Atrial ejection force: a noninvasive assessment of atrial systolic function

The purpose of this study was to define atrial ejection force and to develop a method for its noninvasive measurement from echocardiographic data.

Assessment of diastolic function through measurement of the components of ventricular filling has largely neglected the vigor of atrial systole, in part because this has been difficult to quantify. However, atrial ejection force, defined as that force exerted by the left atrium to accelerate blood into the left ventricle during atrial systole, can be assessed noninvasively by combined two-dimensional imaging and Doppler echocardiography. This index of atrial function, based on classic newtonian mechanics, provides a physiologic assessment of atrial systolic function.

To evaluate the usefulness of atrial ejection force, we studied the return of left atrial ejection force in 29 patients after elective cardioversion for atrial fibrillation. Transmitral Doppler inflow patterns at rest were assessed immediately after cardioversion and at 24 h, 1 week, 1 month and > 3 months later. A healthy adult group (n = 10) served as control subjects.

After successful cardioversion, atrial ejection force was significantly depressed compared with that in the control group (5.2 +/- 6.8 vs. 16.3 +/- 4.7 kdynes; p < 0.0001). Over successive weeks, atrial ejection force improved in the subgroup of patients who remained in sinus rhythm (n = 18), whereas no improvement was seen during the period of maintained sinus rhythm in the patients with subsequent reversion to atrial fibrillation (n = 11).

Atrial ejection force provides a physiologic assessment of atrial systolic function and is a potentially useful index for assessing atrial contribution to diastolic performance. In patients who successfully underwent cardioversion from atrial fibrillation, atrial ejection force improved over several weeks only in the subgroup in which sinus rhythm was maintained.