[Characteristics of paroxysmal atrial tachycardia in infants according to the age of onset].

Seventy consecutive patients hospitalized before 1 year of age for reentrant paroxysmal atrial tachycardia (PAT) were studied according to the age of onset of arrhythmia making 3 distinctive groups: group I: 10 patients in whom onset of the arrhythmia occurred during foetal life; group II: 39 infants whose arrhythmia appeared during the first month of life and group III consisting of 21 patients in whom tachycardia began between 1 and 12 months of age. The characteristics and the consequences of the arrhythmia as well as the patients' course and the different treatments used were analysed. Foetal tachycardias were characterized by a slower heart rate. Episodes were most often short and repetitive as opposed to post-natal tachycardias which were often prolonged but somewhat unfrequent. Before the age of 3 months the occurrence of heart failure was more frequent. Independently of the age of onset, 43% of patients presented Wolff-Parkinson-White syndrome (WPW), which disappeared spontaneously in 1 out of 3 cases. The existence of WPW syndrome was correlated with late relapses.