International Multicenter Registry of Patients With Concomitant Aortic and Mitral Valve Disease Undergoing Transcatheter Aortic Valve Implantation - The Aortic+Mitral TRAnsCatheter (AMTRAC) Valve Registry

Transcatheter aortic valve implantation (TAVI) , has revolutionised the treatment for severe aortic stenosis (AS) over the past decade. The use of TAVI is growing exponentially, and the current trend of treating younger and lower risk patients is expected to continue [1], with TAVI eventually becoming the treatment of choice for the majority of severe AS patients. When treating younger, lower risk patients, whose life expectancy is longer than that of current typical TAVI patients, long term prognosis with good functional status is as significant as periprocedural morbidity when selecting the preferred treatment strategy. Consequently, treatment of comorbidities, especially cardiac comorbidities is of paramount importance.

Significant mitral regurgitation (MR) is present in approximately 25% of patients with severe AS [2], there are several pathophysiological mechanisms linking the two entities [3,4]. Significant MR is associated with worse prognosis in patients undergoing either surgical aortic valve replacement (SAVR) [5] or TAVI [6,7] . Using a surgical intervention, both AS and MR can be treated (albeit at a cost of increased perioperative mortality) [8], while treating both valves using a transcatheter technique in a single procedure is not customary. A sizeable fraction of patients from AS+MR will have some reduction in MR following TAVI [2], but unlike the case of surgical double valve replacement [6], the prognostic benefit of MR reduction following TAVI has not yet been shown [9].This issue may be of utmost importance in patients who are viable surgical candidates, in whom the feasibility of total surgical valvular treatment may be a "tiebreaker" when contemplating the pros and cons of transcatheter vs. surgical intervention.

The percutaneous treatment options for MR with either transcatheter mitral valve replacement (TMVR) or repair (TMVr) are expanding and clinical experience is growing [1], raising the option for a combined percutaneous treatment for patients with AS+MR - either a combined TAVI + TMVR/r procedure, or performing TAVI first followed by a TMVR/r for those patients whose MR does not improve sufficiently following an isolated TAVI. One multicentre study from Spain dedicated to patients with significant MR undergoing TAVI found two predictors for persistence of MR following TAVI (mitral annular diameter of >35.5 mm and the degree of calcification of the mitral apparatus by multidetector computed tomography), and also suggested that only a small fraction of such patients will be suitable for TMVR/r, but this was based on a small number of patients (n=177) [10].

To examine whether such approach is appropriate, several evidence gaps will need to be addressed:

1. describing the characteristics and outcomes of current patients undergoing aortic + mitral transcatheter heart valve procedures.
2. Better understanding of the predictors for MR regression following isolated TAVI and consequently estimating the fraction of patients who will be suitable for TMVR/r post TAVI
3. Examining the clinical outcomes of patients with significant MR post TAVI who subsequently underwent TMVR/r compared to those left for medical management.