Grading of mitral regurgitation in mitral valve prolapse using the average pixel intensity method

We recently reported the feasibility of the average pixel intensity (API) method for grading mitral regurgitation (MR) in a heterogeneous MR population. Since mitral valve prolapse (MVP) is an important cause of primary MR, we more specifically investigated the feasibility of the API method and the MR flow dynamics in patients with MVP.

Transthoracic echocardiography was performed by a single operator in consecutive MVP patients (n=112). MR was assessed using the API method, color Doppler, vena contracta width (VCW), effective regurgitant orifice area (PISA-EROA) and regurgitant volume (PISA-RV).

The API method was feasible in 89% of all MVP patients (68%, 71% for VCW and PISA method, respectively ;p<.001). Inter- and intra-observer correlations for API in MVP with non-holosystolic MR were 0.989 and 0.995. For the overall MVP-MR population, API had significant correlations with direct and indirect measures of MR severity. Based on ROC curves, an API cutoff value of 125 au was suggested to identify severe MR in MVP and a MR duration/systolic time ratio<100% (i.e. non-holosystolic MVP-MR) identifies patients with non-severe MR (API<125), whereas the majority of holosystolic MVP had severe MR (API>125). Finally, API analysis of the proto-, mid- and telesystolic phases of MR in MVP showed different kinetics in non-holosystolic compared to holosystolic MVP.

The API method is a feasible and reproducible method for grading MVP-MR. As the API method takes into account the temporal MR flow changes during the entire systolic cycle, it may be of added value in clinical practice.