Is the Cause of Mitral Regurgitation Relevant for MitraClip?

Mitral regurgitation (MR) is the most common valvulopathy: it is present in (at least) 7.5% of patients >75 years old.

This pathology can be classified as primary or degenerative MR (DMR) and secondary or functional MR (FMR).

FMR can be caused by dilatation of the left atrium (most often due to atrial fibrillation), occurring in 27% of cases (a-FMR), or by involvement of the ventricle, known as ventricular FMR (v-FMR).

Whether the MitraClip strategy is similar in these contexts is yet to be determined.

The analysis included a total of 1044 patients with MR. Among them, 423 had DMR and 621, FMR. Among the latter, 505 cases were v-FMR and 116, a-FMR.

The primary endpoint (PEP) was all-cause mortality and hospitalization due to heart failure at 2 years of follow-up.

The mean patient age was 76.3 years old; 40% of subjects were female and the Society of Thoracic Surgeons (STS) score was 8.6%.

Patients with v-FMR were younger, but had higher STS scores (9.3%). In the a-MRF group, there were more women and greater evidence of atrial fibrillation.

There were no differences in comorbidities nor in the New York Heart Association functional class.

In the echocardiographic findings, those with v-FMR had greater ejection fraction and larger ventricle diameters; those in the a-FMR group had a large left atrium and small ventricular diameters. In cases caused by DMF, the effective regurgitant orifice area was greater. No difference was observed as regards pressure in the pulmonary artery.

There were no differences in procedure time, fluoroscopy time, or final outcome. Fewer clips were used in a-FMR patients.

The PEP was in favor of DMF compared with v-FMR and a-FMR (42.3% vs. 31.5% vs. 21.6%; p < 0.001), respectively.

Mortality was higher in those who presented a-FMR compared with DMR, and somewhat lower compared with those who presented v-FMR.

The presence of tricuspid regurgitation was associated with higher mortality regardless of the cause of MR.