Determinants of the Progression and Outcome of Mitral Regurgitation
Determinants of the Progression and Outcome of Mitral Regurgitation
Mitral regurgitation (MR) is one of the most frequent valve lesions, both in North America
 and in Europe, and its prevalence is increasing with the aging of the population. Organic
 Mitral Regurgitation (OMR) and Ischemic Mitral Regurgitation are the 2 main categories of MR.
 Organic or primary MR is caused by an anatomic alteration of the valvular or subvalvular
 mitral apparatus and refers to rheumatic MR and degenerative MR that includes mitral leaflet
 prolapse and flail leaflet. In the past 20 years, degenerative MR has become, by far, the
 most frequent cause of severe MR leading to surgery in the western world. However, the best
 current treatment for OMR remains uncertain and controversial. We have obtained preliminary
 data showing that OMR is a dynamic lesion. Hence, the echocardiographic evaluation of MR at
 rest, as generally performed during routine clinical exam, does not necessarily reflect the
 status of MR during patient's daily activities and thereby does not adequately assess the
 risk of rapid progression and poor outcome in these patients. The objective of this study is
 to identify the independent predictors of disease progression and outcome in patients with
 asymptomatic chronic OMR and to develop and validate novel imaging and circulating biomarkers
 to improve risk stratification and therapeutic decision-making process in patients with
 chronic asymptomatic primary OMR.
Mitral regurgitation (MR) is one of the most frequent valve lesions, both in North America
 and in Europe, and its prevalence is increasing owing to the aging of the population. There
 are 2 main categories of MR: Organic Mitral Regurgitation (OMR) and Ischemic Mitral
 Regurgitation. Organic or primary MR is caused by an anatomic alteration of the valvular or
 subvalvular mitral apparatus and refers to rheumatic MR and degenerative MR that includes
 mitral leaflet prolapse and flail leaflet. In the past 20 years, degenerative MR has become,
 by far, the most frequent cause of severe MR leading to surgery in the western world.
 However, the best current treatment for OMR remains uncertain and controversial. This is, in
 large part, due to the lack of prospective data on the determinants of OMR progression and
 outcome. Furthermore, we have obtained preliminary data showing that OMR is a dynamic lesion.
 Hence, the echocardiographic evaluation of MR at rest, as generally performed during routine
 clinical exam, does not necessarily reflect the status of MR during patient's daily
 activities and thereby does not adequately assess the risk of rapid progression and poor
 outcome in these patients.

 The general objective of this study is thus: to identify the independent predictors of
 disease progression and outcome in patients with asymptomatic chronic OMR and to develop and
 validate novel imaging and circulating biomarkers to improve risk stratification and
 therapeutic decision-making process in patients with chronic asymptomatic primary OMR.

 The specific aims of the study are: (1) To obtain and analyze: a) the dynamic changes in MR
 severity, pulmonary arterial pressure, and LV function during exercise; b) the maximum
 exercise capacity; c) the metabolic profile; d) the plasma natriuretic peptides, e) the
 degree and localization of myocardial fibrosis measured by cardiac magnetic resonance Imaging
 (MRI); f) the blood markers of myocardial extracellular matrix (ECM) turnover; g) the
 progression of MR severity and LV dysfunction during follow-up; and h) the occurrence of
 adverse clinical outcomes (i.e. symptoms, LV dysfunction, atrial fibrillation (Holter ECG),
 pulmonary hypertension, heart failure, cardiovascular death) during follow-up in a series of
 440 patients with at least moderate OMR and no symptoms at baseline. (2) To analyze the valve
 tissue samples explanted from the patients who will undergo mitral valve repair with
 quadrangular resection during follow-up in order to document the presence of lipids,
 inflammation, and expression of metalloproteinases (MMPs). (3) To obtain and analyze the
 postoperative changes in LV geometry and function, pulmonary arterial pressure, symptoms, and
 exercise capacity in the subset of patients who will undergo mitral valve surgery during
 follow-up. (4) To evaluate the usefulness of the exercise induced changes in MR severity,
 pulmonary arterial pressure, and LV function (i.e. contractile reserve), and of the blood
 levels of natriuretic peptides and ECM biomarkers for the prediction of rapid progression to
 LV dysfunction and adverse events. (5) To examine the relationship between the metabolic
 abnormalities linked to visceral obesity and the progression and outcome of OMR. (6) To
 determine, among the baseline clinical, echocardiographic, MRI, metabolic, and biomarkers
 variables, those which are independently associated with the progression of MR severity and
 LV dysfunction, and the occurrence of adverse clinical outcomes in patients with OMR.
Inclusion Criteria:

 -  Age > 18 or 21 years (Legal age according to the countries involved in this study)

 -  Presence of at least moderate chronic OMR defined as an ERO ≥20mm2 and/or a
 regurgitant volume ≥30mL

 Exclusion Criteria:

 -  MR due to ischemic heart disease or cardiomyopathy

 -  > mild mitral stenosis, aortic regurgitation, aortic stenosis or pulmonary stenosis

 -  previous valve operation

 -  history of myocardial infarction or angiographycally documented coronary stenosis

 -  congenital or pericardial heart disease

 -  endocarditis

 -  contra-indication or inability to exercise

 -  pregnancy

 -  Class I or II indication for mitral valve operation according to the 2006-2007
 ACC/AHA/ESC guidelines

 -  Typical contraindications to contrast-enhanced MRI (surgery in the last 3 months,
 defibrillator, pericardial electrodes, brain surgery, aneurysm clipping,
 neurostimulator, electric stimulation device or magnetically activated, cochlear
 implant, insulin pump or medication delivery device, Swan-Ganz catheter)