Abstract 19347: Systematic Differences in Left Ventricular Volumes Measured by Cardiac MR and Biplane Echocardiography in Moderate-Severe Mitral Regurgitation.
Systematic differences between left ventricular (LV) volumes measured by cardiac magnetic resonance (CMR) and 2D echocardiography have been reported: 2D echo significantly underestimates LV volumes. Mitral regurgitation (MR) due to mitral valve prolapse (MVP) is associated with LV volume overload and remodelling, including increased chamber sphericity. We compared LV volumes in 25 patients (pts) with MVP and at least moderate MR by CMR and echo on 2 different days, 2-4 weeks apart.
Methods: Echo LV volumes were measured off-line using Simpson's biplane method. CMR used gated cine images (6 longitudinal and 6 short axis slices). LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV) and ejection fraction (EF) were measured on each day, and the differences examined using the method of Bland and Altman and coefficient of variation (CV).
Results: Age 61 years, 84% male, all in sinus rhythm. A systematic difference was observed between the LV volumes measured by each methods: both LVEDV and LVESV were significantly larger by CMR, but the EF was only slighter different (see table). There was excellent agreement between the visits for both techniques, although the between days CV was higher for the echo (LVEDV 13%, EF 10%) than CMR (LVEDV 4%, EF 4%). Although good correlation was observed between the methods for LVEDV and EF, the Bland and Altman plots confirmed a systematic bias and a non-linear relationship, suggesting that the difference between echo and CMR was greater at higher LVEDV.
Conclusion: There was a systematic and large difference in LV volumes observed between CMR and echo in these pts with MVP and moderate-severe MR, showing that the volumes obtained by these methods may not be interchangeable. Importantly, this systematic bias was not constant and increased with larger volumes and thus may change as the severity of MR and LV dilatation progresses. This may result in important misclassification of the degree of LV dilatation in patients with MVP and severe MR.
- © 2010 by American Heart Association, Inc.