Predictive factors of Splenic Artery Aneurysm Growth

The Natural History of Splenic Artery Aneurysms: Factors That Predict Aneurysm Growth

Clinical question

What factors predict splenic artery aneurysmal growth?

Take away point

A larger baseline splenic artery aneurysm, the presence of a mural thrombus and low amounts of rim calcification translated to increased overall growth rate

Reference

An, T. J., Chen, X., Omar, O. M., Sutphin, P. D., Irani, Z., Wehrenberg-Klee, E., Iqbal, S., & Kalva, S. P. (2024). The natural history of splenic artery aneurysms: Factors that predict aneurysm growth. Journal of Vascular and Interventional Radiology, 35(7), 972–978. https://doi.org/10.1016/j.jvir.2024.04.007

Click here for abstract

Study design

Retrospective

Funding Source

None

Setting

Single academic institution-Mass General Hospital

Figure

Plots of the mean growth rate of splenic artery aneurysms (SAAs) based on different aneurysm characteristics. (a) SAAs with greater than 50% mural thrombus were associated with an increased rate of growth (0.65 mm/y). (b) SAAs with greater than 50% rim calcification were associated with a decreased rate of growth (0.14 mm/y). (c) SAAs greater than 2 cm in diameter cm were associated with an increased rate of growth (0.41 mm/y). (d) There was no significant difference in SAA growth rate based on aneurysm location. Error bars on the graphs denote the standard error of the mean. Double asterisks (∗∗) denote statistical significance (P < .05).

Summary

Splenic artery aneurysms (SAAs) are the third most common type of abdominal aneurysm, and represent up to 60% of visceral artery aneurysms. Despite their low incidence (0.8% at arteriography and 0.04%-0.1% at autopsy), increased use of cross-sectional imaging has led to more frequent incidental detections of splenic artery aneurysms. Higher incidences are noted in women and patients with conditions such as atherosclerosis, vasculitis, vasculopathy, and portal hypertension. Although typically asymptomatic, splenic artery aneurysms can rupture and cause life-threatening hemorrhages, with increased rupture risks associated with pregnancy, portal hypertension, pseudoaneurysm, and concurrent vasculitis. Both endovascular and surgical treatments for SAAs show high success and low mortality rates, particularly for asymptomatic aneurysms larger than 2 cm.

This study was done to look at progression of splenic artery aneurysms to ascertain any predictive factors for increased growth which may ultimately lead to life-threatening rupture. This retrospective study used 30 years of patient imaging from 1990-2020 encompassing 132 patients with median age of 66.6 years who had multiple cross-sectional CT and/or MR studies. Patients were excluded if they were under 18, those who had previous correction by endovascular or surgical intervention, and those with splenic pseudoaneurysms or false aneurysms. Multivariable linear regression was performed using aneurysm growth rate as a continuous dependent variable.

In the study, 89% of the patients had a history of hypertension, 64% history of smoking, 31 % with a history of diabetes and 11% with a history of portal hypertension. Most splenic artery aneurysms (61%) remained stable, with a low median growth rate of 0.60 mm/year. Splenic artery aneurysms with >50% of mural thrombus, and a baseline size greater than 2 cm, had increased rates of splenic artery aneurysmal growth. Splenic artery aneurysms with greater than 50% rim calcifications were negatively correlated with aneurysm growth rates. 88% of patients were managed conservatively.

Overall, the authors conclude that there is a trend toward nonoperative surveillance and increased endovascular intervention in the management of splenic artery aneurysms. Formal published guidelines were based on retrospective data, recommending treatment for nonruptured splenic artery aneurysms greater than 3 cm, those increasing in size, or in high-risk patients. Based on the data presented in the current series, for patients with positive predictive factors including baseline size > 2 cm and > 50% mural thrombus, preventive interventions may be warranted. Limitations include the retrospective design, non-standardized protocols, low incidence of adverse events, and potential imaging modality discrepancies.

Commentary

The authors initially found large proportion of the cohort to have existing comorbid conditions of smoking, diabetes, and hypertension with known involvement in aneurysmal formation and growth. Nevertheless, statistical analyses revealed that the factors associated with aneurysmal growth, specifically in the context of splenic artery aneurysm, were mural thrombus, baseline size, and rim calcifications. These new predictors can guide procedural timing in those with increased risks of life-threatening rupture.

It is often informative to utilize large amounts of data obtained over time to uncover obscure trends; but this approach can also carry significant bias and blind us from evolving environmental factors that could have influenced these patients’ disease course. In addition, it may overlook technological advances in diagnostic imaging in the long timespan, which could have implications in aneurysmal diameter measurements and growth rate calculations. To expand on the current study design would entail prospective data and diverse patient populations. Optimal timing for referral to endovascular or surgical intervention, and follow-up interval estimation, will be the next steps.

Post Author
Christopher Loiselle, DO, MS
PGY-1 General Surgery
Rutgers-Robert Wood Johnson Medical School
@Caloiselle