Left Atrial P-Wave Analysis and Corresponding Invasively Measured Left Atrial Activation Time in a Patient With Extensive Low-Voltage Substrate
(A) Twelve-lead surface electrocardiogram of a representative patient with extensive left atrial (LA) low voltage. LA P-wave duration (LAP) is measured from the point of highest negative deflection (−dV/dt max) in lead V1 or V2 to the end of the P-wave in any of the leads (here 153 ms). Voltage mapping shows extensive low voltage of the left atrium both at 0.5-mV (B, C) and 1.0-mV (D, E) cutoffs. LA activation is importantly prolonged (LA activation time [LAT] 156 ms) to an extent that is comparable with LAP duration (F, G). Earliest activation of the left atrium in the septal region corresponds to −dV/dt max in lead V1 or V2 on surface electrocardiography (H).