Alternans of atrial action potentials during atrial flutter as a precursor to atrial fibrillation

• Published in: Circulation (New York, N.Y.) N.Y.), 2002-10, Vol.106 (15), p.1968-1973
• Main Authors: NARAYAN, Sanjiv M, BODE, Frank, KARASIK, Pamela L, FRANZ, Michael R
• Format: Article
• Language: English
• Subjects: Action Potentials; Aged; Atrial Fibrillation - etiology; Atrial Flutter - complications; Atrial Flutter - physiopathology; Biological and medical sciences; Cardiac dysrhythmias; Cardiology. Vascular system; Heart; Heart Atria - physiopathology; Humans; Kinetics; Male; Medical sciences; Ventricular Fibrillation - etiology
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.0000037062.35762.B4

The mechanisms underlying the transition of typical atrial flutter (Afl) to fibrillation (AF) remain unclear. We set out to test the hypothesis that Afl disorganizes to AF via alternans of atrial action potentials. In 38 patients with Afl, monophasic action potentials (MAPs) were recorded at the isthmus and either high or low right atrium (HRA, LRA) during overdrive pacing to 160 ms or to the initiation of AF, whichever came first. MAP duration measured at 90% repolarization was longer at the isthmus in all patients, and failed to shorten with rate, compared with the HRA (n=38) or LRA (n=5). In 20 patients who developed AF, progressive pacing first caused alternans of isthmus MAP duration and amplitude at mean cycle length of 219+/-45 ms, followed by AF at a mean onset cycle length of 184+/-38 ms. Subsets of this group showed spontaneous action potential duration alternans at the isthmus (11 of 20 patients) and 2:1 isthmus conduction block immediately preceding AF (4 of 20 patients). In the 18 patients who did not develop AF, MAP alternans was less common (9 of 18 patients; P