Exploring the Acceptable Delay for Elective Treatment of Patients With an Abdominal Aortic Aneurysm: A Reflection During a Pandemic and an Exploratory Analysis

Abstract

Introduction: This study sought to determine the rupture risk of asymptomatic abdominal aortic aneurysms (AAAs) undergoing interventions as a function of time to establish a maximal acceptable surgical delay.

Methods: A literature review was performed from inception to August 30, 2021, to assess the risk of rupture of aneurysms over time. The analysis was limited to men with asymptomatic AAAs. The data on AAA rupture risk according to diameter and follow-up time were extracted. The acceptable mortality risk for AAA patients as a function of surgical delay was further evaluated. This acceptable mortality risk was based on the acceptable risk of cardiovascular death associated with the accepted delays of coronary revascularization in coronary artery disease populations. Data on estimated surgical delays and risks were extracted using a free web-based software (WebPlotDigitizer) and plotted using Microsoft Excel.

Results: Our study identified minimal evidence as it pertains to AAA rupture risk as a function of surgical delay. The data on rupture risk of AAAs according to diameter and time were extracted from a single review and a single meta-analysis (Figure 1). The acceptable delays of semiurgent and nonurgent invasive treatment for coronary artery disease found in literature are 6 and 12 wks respectively. These acceptable delays are associated with an estimated acceptable cardiovascular mortality risk threshold of 0.47% at 6 and 12 wks. Using this threshold of estimated maximum acceptable risk and the data on the natural history of AAAs found in our review, we found that the acceptable surgical delays for AAAs would be estimated at 13-27 ds for AAAs ≥ 7 cm, 20-42 ds for 6-6.9 cm, and 32-49 ds for 5.5-5.9 cm (Figure 1).

Conclusions: This study identified estimated surgical delays for patients with AAAs based on the acceptable maximum risk. These estimations may be used cautiously to triage patients with asymptomatic AAAs, particularly in the setting of triaging patients during local and global crises.

Keywords: Acceptable risk; Aortic abdominal aneurysm; Rupture risk; Surgical delay; Vascular surgery.