CLINICAL RESEARCH: CARDIAC RHYTHM DISORDER
Separating Atrial Flutter From Atrial Fibrillation With Apparent Electrocardiographic Organization Using Dominant and Narrow F-Wave Spectra
Bobbi L. Hoppe, MD,
Andrew M. Kahn, MD, PhD,
Gregory K. Feld, MD, FACC,
Alborz Hassankhani, MD, PhD and
Sanjiv M. Narayan, MB, MD, FACC*
Electrophysiology Service, Veterans Affairs San Diego, University of California San Diego, San Diego, California.
Manuscript received June 2, 2005;
revised manuscript received July 1, 2005,
accepted August 8, 2005.
* Reprint requests and correspondence: Dr. Sanjiv M. Narayan, Director, Electrophysiology Service, VA San Diego, University of California San Diego, Box 111A, 3350 La Jolla Village Drive, San Diego, California 92161. (Email: snarayan{at}ucsd.edu).
OBJECTIVES: The purpose of this study was to separate atrial flutter (AFL) with atypical F waves from fibrillation (AF) with "apparent organization."
BACKGROUND: We hypothesized that F-wave spectra should reveal a dominant and narrow peak in AFL, reflecting its single macrore-entrant wave front, but broad spectra in AF, reflecting multiple wave fronts.
METHODS: We identified 39 patients with electrocardiograms (ECGs) of "AFL/AF" or "coarse AF" from 134 consecutive patients referred for ablation: 21 had AFL (18 atypical, 3 typical), 18 had AF, and all were successfully ablated. Filtered atrial ECGs were created by cross-correlating F waves to successive ECG time points. Dominant peaks between 3 and 10 Hz were identified from power spectra of X (lead V5), Y (aVF), and Z (V1) axes, and for each, we calculated height (relative to two adjacent spectral points) and area ratio to envelopes of bandwidth 0.625, 1.25, 2.5, 3.75, and 5 Hz (range 0 to 1, where higher ratios reflect narrower peaks).
RESULTS: Dominant peaks had greater relative height for AFL than AF (three-axis mean: 14.2 ± 6.4 dB vs. 6.6 ± 2.1 dB; p < 0.001). Peak area ratios were also higher for AFL than AF for all envelopes (p < 0.001). For the 2.5-Hz envelope, the separation (0.61 ± 0.14 vs. 0.35 ± 0.05, respectively; p < 0.001) enabled a ratio 0.44 to identify all cases of AFL from AF (p < 0.001). A panel of seven cardiologists blinded to clinical data provided lower diagnostic accuracy (82.1%; p < 0.01).
CONCLUSIONS: In ambiguous ECGs with atypical F waves, spectral evidence for a solitary activation cycle separates AFL from AF with "apparent organization." This approach might improve bedside ECG diagnosis and shed light on intra-atrial organization of both rhythms.
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Abbreviations and Acronyms
| | AF = atrial fibrillation | | AFL = atrial flutter | | CL = cycle length | | CTI = cavotricuspid isthmus | | ECG = electrocardiogram/electrocardiography | | EPS = electrophysiologic study | | LA = left atrium | | PV = pulmonary vein | | RA = right atrium | | ROC = receiver-operating characteristic |
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