Mitral regurgitation and unmet therapeutic needs
Mitral Regurgitation is a structural heart disease that affects about 10% of the world’s population over 75 years of age.
With the life expectancy increase, the prevalence of these valve diseases continues to rise in Western countries and is now the second most common heart valve disease in terms of frequency. The mitral valve ensures unidirectional blood flow from the left atrium to the left ventricle.
The mitral valve ensures unidirectional blood flow from the left atrium to the left ventricle. Mitral regurgitation, is the dysfunction of this valve where a certain amount of blood, depending on the degree of insufficiency, is returned from the ventricle to the atrium during ventricular contraction. This blood regurgitation is leading to a decrease in heart function, dilation of the left ventricle and left atrium. It is responsible for patient dyspnea, deterioration of quality of life, progression to heart failure and even death.
Figure 1 : Anatomical illustration of the heart with a focus on the normal and pathological mitral valve with a coaptation defect of the valve leaflets causing mitral insufficiency.
Primary MR, also called degenerative MI (DMR), is due to structural abnormalities affecting the valve itself, the valve system or the sub-valvular system. These are most often degenerative diseases.
Secondary or functional MR (FMR) is due to an abnormality of the ventricular muscle that may be dilated, or a dysfunction secondary to a myocardial infarction. Under these conditions, the valve leaflets are usually intact. This category of patients is more fragile and at high surgical risk.
The treatment of choice for severe mitral insufficiency is surgical treatment. The goal of this treatment is to restore effective valvular continence either by repairing valve or sub-valvular lesions or by replacing the defective valve with an artificial valve.
The existence of an associated comorbidity and the presence of left ventricular systolic dysfunction are elements that make surgery not proposed to patients due to the high surgical risk. As a result, barely 50% of patients with severe mitral insufficiency are operated on, while the other patients deemed too high surgical risky remain without effective treatment.
For this category of patients, transcatheter valve replacement therapy can be a less invasive and as effective alternative to surgical treatment.
There are two delivery approaches: the trans-apical approach and the trans-femoral trans-septal approach.
The trans-femoral/trans-septal (TF/TS) approach is the less invasive and less traumatic. It consists in introducing the delivery system by puncturing the femoral vein and delivery it through the atrial septum to reach the mitral valve.
In order to use this preferred approach, certain technological barriers must be overcome, including the possibility of introducing large valve devices into small catheter sheaths while maintaining a high degree of flexibility to facilitate anatomical navigation by following an acute-angle trajectory. This technological challenge requires a technological paradigm shift.