Hemodynamic Stress Test in Severe Mitral Regurgitation (HEMI)

The preferred treatment of organic mitral regurgitation (MR) is mitral valve repair. Optimally this should be timed so late that it commensurate with the risk of surgery and before irreversibly damage of the heart and pulmonary vessels. The aim is to obtain an understanding of the differences between the symptomatic and asymptomatic patient.

The study will test

A: Symptomatic organic MR is characterized by higher filling pressure, and higher stroke work during physical strain compared with asymptomatic MR.

B: The extent of myocardial fibrosis is associated with filling pressure and cardiac index 1 year after mitral valve repair.

C: Filling pressure can be estimated non-invasively by echocardiography. To test this 40 patients with asymptomatic MR and 40 symptomatic will undergo a stress echocardiography with simultaneous echocardiography and invasive measurement of central hemodynamics. In addition a pulmonary function test and cardiac MRI will be performed.

Background

Degenerative mitral valve disease is the most common cause of organic mitral regurgitation in the Western World. The preferred treatment of organic mitral regurgitation is mitral valve repair. Optimally this should be timed so late that it commensurate with the risk of surgery and before irreversibly damage of the heart and pulmonary vessels. According to the current guidelines mitral valve surgery is indicated in symptomatic patients with severe MR or in presence of known risk factors. The optimal timing of surgery is still controversial in the asymptomatic patients without risk factors.

The overall aim of the present study is to obtain a better understanding of the central hemodynamics at rest and during physical exercise in both symptomatic and asymptomatic patients with organic mitral regurgitation, the relation to neurohormonal activation and myocardial fibrosis, and to identify noninvasive echocardiographic measures suitable for estimation of this.

A epidemiologic sub-study aims to asses whether MR is associated with inherence, as familial clustering of mitral regurgitation earlier has been suggested based only mainly on small observational studies, and case reports.

Methods

The study will test

A: Symptomatic organic MR is characterized by higher filling pressure, and higher stroke work during physical strain compared with asymptomatic MR.

B: The extent of myocardial fibrosis is associated with filling pressure and cardiac index 1 year after mitral valve repair.

C: Filling pressure can be estimated non-invasively by echocardiography.

To test this 40 patients with asymptomatic MR and 40 patients with symptomatic MR will undergo a stress echocardiography with simultaneous echocardiography and invasive measurement of central hemodynamics. In symptomatic patients that undergo surgery, the examination will be repeated 1 year after the surgical mitral valve repair.

In addition pulmonary function test, maximal oxygen consumption test and cardiac MRI will be performed.

The Danish Twin Registry and The Danish National Patient Registry will be used to identify twins with MR. The hypothesis is that the concordance rate is higher in monozygotic twins compared to dizygotic twins.

Eligibility Criteria:
Inclusion Criteria:

* Organic mitral valve regurgitation with effective regurgitation orifice (ERO)\>0.3 cm2
* Age \> 18 years
* Left ventricular ejection fraction (LVEF) \> 60% assessed by echocardiography
* Signed informed consent

Exclusion Criteria:

* Poor echocardiographic window
* Inability to perform bicycle exercise testing
* Ischemic or functional (secondary) mitral valve regurgitation
* Chronic atrial fibrillation/flutter
* Hemodynamic significant aortic valve disease assessed by echocardiography.
* Treatment with oral anticoagulants