Left atrial size after cardioversion for atrial fibrillation: effect of external direct current shock.
OBJECTIVE
The aim of this study was to evaluate the effect of external direct current (DC) shock on left atrial (LA) dimension and volumes after cardioversion for atrial fibrillation, and the relation between LA size and atrial function.


METHODS
We evaluated 180 patients who were randomly cardioverted with DC shock (90 patients) or drugs (90 patients). Echocardiographic evaluations included LA size and volumes. LA passive and active emptying volumes were calculated, and LA function was measured as atrial ejection force. Changes in LA diameters and volumes were correlate with atrial systolic function.


RESULTS
The LA was dilated in all patients during arrhythmia and decreased after the restoration of sinus rhythm. The entity of reduction was different in the 2 groups of patients. LA maximal and minimal volumes were increased after DC shock as compared with patients treated with drugs (LA maximal volume 34 +/- 4 vs 31 +/- 5; P <.01; LA minimal volume 18 +/- 2.6 vs 15 +/- 3.6; P <.01). The atrial function was also depressed after DC shock and the delay in the recovery of atrial contractility was related to LA dilation. Patients treated with drugs had a higher atrial ejection force that was associated with a more marked reduction in LA maximal volume after the restoration of in sinus rhythm. A relationship between LA volumes and atrial ejection force was observed in the group of patients with depressed atrial mechanic function (r = -0.78; P <.001). The active emptying fraction was lower, although not significantly, in this group, whereas the conduit volume was increased.


CONCLUSIONS
External DC shock induced a depressed atrial mechanic function in many patients and this was associated with a persistence of LA dilation.
Mattioli
Anna Vittoria
AV
Department of Cardiology, University of Modena and Reggio Emilia, Italy. mattioli.annavittoria@unimo.it
Bonatti
Silvia
S
Bonetti
Lorenzo
L
Mattioli
Giorgio
G
D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy*; D016279:Atrial Function, Left / Q000187:drug effects / Q000502:physiology; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D004452:Echocardiography; D004554:Electric Countershock; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011342:Procainamide / Q000627:therapeutic use; D011405:Propafenone / Q000627:therapeutic use; D012008:Recurrence; D013223:Statistics as Topic; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D011405:Propafenone; D011342:Procainamide