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Few clinical indices identify propensity to atrial fibrillation (AF) during sinus rhythm. Repolarization alternans has been shown to indicate AF vulnerability, but is limited by the sensitivity to detect changes in action potential duration (APD), that may be subtle. We hypothesized that spectral analysis would be a more sensitive and robust marker of AP alternans and thus a better clinical index of individual propensity to AF than APD alternans.
In 30 patients (27 AF patients, 3 controls with no AF), we recorded left (n=26) and right (n=6) atrial APs during incremental pacing from cycle length (CL) 500ms (120bpm) to AF onset (Fig A). Alternans was measured by APD (Fig A-B) and spectral analysis (Fig C-D).
At baseline (CL 490±28ms), APD alternans was detected in only 7/27 AF patients, while spectral AP alternans was detected in 21/27 AF patients (p<0.001). Neither APD alternans nor spectral alternans were present in control patients at baseline. Spectral AP alternans prevalence and magnitude increased with rate acceleration in AF patients, and was undetectable in controls, rising just before induced AF.
Spectral AP alternans at baseline can identify patients with, versus those without, clinical histories and pathophysiological substrates for AF. Future studies should examine whether the presence of spectral AP alternans during sinus rhythm may obviate the need to actually demonstrate AF, such as on ambulatory ECG monitoring.
Poster Sessions, Expo North
Monday, March 11, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Arrhythmias: AF/SVT X
Abstract Category: 4. Arrhythmias: AF/SVT
Presentation Number: 1279-45
- 2013 American College of Cardiology Foundation