A simple non-invasive method to predict the mitral valve geometric orifice area after edge-to-edge repair

The edge-to-edge repair (EtER) technique consists of anchoring the free edge of the diseased leaflet of the mitral valve to the corresponding edge of the opposing leaflet. When the middle sections of the leaflets are sutured, a 'double-orifice' (DO) mitral valve is artificially created. The main consequence of this technique is that mitral valve geometric orifice area (MGOA) is sensibly reduced and a functional mitral stenosis might be created. The study aim was to determine, mathematically, the MGOA by using a simple non-invasive formula following an EtER, and to examine the influence of suture position on the resulting MGOA.

The Lemniscate (also called the Lemniscate of Bernoulli), which has a shape similar to the DO EtER, was used to determine the MGOA following an EtER.

The reduction in MGOA following EtER was more dramatic for mitral valves with a small initial MGOA. For example, a centered suture reduced the MGOA by 54.9% for an initial MGOA of 6.41 cm2; this resulted in an increase in mean transmitral valve pressure gradient (TPG) of 340%, from 0.5 to 2.2 mmHg, corresponding to a mild mitral valve stenosis. In contrast, the reduction was up to 73.5% for an initial MGOA of 3.77 cm2; this resulted in an increase in TPG of 1,339%, from 1.3 to 18.7 mmHg, corresponding to a severe mitral valve stenosis.

Although the DO EtER technique appears to be effective for correcting mitral regurgitation, the significant reduction in mitral valve area may become problematic for the patient. However, this simple mathematical model may help clinicians to determine the reduction in MGOA following EtER.