Inducibility of atrial fibrillation in the absence of atrial fibrillation: what does it mean to be normal?
BACKGROUND
While inducibility of atrial fibrillation (AF) is often used as an endpoint for radiofrequency ablation of AF, little is known regarding inducibility among normals. We therefore evaluated the inducibility of AF with rapid atrial pacing in patients without a clinical history of AF after catheter ablation of supraventricular tachycardia (SVT).


METHODS
We prospectively evaluated 86 patients with no history of AF who were referred for catheter ablation of SVT. After successful ablation, two different rapid atrial pacing protocols for induction of AF were tested. First, AF induction was attempted by 5-second bursts of atrial pacing from the coronary sinus ostium (CSO) at three different cycle lengths (CLs). Next, decremental pacing was performed from the CSO starting at a CL of 250 ms to the loss of 1:1 atrial capture. This protocol was repeated 3 times for each subject.


RESULTS
Three of the subjects (3.5%) enrolled had inducible AF with the first pacing protocol. However, with the second protocol, AF was inducible in 22 patients (25.6%), including sustained AF in 16 patients (18.6%). There were significant differences in the inducibility of AF between the two atrial pacing protocols. Additionally, with the second pacing protocol, patients with a loss of 1:1 atrial capture at CL <180 ms were more easily inducible for AF (21/63 vs. 1/23; P = .006).


CONCLUSIONS
Using a specific, decremental pacing protocol, 26% of patients without a history of AF had inducible AF. These findings suggest that significant further investigation is needed to optimize the specificity of using AF induction as an endpoint for AF ablation.
Clinical Electrophysiology Laboratory and Arrhythmia Center, Fu Wai Hospital and Cardiovascular Institute, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
Wen
W
Huang
Tong
T
Liu
Michael
M
Shehata
Kuijun
K
Zhang
Yan
Y
Yao
Guodong
G
Niu
Allen
A
Amorn
Xiushi
X
Liu
Sumeet S
SS
Chugh
Xunzhang
X
Wang
D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence