Electrocardiographic and vectorcardiographic study of interatrial conduction disturbances with left atrial retrograde activation.

From 81,000 ECGs we collected 83 cases that fulfilled the criteria of Interatrial Conduction Disturbances with Left Atrial Retrograde Activation (IACD-LARA) (P +/- in II, III and VF with P width greater than or equal to 120 msec.). We present the detailed study of 35 cases with surface ECG and VCG and 29 cases with orthogonal ECG leads. The results are then compared against two control groups: with cardiopathy (30 cases) and without cardiopathy (25 cases). The prevalence of IACD-LARA was nearly 1% globally, and 2% among patients with valvular heart disease. The diagnostic criteria for IACD-LARA are: 1) ECG: P +/- in II, III and VF with P greater than or equal to 120 msec. with open angle (usually greater than 90 degrees) between the first and the second part of the P.2) Orthogonal ECG: P +/- in Y lead with a negative mode greater than 40 msec. 3) VCG: More than 50 msec. above the X or Z axis, duration of the P loop greater than or equal to 110 msec., open angle between the two parts of the P loop in both frontal (131.3 degrees +/- 32.3) and right sagital planes (171.2 degrees +/- 15.1), and presence of notches and slurrings in the last part of the P loop.