Impact of chronic lisinopril therapy on left atrial volume versus dimension in chronic organic mitral regurgitation

Abstract

Chronic mitral regurgitation imparts a volume load on the left atrium (LA). Because this chamber may dilate asymmetrically, changes in left atrial size may be underestimated using standard two-dimensional or M-mode techniques. The effect of lisinopril therapy in the setting of chronic organic mitral regurgitation on LA dimension was studied using standard M-mode techniques and LA volumes using the biplane Simpson's method. Mitral regurgitant fraction was reduced at one year in the lisinopril group versus the placebo group (-6.7%+/-3.5% versus 3.5%+/-3.2%, respectively; P<0.05). Significant reductions in both maximum and minimum LA volumes were seen in the lisinopril group (88+/-33 mL to 75+/-23 mL and 46+/-20 mL to 38+/-16 mL, respectively; P<0.01). This change in LA size was not appreciated when measurements were performed using standard M-mode techniques (from 44.3+/-6.9 mm to 44.1+/-7.4 mm; P=not significant). There was no significant relationship between change in LA volume and change in regurgitant fraction or systolic blood pressure. Change in LA volume was moderately correlated with change in left ventricular mass. Angiotensin-converting enzyme inhibitor therapy reduces LA volume in the setting of chronic mitral regurgitation. This change in LA size is not apparent when standard M-mode techniques are used. Therefore, a volumetric assessment of atrial size in the setting of chronic mitral regurgitation proved to be superior to standard two-dimensional techniques.