Abstract 15253: Significant Discrepancies in Quantification of Regurgitant Volume in Primary Mitral Regurgitation Observed on Multimodality Imaging: Is It Time for Reappraisal?

Introduction: Mitral valve regurgitation volume (RV) can be quantified using proximal isovelocity surface area (PISA) or stroke volume (SV). SV method incorporates mitral annulus (MA) diameter (assumed circular) on 2D transthoracic echo (2D TTE). However, MA area (MAA) can be precisely measured using 3D transesophageal echocardiographic (3DTEE) or computed tomography (CT). Hypothesis: We sought to compare RV obtained using a) PISA b) standard SV using MA diameter on 2D echo and c) modified SV using MAA on 3D TEE and d) MAA on CT. Methods: 37 patients (63±9 years, 81 % men) with severe primary mitral regurgitation (MR) undergoing surgery were prospectively recruited. RV was calculated using a) PISA b) standard SV method using MA diameter on 2D echo (0.785*diameter 2 MV *VTI MV -0.785*d 2 LVOT *VTI LVOT ) c) & d) modified SV methods where MAA (on 3D TEE and CT) were incorporated instead of MA diameter. Results: The mean MAA (cm 2 ) by 2DTTE, 3DTEE & CT were 10.7±3, 10.9 ±3 & 15.9 ±3. Mean RV (cc) by standard SV method, modified SV (3D TEE & CT) & PISA were 294±126, 276±82, 355±127 & 91±51, respectively. Correlations & agreements of SV-based RV are shown in Figure 1. RV was highest using CT-based MAA. The closest agreement was between 2D TTE & CT with a mean error (ME) of -61 cc. There was a large discrepancy in RV derived from PISA vs all SV methods, with a systemic overestimation using SV methods with root mean square errors (RMSE) ranging from 156 to 293 cc Figure 2. Conclusions: In severe MR,calculating RV using SV vs PISA yields vastly different values. The differences are exaggerated using modified SV method incorporating more accurate MAA on 3D TEE or CT. These techniques should not be interchanged to quantify MR.