Fractionated atrial electrograms during sinus rhythm: relationship to age, voltage, and conduction velocity.
BACKGROUND
Fractionated atrial electrograms (CFAEs) have been implicated in the mechanism of atrial fibrillation (AF). The prevalence and distribution of CFAEs in normal populations have not been clearly defined.


OBJECTIVE
This study sought to determine the influence of age on CFAEs and investigate the relationship between CFAEs and the underlying atrial substrate.


METHODS
Twenty-one patients without structural heart disease underwent electroanatomic mapping of their right atrium (RA). Patients were categorized into 3 groups according to age: group A, patients <30 years (25.1 +/- 3.1 years, n = 7); group B, patients between 31 and 59 years (51.7 +/- 10.3 years, n = 6); group C, patients >60 years (66.9 +/- 7.7 years, n = 8). The proportion of points with CFAEs was analyzed for the high and low septal RA, high and low lateral RA, and high and low posterior RA. The mean atrial voltage and conduction velocity were assessed in each of these regions.


RESULTS
The percentage of CFAEs was greater in group C (14.6% +/- 7.7%) than in group A (2.7% +/- 2.1%; P = 0.001). The percentage of CFAEs in group B (8.5% +/- 3.5%) was not significantly different from that in group A (P = 0.21) and group C (P = 0.14). The CFAEs were predominantly located in the posterior RA and high septal RA. There were significant correlations between the proportion of CFAEs and age (R = 0.72; P < 0.01), atrial voltage (R = -0.57; P < 0.01), and conduction velocity (R = -0.73; P < 0.001).


CONCLUSIONS
CFAEs increase with age and occur in regions of low atrial voltage and slowed conduction. The distribution of CFAE is predominantly along the posterior and high septal RA, regions where there are marked changes in myocardial fiber orientation. This suggests that the underlying myocardial architecture is the main influence on electrogram morphology.
Roberts-Thomson
Kurt C
KC
Department of Cardiology, Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia.
Kistler
Peter M
PM
Sanders
Prashanthan
P
Morton
Joseph B
JB
Haqqani
Haris M
HM
Stevenson
Irene
I
Vohra
Jitendra K
JK
Sparks
Paul B
PB
Kalman
Jonathan M
JM