Impact of Parietal Calcification on the Natural History of Visceral Aneurysms

Visceral aneurysms (VAs) are rare dilatations of splanchnic arteries that carry a significant risk of rupture. The role of parietal calcification in the natural progression and rupture risk of these aneurysms remains unclear, with most existing literature focusing on abdominal aortic aneurysms. This study aimed to evaluate the relationship between parietal calcification and VA relative growth rates, aneurysm sac thrombosis, and patient survival.

A retrospective analysis of 138 patients diagnosed with VA was conducted at the Hospital das Clínicas, Faculty of Medicine, University of São Paulo. Calcification was assessed via computed tomography and categorized into four types based on circumferential extent. Patients were grouped into low calcification (types 1 and 2) and high calcification (types 3 and 4) categories. The relative growth rate was calculated as the change in aneurysm diameter over time. Kaplan-Meier curves and Cox regression analyses were used to compare survival rates.

Of the 138 patients, 117 had <50% calcification (types 1 and 2) and 21 had >50% calcification (types 3 and 4). Aneurysm growth was higher in the high-calcification group (0.73 mm/year vs. 0.53 mm/year), although not statistically significant (P = 0.42). A higher prevalence of aneurysm thrombosis was noted in the high-calcification group (33.3% vs. 11.1%, P = 0.002). Kaplan-Meier survival analysis revealed a trend toward better 5- and 10-year survival in patients with higher calcification, but this finding was not statistically significant.

In this cohort of 138 patients, parietal calcification involving more than 50% of the aneurysm circumference was associated with a significantly higher prevalence of intra-aneurysmal thrombosis and a marked female predominance. A nonsignificant trend toward higher annual growth and toward better long-term survival was also observed in heavily calcified aneurysms. These findings suggest that parietal calcification may represent a morphological feature with prognostic relevance in visceral aneurysms and support the need for further studies to determine its role in risk stratification and management.