Prediction of incipient left ventricular dysfunction in patients with chronic primary mitral regurgitation: a velocity vector imaging study

Abstract

Progressive left ventricular (LV) dilatation and irreversible myocardial damage are important causes of morbidity and mortality in patients with chronic primary mitral regurgitation (MR) due to myxomatous mitral valve disease. We assessed the hypothesis that early subclinical LV dysfunction secondary to chronic primary MR could be signalled by abnormal LV rotation mechanics, utilizing velocity vector imaging (VVI). Forty-three with chronic primary MR and 41 normal subjects were evaluated. All had normal LV systolic function. Peak endocardial and epicardial rotations in systole were measured in apical and basal short-axis images. LV twist was defined as the net difference between apical and basal angles of rotation while LV torsion was calculated as LV twist divided by LV diastolic longitudinal length. To explore the effects of MR severity on LV rotation, patients were divided into three groups: mild, moderate, and severe MR. The peak twist and torsion of the LV endocardium displayed significant differences across the study groups (P = 0.005 and 0.015, respectively). Subjects with moderate MR revealed the highest LV rotation profile (2.26 ± 0.66°/cm and 17.83 ± 5.2° for torsion and twist, respectively), implicating hyperdynamic LV function. However, severe MR group showed the lowest LV rotation profile (1.39 ± 0.8°/cm and 11.43 ± 6.09° for torsion and twist, respectively), suggesting incipient LV dysfunction. There were no significant differences in epicardial LV rotations. Evaluation of global LV function by VVI is a novel reproducible index for detecting subnormal latent LV dysfunction in chronic MR patients, which may aid in the optimal timing of surgery.