Day to day variability of Doppler color flow jets in mitral regurgitation

Department of Internal Medicine (Cardiology Division), University of Texas Southwestern Medical Center, Dallas.

Doppler color flow mapping offers the potential to assess serial changes in mitral regurgitation associated with therapeutic interventions such as surgical valve repair or after-load reduction. However, the day to day variability of color flow jets in mitral regurgitation must be established to distinguish therapeutic responses from random variation. Therefore, 14 patients with mitral regurgitation were each studied on 5 sequential days by color flow velocity mapping. Instrument settings were kept constant for each patient, and no patient had a significant change in heart rate, blood pressure, left ventricular end-diastolic dimension or circumferential wall stress between studies. To assess day to day variability, the area of the Doppler color flow map was carefully measured in multiple views by an experienced echocardiographer. Mitral regurgitant jet area by color flow mapping tended to be greater from apical rather than parasternal views (5.6 +/- 4.0 versus 2.9 +/- 2.1 cm2, respectively, p less than 0.03). The maximal jet area in any view ranged from 0.4 to 15.0 cm2 in individual subjects. Variability of maximal jet area within subjects was not statistically significant by repeated measures analysis of variance (F = 1.88, p = 0.13); however, the coefficient of variation was approximately 15%. Thus, a reduction in jet area of greater than or equal to 30% would be needed to predict a therapeutic response at the 95% confidence level. These data have important implications regarding the use of color flow mapping to assess the efficacy of therapeutic interventions in mitral regurgitation.