Abstract 4366354: Unmasking Risk: Clinical Outcomes of Moderate Aortic Stenosis with Concomitant Mitral Regurgitation—A Cardiac MRI-Based Evaluation

Objective: The clinical trajectory of patients with moderate aortic stenosis (AS) complicated by concomitant mitral regurgitation (MR) remains poorly defined. While management strategies in severe AS are well established, patients with moderate AS and MR often fall below guideline-based thresholds for intervention despite symptoms and remodeling. We used cardiac magnetic resonance (CMR)—a robust modality for accurate valve quantification, particularly in mixed valvular disease— to assess the prognostic impact of MR in moderate AS and to compare the outcomes to patients with severe AS. Methods: We analyzed consecutive patients from the DeBakey CMR Registry (2008–2023) with ≥moderate AS on clinically indicated CMR. Exclusions included >mild aortic regurgitation or mitral stenosis, subaortic obstruction, infiltrative cardiomyopathies, pre-capillary pulmonary hypertension, advanced malignancy, or unavailable follow-up. Patients were stratified by AS severity (moderate vs. severe) and MR grade (<moderate vs. ≥moderate), with valve severity assessed per current CMR guidelines. The primary outcome was a composite of cardiovascular death or heart failure hospitalization. Statistical analysis was performed in R (Vienna, Austria), with significance defined as p<0.05. Results: In a multivariate Cox regression analysis of 422 patients with moderate AS, both mitral regurgitant (MR) fraction on CMR (hazard ratio [HR] per 5% increase: 1.10; 95% CI: 1.04–1.16; P < 0.001) and the presence of ≥ moderate MR (HR: 1.86; 95% CI: 1.31–2.65; P < 0.001) were independently associated with the composite outcome (Table 1). In moderate AS, penalized spline regression analysis showed a statistically significant increase in risk with increasing MR fraction (P<0.001 for linearity; P=0.028 for non-linearity; Figure 1). Kaplan-Meier curves demonstrated poorer 3-year event-free survival in patients with moderate AS and concomitant ≥moderate MR (33%) compared with both isolated severe AS (71%) and severe AS with ≥moderate MR (49%) (Figure 2). Conclusion: In moderate AS, concomitant MR is an independent predictor of adverse clinical composite outcomes. Patients with moderate AS and ≥moderate MR had worse composite outcomes than those with isolated severe AS, underscoring the additive risk of dual-valve pathology. These findings support more vigilant monitoring and may justify re-evaluation of treatment thresholds in this mixed valvular disease subgroup.