Page 97 - Advanced echocardiography in characterization and management of patients with secondary mitral regurgitation

Introduction
In prior studies of patients with heart failure (HF) and secondary mitral regurgitation (MR), quantification of MR severity, indices of left ventricular (LV) function and remodeling, and clinical symptoms have been the principal parameters used to assess prognosis and select the most appropriate therapy (1,2). Guideline-directed medical therapy (GDMT) for HF is foundational for all patients and may reduce MR by decreasing LV dimensions (3,4). Cardiac resynchronization therapy has been shown to further reduce MR in some patients with HF (5,6). When surgical coronary revascularization is needed, concomitant mitral annuloplasty is often performed (1,2). However, recurrent MR after annuloplasty is not uncommon and has been associated with increased mortality and morbidity (7,8). In patients with non-ischemic cardiomyopathy and severe secondary MR, surgical mitral valve repair has also been associated with high operative risk and its variable durability (7,8). Specific mitral valve geometric abnormalities and the extent of LV remodeling have been associated with recurrence of MR after surgical mitral valve repair and reduced survival (7-10).
More recently, transcatheter mitral valve repair (TMVr) has been introduced for the treatment of HF patients with severe secondary MR, the most widely studied of which is transcatheter mitral leaflet edge-to-edge approximation with the MitraClip. A decade ago, numerous mitral valve anatomic criteria were established that predicted success (or failure) of the MitraClip (11,12). However, these studies were performed before widespread usage of this device. Procedural success rates have greatly improved within the last decade, and in the present era less is known about the mitral valve anatomic parameters that predict procedural success and long-term outcomes with the MitraClip (and may vary in primary and secondary MR). In this regard, disparate outcomes of HF patients enrolled in the Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients With Functional Mitral Regurgitation (COAPT) (13) and the Multicentre Study of Percutaneous Mitral Valve Repair MitraClip Device in Patients With Severe Secondary Mitral Regurgitation (MITRA-FR) (14) trials were reported, which has most often been attributed to inter-study differences in LV dilation, LV function and MR severity. However, a detailed analysis of mitral valve geometry and its interplay with LV remodeling and MR severity in determining the clinical outcomes of patients randomized to MItraClip plus GDMT versus GDMT alone has not been performed in either study. Accordingly, in the present sub-study from the COAPT trial, we assessed the association between various geometric mitral valve parameters and clinical outcomes. We hypothesized that more advanced mitral valve apparatus deformation would be associated with worse outcomes independent of
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