Patient Selection for Surgery vs Surveillance in Moderately Dilated Ascending Aorta: Insights From Treatment in Thoracic Aortic Aneurysm: Surgery versus Surveillance (TITAN:SvS), an International Prospective Trial.

Abstract

Background: Guidelines for treating ascending thoracic aortic aneurysms (ATAA) are largely based on single-center studies. To understand factors influencing patient selection for surgery vs surveillance, patient and aneurysm characteristics were compared for patients in the randomized and registry arms of a large prospective, multicenter, multinational trial.

Methods: TITAN:SvS (Treatment in Thoracic Aortic aNeurysm: Surgery versus Surveillance) is a large prospective multicenter study of patients with ATAA between 5.0 and 5.4 cm, randomizing patients 1:1 to initial surgery vs surveillance. Nonrandomized patients are enrolled into a registry where results of operative or surveillance strategy can be monitored prospectively. Between 2018 and 2023, 615 patients were enrolled at 22 sites in the United States and Canada. Demographic and aneurysm characteristics were compared between randomized and registry arms.

Results: Compared with randomized and operative registry groups, patients in the surveillance registry were older with more comorbidities. No significant differences were observed in maximal ascending aortic diameter (5.1 cm [interquartile range, 5.0-5.2 cm] vs 5.1 cm [interquartile range, 4.9-5.2 cm] P = .2) or other aneurysm characteristics. Despite similar numbers of enrolling centers in the United States (n = 11) and Canada (n = 12), Canadian patients were more likely to be randomized (58% vs 7%, P < .01) and less likely to be enrolled in the operative (9% vs 42%, P < .01) or surveillance registry (34% vs 51%).

Conclusions: Enrollment data for TITAN:SvS suggest that patient and geographic characteristics, rather than aortic size, influence decision-making regarding the initial treatment strategy for ATAAs. These findings highlight the need for caution when generalizing outcomes from operative registries, because sicker patients may be excluded.