Prospective clinical evaluation of a programmed atrial stimulation protocol for induction of sustained atrial...

We sought to define a minimum standardized protocol for induction of atrial fibrillation [AF] and/or atrial flutter. In contrast to ventricular stimulation protocols, a stimulation protocol for induction of AF or atrial flutter has not been critically evaluated. Since suppression of inducible AF or atrial flutter is used as one of the endpoints of success of pharmacologic and ablation therapies, there is an obvious need to define a minimally appropriate electrical stimulation protocol for induction of AF or atrial flutter. We prospectively evaluated 70 patients, 44 with spontaneous atrial flutter or AF and 26 controls without documented atrial arrhythmias. A standardized programmed stimulation protocol, which employed up to three atrial extrastimuli delivered at two atrial sites at two atrial drive pacing lengths, was used in attempt to reproduce sustained AF and atrial flutter. The study endpoint was induction of sustained (> 30 s) AF or atrial flutter. Sustained AF or atrial flutter was induced in 39/44 (89%) patients and 2/26 (7%) of controls (p < 0.01). The arrhythmia induced was atrial flutter in 19/21 (91%) of atrial flutter patients, AF in 17/18 (94%) AF patients, both atrial flutter and AF in 5 AF/atrial flutter patients (100%). Two patients with atrial flutter had both AF/atrial flutter and 1 patient with AF had atrial flutter induced. The arrhythmia was induced from first stimulation site in 37 patients (85%) using a single extrastimuli in 9 (20%) patients, double extrastimuli 18 (41%) patients and triple extrastimuli in 10 (23%) patients. Two patients (5%) required stimulation from second site with two and three extrastimuli, respectively. The overall sensitivity and specificity of this stimulation protocol were 89% and 92%, respectively with a positive predictive accuracy of 95%.

1. Up to three atrial extrastimuli and two atrial sites are needed to increase yield of AF/atrial flutter induction at electrophysiologic study. 2. Induction of either AF or atrial flutter correlates well with the presence of a similar spontaneous arrhythmia. 3. A baseline determination of the induction mode may be desirable prior to evaluation of interventions directed at AF or atrial flutter.