Global left atrial dysfunction and regional heterogeneity in primary chronic mitral insufficiency

We assessed the hypothesis that global and regional left atrial (LA) function is altered in patients with chronic primary mitral regurgitation (MR) secondary to myxomatous mitral valve disease (MMVD).

Velocity vector imaging of the LA was acquired from apical four- and two-chamber views in 41 normal and 43 subjects with chronic MR due to MMVD. All had normal left ventricular systolic function. The LA subendocardium was traced to obtain atrial volumes, ejection fraction, velocities, and strain (ε)/strain rate (SR) measurements. To explore the effects of MR severity on LA function, subjects were divided into two groups: mild vs. moderate/severe MR. Reservoir (expansion and diastolic emptying indices), booster pump (active emptying index) functions, and LA ejection fraction were markedly impaired in subjects with MR (P < 0.001). Mean LA ε was reduced in moderate/severe MR compared with control subjects (P < 0.01). A consistent pattern of differences in atrial regional function was noted with the anterior wall having a lower peak systolic ε/SR, which is more evident in the moderate/severe MR group (P < 0.01) when compared with controls and mild MR groups.

LA filling during ventricular systole (reservoir function), LA contraction (booster pump function), and ejection fraction were significantly impaired in patients with chronic MR. Regional differences in LA contractility at the anterior wall were noted presumably due to the eccentricity of the systolic anteriorly directed MR jet hitting the anterior wall and altering local wall mechanics.