Return of atrial mechanical function following electrical conversion of atrial dysrhythmias.

The return of atrial mechanical function and its relationship to embolic events following cardioversion of atrial arrhythmias is controversial. Fourteen patients with atrial arrhythmias were evaluated with pulsed Doppler echocardiography before and after direct current (DC) cardioversion. The atrial filling fraction increased significantly: 1.14 +/- 4.3% at baseline versus 14.9 +/- 13.3%, 13.4 +/- 11.4%, and 21.9 +/- 13.5% at 5 minutes, 30 minutes, and 24 hours, respectively, following cardioversion. Absent atrial mechanical activity was noted in four patients immediately after cardioversion. Mechanical activity resumed by 30 minutes in one patient and at 24 hours in two others. Those with delayed atrial function had lower stroke volumes and atrial filling fractions following cardioversion. An embolic event occurred in one patient who had immediate return of atrial mechanical activity. This patient also had the largest atrial filling fraction of any patient at 24 hours (41%). These data suggest that the degree of atrial mechanical activity following cardioversion is variable and that embolic episodes are not necessarily related to delayed return of atrial mechanical activity following cardioversion.