapidly expanding AAAs have a 1-year death rate >79% with median survival of only 10.4 months, according to the American College of Cardiology 3
Observational studies demonstrate higher mortality in patients treated for symptomatic aneurysms compared to elective repair, emphasizing the need for urgent rather than delayed intervention 1, 2

Saccular morphology aneurysms are more likely to become symptomatic and rupture at smaller diameters than fusiform AAAs, with 25% of acute presentations occurring at diameters <5.5 cm 1, 2
Female sex is associated with higher rupture rates at smaller diameters (mean rupture diameter 5.0 cm vs 6.0 cm in men), and aneurysm size index (ASI) may be more predictive than absolute diameter 1, 2
The American College of Cardiology recommends not delaying emergency evaluation based on aneurysm size alone, as rapid growth rate is an independent high-risk feature that supersedes size thresholds for elective repair 1, 2