Abstract Body (Do not enter title and authors here): Introduction: Mitral annular calcification (MAC) often coexists with aortic stenosis (AS) and has been linked to poorer outcomes following transcatheter aortic valve replacement (TAVR) in previous studies utilizing semiquantitative MAC assessment. The clinical significance of the recently developed objective quantitative computed tomography (CT)-derived MAC score in patients undergoing TAVR has not been previously examined.
Goals: To explore the association between quantitative MAC score and outcomes in severe AS patients post-TAVR.

Methods: Patients undergoing TAVR from 2010 to 2020 for severe AS were identified. MAC scores, calculated from pre-TAVR CT scans within 90 days of baseline echocardiography, were based on CT calcium thickness (<5 mm =1 point, 5-9.99 mm = 2, ≥10 mm = 3), distribution in annular circumference (<180° = 1, 180-270° = 2, ≥270° = 3) trigone involvement (none = 0, anterolateral = 1, posteromedial = 1), and leaflet involvement (none = 0, anterior = 1, posterior = 1) for a total score 0-10 points, and patients were categorized into no (0), mild (1-3), moderate/severe (4-10) groups. The primary outcome was overall mortality.

Results: Among 785 patients (mean age 79±9 years, 40% female) overall AVA was 0.82±0.15 cm2, LVEF 58±13%, MG 46±12 mmHg, MAC 2.8±2.5. MAC 2.8±2.5. There was no significant difference in the prevalence of moderate to severe MR between the MAC severity groups (p=0.775). MAC score was mild in 304 (39%), moderate in 190 (24%), and severe in 73 (9%); ≥moderate MAC was independently associated with increased mortality (adjusted HR 1.556; 95% CI 1.201-2.017, p=0.001). Of the individual components of MAC score, involvement of the anterolateral trigone was strongly independently associated with worse outcomes (adjusted HR 1.455; 95% CI 1.113-1.902, p=0.006).

Conclusion: Higher MAC scores are associated with increased mortality post-TAVR. Involvement of the anterolateral trigone emerged as an important prognosticator and may be a marker of more extensive or malignant mitral annular disease. Assessing MAC scores and components pre-TAVR may help improve risk stratification and management.