- ECG criteria for atrial enlargement assumes sinus rhythm present
- No significant age-related differences for P wave amplitude to define RAE or LAE in children; therefore, apply adult RAE & LAE diagnostic criteria for all ages
Biatrial enlargement = RAE + LAE
- P wave amplitude:
- (1) >2.5 mm in II, or
- (2) Initial positive deflection >1.5 mm in V1 or V2
- Negative portion of P wave in V1: [depth (mm)] x [duration (s)] > -0.04 mm∙s
- Notched P waves in II with duration >95th percentile for age
- 95th percentile: birth, 65 ms; 12-16 y/o, 95 ms 
- Limited sensitivity (44%), but acceptable positive predictive value (85%) 
1. Liebman J. Atrial hypertrophy. In: Liebman J, Plonsey R, Gillette P (eds): Pediatric Electrocardiography. Baltimore, Williams & Wilkins, 1982, p 140.
2. Maok J, Krongrad E. Assessment of electrocardiographic criteria for left atrial enlargement in childhood. Am J Cardiol 53:215, 1984.