title: Rapid atrial pacing does not decrease the atrial defibrillation threshold.
abstract: The aim of the study was to evaluate the effect of preshock atrial pacing on the atrial defibrillation threshold (DFT) during internal cardioversion of AF. The implantable atrial defibrillator has been added to the therapeutic options for patients with recurrent episodes of persistent AF. Although the device is efficient in restoring sinus rhythm, patient discomfort is a limitation. Methods that lower the ADFT are needed. Eleven patients with AF underwent internal cardioversion. In a randomized, crossover design, ADFT testing was performed, applying a step-up protocol starting at 100 V. Rapid atrial pacing was performed with a right atrial catheter for 20 seconds at 90% of the average cycle length of the fibrillatory waves and was immediately followed by a biphasic defibrillation shock. At each energy level, pacing + shock was compared to shock only, until the level at which sinus rhythm was restored by both modes. The step-up protocol was thereafter repeated using the inverse sequence of the two modes. A total of 19 ADFTs were obtained. For 10 the ADFT was lower with pacing + shock, in 4 equal and in 5 higher, than with shock only. The ADFT (mean +/- SD) with pacing + shock was 260 +/- 84 V(3.4 +/- 2.9 J) and did not differ from shock only: 268 +/- 85 V(3.8 +/- 3.0 J) (P > 0.05). The coefficient of variation and the coefficient of reproducibility for pacing + shock was 16% and 60 V, respectively, and for shock only 17% and 61 V. Rapid atrial pacing did not influence the internal ADFT in AF. The randomized, crossover protocol used was reproducible between different modes, and seems useful when testing the impact of different interventions on the ADFT.
authors.affiliation: Department of Cardiology, Karolinska Hospital, Stockholm Sweden. viveka.frykman@telia.com
authors.forename: Viveka
authors.initials: V
authors.lastname: Frykman
authors.forename: Borje
authors.initials: B
authors.lastname: Darpo
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Ayers
authors.forename: Lennart
authors.initials: L
authors.lastname: Bergfeldt
authors.forename: Cecilia
authors.initials: C
authors.lastname: Linde
authors.forename: Marten
authors.initials: M
authors.lastname: Rosenqvist
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018592:Cross-Over Studies; D017147:Defibrillators, Implantable / Q000009:adverse effects; D004554:Electric Countershock / Q000009:adverse effects / Q000379:methods*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method