Mitral Annular Calcification Severity Predicts Outcomes in Severe Aortic Stenosis Patients Undergoing TAVR

Avatar
By Dami Aladesanmi on

Key Points:

  • The presence of mitral annular calcification (MAC) in prior studies of transcatheter aortic valve replacement (TAVR) has been associated with poor outcomes, but these studies used semiqualitative assessment, whereas quantitative assessment has generally not been analyzed
  • The CT-derived MAC score is a quantitative assessment that can used in patients undergoing TAVR, but its clinical significance has not been assessed
  • In this study, MAC scores of moderate or severe were associated with increased mortality risk, and involvement of the anterolateral trigone (one component of the score) was independently associated with adverse outcomes
  • The CT-derived MAC score may be a useful quantitative assessment of risk in severe AS patients requiring TAVR

The calcification that precipitates aortic stenosis (AS) can also result in mitral annular calcification (MAC). In previous studies, the presence of MAC has been associated with poorer outcomes following transcatheter aortic valve replacement (TAVR). These studies used semiqualitative MAC assessment, but quantitative assessments have generally not been examined. One recently developed objective quantitative measure of MAC is the CT-derived MAC score in patients undergoing TAVR, but the clinical significance of this measurement has not been investigated. This study aimed to explore the association between quantitative MAC score and outcomes, primarily mortality, in severe AS patients post-TAVR.

The study identified 785 patients who underwent TAVR from 2010 to 2020 for severe AS. MAC scores were calculated from pre-TAVR CT scans within 90 days of baseline echocardiography. MAC scores were based on multiple parameters: CT calcium thickness (<5 mm =1 point, 5-9.99 mm = 2, ≥10 mm = 3), distribution in annular circumference (<180 degrees = 1, 180-270 degrees = 2, ≥270 degrees = 3), trigone involvement (none = 0, anterolateral = 1, posteromedial = 1), and leaflet involvement (none = 0, anterior = 1, posterior = 1) for a total score of 0 to 10 points. Based on these scores, patients were categorized into different levels of MAC severity: none (0 points), mild (1-3 points), and moderate/severe (4-10 points).

The study population was notable for average age 79 ± 9 years and 40% female with overall aortic valve area (AVA) 0.82 ± 0.15 cm2, LVEF 58 ± 13%, aortic valve mean gradient (MG) 46 ± 12 mmHg, and MAC score 2.8 ± 2.5. Both groups had similar proportions of moderate-to-severe MR. MAC score was mild in 304 patients (39%), moderate in 190 (24%), and severe in 73 (9%).

The study found that moderate or severe MAC was associated with increased risk of mortality (adjusted HR 1.556; 95% CI 1.201-2.017, p=0.001). Furthermore, when the individual components of the MAC score were analyzed, the involvement of the anterolateral trigone was independently associated with worse outcomes (adjusted HR 1.455; 95% CI 1.113-1.902, p=0.006).

Ultimately, this study demonstrated that higher MAC scores were significantly associated with increased mortality post-TAVR. Importantly, the involvement of the anterolateral trigone was an important prognosticator of mortality and could be a marker for more severe mitral valve disease. For future patients with severe AS pending TAVR, the authors argue that assessing the MAC score and its components may be important for risk stratification and procedural management.