Myxomatous mitral valve prolapse (MMVP) is characterized by excessive leaflet tissue leading to a wide spectrum of mitral regurgitation (MR) ranging from trivial to complex severe incompetence. The prolapse volume (PV) below the prolapsing leaflets in end-systole was recently suspected to impact both chamber remodeling and MR grading in Barlow's disease. The aims of the current study using Cardiac magnetic resonance (CMR) was (i) to assess the interaction between PV and cardiac chambers size and function (ii) to study the impact of PV on MR grading in Barlow's disease.

Over a 60-months period, 157 patients (45 women; mean age 62±15) consecutively referred at the Monaco Heart center, Monaco for CMR assessment of primary MR secondary to MVP either from MMVP (n=91; 58%) or fibroelastic disease (FED) (n=66; 42%)were eligible for inclusion into the study. Over the same period, we enrolled 52 age and sex-matched controls. Patients were imaged with a 3-Tesla Siemens Skyra scanner. Prolapse volume (PV) was calculated on the end systolic frame in each of the 4-, 3- and 2-chamber views.

Despite similar left ventricular (LV) size, PV was larger in MMVP (11±9ml) than in FED (2±2ml). PV progressively increased with the severity of MR in MMVP but not in FED. PV correlated significantly (r=0.52) with the LV dilatation in severe MR but also in less than moderate MR. Despite a low RegV by CMR (32±18ml), some MMVP patients with less than moderate MR exhibit significant cardiac chambers remodeling compared to the 52 controls. In MMVP, PV>14ml was associated with a significant underestimation (Bias=−26±32ml) of RegV by PISA compared to CMR (Fig. 1).

In conclusion, in MMVP, PV may play a role in left cardiac chambers remodeling, even in patients without severe MR, and in discordant grading of MR between echocardiography and CMR.