Atrial tachycardia in infants and children: electrocardiographic classification and its significance.

An electrocardiographic classification of atrial tachycardia and its significance in children has not been reported. We reviewed the clinical histories and 12-lead surface electro-cardiograms (ECG) of 21 children with atrial tachycardia. Atrial rate and P-wave axis were determined for each patient. Some patients had features of typical atrial flutter (AF). Tachycardia was classified by atrial rate < 340/min or atrial rate > 340/min. Children with atrial tachycardia rate > 340/min consistently responded to conservative treatment (digoxin and/or cardioversion) without recurrences (p < 0.05 and p > 0.025); whereas in children with atrial rate < 340/min, only one case responded to conservative therapy. P-wave axis had no prognostic significance for either group. Additionally, high atrial rate (> 340/min) during tachycardia was noted in early infancy, compared to older children and adults, and probably represents the function of age. Classification of atrial tachycardia by rate is clinically useful for planning therapy and predicting response in children.