Electrocardiographic Measurements of Regional Atrial Fibrillation Cycle Length

BACKGROUND: Differences in atrial fibrillation (AF) cycle length (CL) between the left (LA) and right (RA) atrium and coronary sinus (CS) may help separate paroxysmal from persistent AF and identify patients most likely to respond to pulmonary vein isolation, but has not been measured noninvasively. METHODS AND RESULTS: We developed methods to estimate regional intraatrial AF CL from the surface electrocardiogram (ECG) in 20 patients with persistent AF and 10 patients with paroxysmal AF prior to ablation. Intraatrial AF CL was measured near the LA appendage, mid-CS, and lateral RA. In simultaneous filtered ECG, AF CL was estimated using autocorrelation. The mean of ECG-derived AF CL in leads V5, I, and aVL was used to estimate LA CL; leads aVF, II, and III for CS CL; and V1, V2, and aVR for RA CL. ECG CL estimates for the LA, CS, and RA had R(2) > 0.91 versus measured CL (all P < 0.001). Though magnitudes of left-versus-right AF CL gradients were small in this series, the ECG predicted the direction of gradients in 62% of measurements (P < 0.05). When the gradient was >10 ms, the direction was accurately predicted in eight of 11 patients. The accuracy of AF CL estimates was not adversely affected by AF type or LA dilatation (< or =40 or >40 mm). The ECG-estimated AF-CL showed high 5-minute temporal stability (P < 0.001 each chamber). CONCLUSIONS: Left and right atrial AF CL, and their gradients, can be accurately determined from the ECG using autocorrelation analysis. This approach may be a helpful guide prior to ablation procedures.