Combined Significant Aortic Stenosis and Mitral Regurgitation: Challenges in Timing and Type of Intervention.

In this narrative review, we aim to summarize the literature surrounding the assessment and management of the common, yet understudied combination of aortic stenosis (AS) and mitral regurgitation (MR), the components of which are complexly interrelated and interdependent from diagnostic, prognostic, and therapeutic perspectives. The haemodynamic interdependency of AS and MR confounds the assessment of the severity of each valve disease, thus underscoring the importance of a multimodal approach integrating valvular and extra-valvular indicators of severity. A large body of literature suggests that baseline MR is associated with reduced survival post aortic valve (AV) intervention and that regression of MR post-AV intervention confers a mortality benefit. Functional MR is more likely to regress after AV intervention than primary MR. The respective natural courses of the two valve diseases are not synchronized; therefore, significant AS and MR at or above the respective threshold for intervention might not coincide. Surgery is primarily a one-stop-shop procedure due to a considerable perioperative risk of repeat interventions, whereas transcatheter treatment modalities allow for a more tailored timing of intervention with re-assessment of concomitant MR after AV replacement and a potential staged intervention in the absence of MR regression. In summary, AS and MR, when combined, are interlaced into a complex haemodynamic, diagnostic and prognostic synergy, with important therapeutic implications. Contemporary approaches should consider stepwise intervention by exploiting the advantage of transcatheter options. However, evidence is needed to demonstrate the efficacy of different timing and therapeutic options