Does Synthesized Lead V9 Reflect Left Atrial Activity During Atrial Fibrillation

Previous studies have demonstrated right-sided precordial leads could reflect mostly right atrial (RA) activity, while posterior lead V9 could reflect mostly left atrial (LA) activity. 18 synthesized lead ECG enables us to extrapolate posterior leads V7-9 and right- sided precordial leads (V3R-V5R). Therefore, we conducted a preliminary study on whether synthesized leads are able to evaluate both atrial activities during atrial fibrillation. We recorded the standard 12-lead ECG, posterior leads V7-V9, right-sided precordial leads V3R-V5R and intracardiac electrograms (EGM) in the RA, LA and coronary sinus (CS) simultaneously from 1 male subject with paroxysmal AF before pulmonary vein isolation. The corresponding dominant frequency (DF) was estimated from the peak frequency of each lead's fibrillatory wave or EGM's FFT. The DFs in LA from EGMs in CS and LA (5.1 and 5.1 Hz) were consistent with that in lead V9 (5.1 Hz). Furthermore, that in synthesized lead V9 showed a close value (5.0 Hz). Furthermore, the DF in intracardiac RA (4.8 Hz) was close to that in V1 (4.8 Hz) and V3R-V5R. Synthesize lead V9 may evaluate the LA activity, and help in monitoring AF and identifying ablation sites through combining with the standard 12-lead ECG.