Changes in atrial electrical properties following cardioversion of chronic atrial fibrillation: relation with recurrence.
OBJECTIVE
To study the reversibility of atrial electrical remodeling and its relation with recurrence in post-conversion chronic atrial fibrillation (CAF) patients.


METHODS
In 28 drug-free CAF patients (mean AF duration 41+/-39 months) electrically converted to sinus rhythm effective refractory period (ERP) at 500 ms, monophasic action potential at 90% of repolarization (MAPd90) at five cycle lengths (CL, 350, 400, 450, 500, 600 ms), and P wave duration were measured three times: within the interval 5-20 min post-conversion, 24 h and 1 month later. Fifteen subjects with no history of AF and normal atrial structure served as a control group. Patients were followed up for recurrence for 1 month; 12 relapsed.


RESULTS
ERP changed from 205+/-20 to 243+/-31 to 241+/-24 ms (P<0. 001), attaining a level comparable to that of the controls (238+/-21 ms) within 24 h. MAPd90 significantly (P<0.001) increased (from 175+/-11 to 190+/-19 to 191+/-10 ms at CL 350 ms and 201+/-12 to 234+/-20 and 233+/-23 ms at CL 600 ms) also reaching control levels within 24 h. MAPd90 exhibited an abnormal adaptation to rate only in the first evaluation. P wave duration was prolonged (137+/-33 ms) and exhibited a slower course of shortening (130+/-32 to 123+/-27 ms, P<0.001), reaching control levels within 1 month. Patients with higher values of MAPd90 at CL 350 in the immediate post-conversion period were more likely to relapse (P<0.005).


CONCLUSIONS
ERP and repolarization shortening as a result of CAF are reversed within 24 h after conversion, while P wave duration reduces more slowly. Post-conversion MAPd90 values contain prognostic information for recurrence.
Manios
E G
EG
Department of Cardiology, University Hospital of Heraklion, Crete, Heraklion, Greece.
Kanoupakis
E M
EM
Chlouverakis
G I
GI
Kaleboubas
M D
MD
Mavrakis
H E
HE
Vardas
P E
PE
D000200:Action Potentials; D000368:Aged; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002908:Chronic Disease; D003627:Data Interpretation, Statistical; D004554:Electric Countershock; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence