Electrophysiological and echocardiographic parameters predisposing to atrial fibrillation in patients with a structurally normal heart.
BACKGROUND
The electroanatomical substrate of dilated atria is characterised by increased non-uniform anisotropy and macroscopic slowing of conduction, which promote reentrant circuits.


OBJECTIVE
To analyse the relationship between electrophysiological properties of atria and echocardiographic markers of dilatation and increased filling pressure.


METHODS
The study group consisted of 79 patients without structural heart disease, aged 53+/-22 years, who were referred for electrophysiological study. In order to examine the atrial electrophysiological characteristics we studied interatrial conduction time (iaCT), double potentials and fragmented atrial activity during premature stimulation of the high right atrium (HRA). The analysed parameters included: duration of atrial activity, baseline iaCT (iaCTb) between HRA and distal coronary sinus (CS), iaCT during HRA pacing S1S1 600 ms (iaCTS1), maximum prolongation of iaCT during S2 and S3 delivery (iaCTS2, iaCTS3). We also calculated the decremental index (DI)=iaCT S3- iaCTS1/iaCTS1%. The following echocardiographic parameters were assessed: left atrial (LA) dimensions, surface (LAs), volume using ellipse formula (LAv), right surface (RAs), total atrial surface (TAs=LAs+RAs), and global myocardial index (GMI).


RESULTS
Patients were divided into two groups. Group 1 consisted of 37 patients with evidence of slow atrial conduction (atrial fragmentation/iaCTb>80 ms/DI>50%/double atrial potentials), whereas group 2 was composed of 42 patients without slow conduction properties. There were no significant differences concerning age, body mass index or LA parasternal dimensions between the groups. Thirty-seven patients, of whom 32 were from group 1, had documented episodes of paroxysmal atrial fibrillation. GMI, LAs, LAv and TAs values were significantly higher in patients from group 1 than in group 2 subjects. A statistically significant linear correlation between iaCTb and TAs (r=0.52 p <0.0001)/LAv (r=0.38 p <0.0001) was found. There was also a trend toward a correlation between DI and TAs.


CONCLUSIONS
This study supports the role of stretch and dilated atria in electrophysiological changes which occur in structurally normal hearts. The iaCT value may be indirectly and non-invasively evaluated using echocardiographic measurements.
Cozma
Dragos
D
Institute of Cardiovascular Medicine, Str. PP Carp nr. 13a, Timisoara, Romania. dragoscozmafr@yahoo.fr
Mornos
Cristian
C
Pescariu
Sorin
S
Petrescu
Lucian
L
Lighezan
Daniel
D
Dragulescu
Stefan-Iosif
SI
D016880:Anisotropy; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged