Left atrial systolic force in asymptomatic aortic stenosis.

BACKGROUND

There is a limited knowledge about left atrial (LA) systolic force (LASF) and its key determinants in patients with asymptomatic mild-moderate aortic stenosis (AS).

METHODS

We used baseline clinic and echocardiographic data from 1,566 patients recruited in the simvastatin ezetimibe in aortic stenosis study evaluating the effect of placebo-controlled combined simvastatin and ezetimibe treatment in asymptomatic AS. The LASF was calculated by Manning's method. Low and high LASF were defined as <5th and >95th percentile of the distribution within the study population, respectively.

RESULTS

Mean LASF in the total study population was 21±14 kdynes/cm2. The determinants of LASF were higher age, heart rate, body mass index, systolic blood pressure, left ventricular (LV) mass, mitral peak early velocity, maximal LA volume, and longer mitral deceleration time (multiple R2=0.37, P<0.01). High LASF (78 patients) was characterized by abnormal LV relaxation in 90% of the cases. Low LASF (82 patients) was associated with restrictive LV filling pattern, absence of abnormal relaxation pattern, smaller maximal LA volume, and lower body mass index. In 40% of the patients with low LASF, estimated LV filling pressures were normal and the reduced LA force was explainable by an intrinsic systolic LA dysfunction.

CONCLUSIONS

In patients with asymptomatic AS, LASF was closely related to filling pressure. Higher LASF invariably signifies the maximal LA effort to keep near normal LV filling pressure; lower LASF belongs to a heterogeneous group of patients in which it is much more difficult to depict who have low LA preload or who have intrinsic systolic LA dysfunction.