Aims: To investigate the value of assessment of mitral regurgitant fraction (RF) using left ventricular (LV) volumes obtained by 3 dimensional echocardiography (3DE) to quantify primary mitral regurgitation (MR).

Fifty-one patients with primary MR in sinus rhythm were prospectively enrolled. RF was calculated using either 2DE or 3DE LV volumes obtained as follows: (LV total stroke volume - LV forward stroke volume by Doppler) / LV total stroke volume. Severity of MR was graded independently using an integrative approach, as recommended by current guidelines.

The 3D method had a feasibility of 89%. A significant correlation was observed between grade of MR severity and 3D RF(r=0.84, P<0.0001) and 2D RF (r=0.74, P<0.0001). The area under the ROC curves for ≥3+ or 4+ MR was 0.99 for 3DRF and 0.94 (0.83 to 0.99) for 2D RF. All patients with 3DRF ≥40% had ≥3+ or 4+ MR and all patients with 3DRF ≤30% had 1+ or 2+ MR with a “grey” overlap zone between 30 and 40%.

RF can be routinely determined using 3D LV volumes with a high feasibility in patients with primary MR and is reliable for identification of severe MR. This 3D method should be included in the currently recommended multiparametric integrative approach.