Atrial stimulation protocols to test inducibility of atrial fibrillation

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: The electrophysiological inducibility of atrial fibrillation (AF) after pulmonary vein isolation (PVI) has been identified as a predictor of future AF recurrence. Stimulation protocols have not been sufficiently studied prospectively with respect to their reliability for inducing AF. METHODS AND RESULTS: We conducted a prospective monocentric randomized clinical trial to evaluate different standardized electrical stimulation protocols on their potential to induce AF. Patients with symptomatic AF presenting in sinus rhythm scheduled for PVI were enrolled. The primary outcome was induction of AF. A total of 30 patients (age=62±2 years, 17% female, 13% persistent AF, left atrial systolic volume (LASV) 93±5 ml) were enrolled and randomized. To one of three different stimulation protocols performed at the beginning of PVI. Atrial fibrillation was induced in 4 out of 10 patients (40%) with fixed cycle length stimulation followed by up to 3 extrastimuli (protocol A), 6 out of 10 patients (60%) with burst stimulation (protocol B) and 9 out of 10 patients (90%) with fixed stimulation using the shortest cycle length with 1:1 atrial capture (protocol C), respectively. Time from start of stimulation to inducibility of AF was significantly lower in protocol C vs. protocol B and A (29±10 sec vs 40±14 sec vs 366±71 sec; p<0.0001). Isoprenaline was used in 10% in protocol A, 40% in protocol B and 80% protocol C. Overall, there were no significant differences concerning age (61±3 vs. 63±4 years; p=0.74), LASV (93±6 vs. 94±8 ml; p=0.98) or other parameters between patients with inducible and non-inducible AF. CONCLUSION: With systematic stimulation protocols AF can be induced in up to 90%. Further studies are warranted to assess the specifity of these stimulations.