Role of Functional Mitral Regurgitation in Heart Failure with Preserved Ejection Fraction: An Unrecognized Protagonist?: Reply

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We thank Drs Santas, Núñez, and Núñez for their comments related to our paper published in the European Journal of Heart Failure that evaluates the association between functional mitral regurgitation (MR) at discharge and post-discharge outcomes in acute decompensated heart failure (HF) patients with a preserved or reduced EF.1 It is critical to distinguish between degenerative MR and functional MR. In the study under discussion, patients with clinical or echocardiographic evidence of organic valvular or congenital heart disease were excluded. In addition, structural mitral lesions, such as valve prolapse or rheumatic disease, were defined as a degenerative mitral valve disease. That is, in functional MR, the components of the valve (leaflets, chordae tendineae, papillary muscles, and annulus) are structurally normal and MR results from geometrical distortion of the subvalvular apparatus, secondary to LV enlargement and remodelling due to CAD or cardiomyopathy.2, 3 Barasch et al. have reported that mitral annulus calcification is associated with a significant risk of incident HF, cardiovascular and all-cause mortalities, and worse outcome in older patients with pre-existing cardiovascular disease.4 However, we did not have data regarding the association of MR and mitral annulus calcification with outcomes. Accordingly, further investigation needs to be performed into the influence on outcomes of significant functional MR, the presence of mitral annulus calcification, and clinical outcomes in patients with acute decompensated HF. In the setting of acute decompensated HF with a preserved EF, the association of functional MR and pulmonary hypertension with adverse outcomes is very important.2, 3 However, we did not have data regarding tricuspid regurgitation and the presence of pulmonary hypertension in our study. Accordingly, further investigation is needed to evaluate the association between functional MR severity, the presence of pulmonary hypertension, and clinical outcomes in acute decompensated HF patients with a preserved EF. In the present study, patients receiving mitral valve repair (such as mitral valve replacement or percutaneous functional MR repair using a MitraClip) after hospital discharge were defined as readmission for worsening HF after discharge. In addition, the number of mitral valve interventions in preserved or reduced EF during follow-up after discharge was 20 (1.1%) patients and 17 (1.1%) patients, respectively. However, we have no data regarding outcomes of patients receiving mitral valve repair after hospital discharge. We acknowledge that this may be a limitation of our study as the hospitalizations for mitral valve repair were not necessarily caused by worsening HF symptoms. However, there were only a few of these events and they do not change the interpretation of our data. Accordingly, further investigation needs to be performed into the influence on post-discharge outcomes of functional MR and mitral valve repair in patients hospitalized for acute decompensated HF. In our sample, the demographic profiles of groups stratified by functional MR at discharge were similar between patients with preserved and reduced EF. Accordingly, the same multivariate model was used for preserved and reduced EF patients in this study. Furthermore, when we examined the interaction between functional MR severity at discharge and preserved or reduced EF with respect to the composite endpoint of all-cause death and readmission for HF after discharge, there was no evidence for the interaction between functional MR severity at discharge and preserved or reduced EF with respect to the composite endpoint (P = 0.498 for the interaction). However, we believe that acute decompensated HF patients who had a preserved or reduced EF show differences with respect to the association of functional MR at discharge with the outcome following discharge. Therefore, a better understanding of the pathophysiology of HF associated with functional MR at discharge is needed to develop targeted therapy that can improve post-discharge prognosis of acute decompensated HF patients, particularly preserved EF patients. Katsuya Kajimoto Division of Cardiology Sekikawa Hospital 1-4-1, Nishi-Nippori Arakawa-ku Tokyo, 116–0013 Japan Tel: +81 3 3803 5151 Fax: +81 3 3806 6808, E-mail: kkajimoto@gmail.com Teruo Takano Department of Internal Medicine, Nippon Medical School Tokyo Japan

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