Abstract

Objective: To measure the distance between the mitral leaflet coaptation point and the mitral annulus (CPMA) and assess the relation of this index to structural and functional characteristics of the failing left ventricle.

Design: Echocardiographic indices and CPMA were measured at baseline and again during dobutamine infusion and leg lifting. Left ventricular diastolic and systolic dimensions, left ventricular ejection fraction (LVEF) by Simpson’s rule, mitral annulus dimension, and E point septal separation were correlated with CPMA.

Setting: Tertiary referral centre.

Patients: The total study population of 129 patients included 94 with LVEF < 35% and 35 with LVEF 35%–45%; 76 had coronary artery disease and 53 had dilated cardiomyopathy.

Interventions: A dobutamine infusion was given in 18 patients and preload increase by leg lifting in 28.

Main outcome measures: Correlations between CPMA and contractility indices at baseline and during interventions.

Results: CPMA was correlated with left ventricular diastolic dimension (r = 0.52), left ventricular systolic dimension (r = 0.53), LVEF (r = −0.44), fractional shortening (r = −0.42), E point septal separation (r = 0.48), and mitral annulus dimension (r = 0.44) (all p < 0.001). Dobutamine decreased CPMA from (mean (SD)) 12.04 (3.64) mm to 8.92 (2.56) mm and increased LVEF from 27 (6.2)% at baseline to 33.4 (6.9)% at 10 μg/kg/min (both p < 0.001). These changes were strongly related (r = 0.68, p < 0.007). After leg lifting, CPMA decreased from 13 (4) mm at baseline to 10 (3) mm (p < 0.001), and LVEF increased from 32 (11)% at baseline to 39 (11)% (p < 0.001). Fractional shortening and left ventricular diastolic dimension also increased (p < 0.001) and mitral annulus dimension and E point septal separation decreased (p < 0.002), but left ventricular systolic dimension did not change.

Conclusions: The mechanism displacing the mitral coaptation point towards the left ventricular apex is multifactorial. The correlations between CPMA difference (before versus after interventions) and ejection fraction difference (before versus after interventions) shows that this index depends mainly on left ventricular function.