Prospective clinical evaluation of a programmed atrial stimulation protocol for induction of sustained atrial fibrillation and flutter

We sought to define a minimum standardized protocol for induction of atrial fibrillation [AF] and/or atrial flutter. In contrast to ventricular stimul ation protocols, a stimulation protocol for induction of AF or atrial flutt er 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 appr opriate electrical stimulation protocol for induction of AF or atrial flutt er We prospectively evaluated 70 patients, 44 with spontaneous atrial flutt er or AF and 26 controls without documented atrial arrhythmias. A standardi zed programmed stimulation protocol, which employed up to three atrial extr astimuli 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 fl utter and AF in 5 AF/atrial flutter patients (100%). Two patients with atri al flutter had both AF/atrial flutter and 1 patient with AF had atrial flut ter induced. The arrhythmia was induced from first stimulation site in 37 p atients (85%) using a single extrastimuli in 9 (20%) patients, double extra stimuli 18 (41%) patients and triple extrastimuli in 10 (23%) patients. Two patients (5%) required stimulation from second site with two and three ext rastimuli, respectively. The overall sensitivity and specificity of this st imulation protocol were 89% and 92%, respectively with a positive predictiv e accuracy of 95%. Conclusions. 1. Up to three atrial extrastimuli and two atrial sites are ne eded to increase yield of AF/atrial flutter induction at electrophysiologic study. 2. Induction of either AF or atrial flutter correlates well with th e presence of a similar spontaneous arrhythmia. 3. A baseline determination of the induction mode may be desirable prior to evaluation of intervention s directed at AF or atrial flutter.