The clinical course of multifocal atrial tachycardia in infants and children

Objectives This study outlines the clinical course, treatment and the late outcome of infants and children with multifocal atrial tachycardia (MAT). Background Multifocal atrial tachycardia is defined by three distinct P-wav eforms, irregular P-P intervals, isoelectric baseline between P-waves and r apid rate on an electrocardiogram. Several smaller prior reports have descr ibed pediatric patients with MAT, but their long-term outcome has not been fully assessed. Methods The clinical records, echocardiograms and long-term follow-up of pa tients with MAT were reviewed and compared to previous reports of MAT. Results Fourteen boys and seven girls (median age 1.8 months) presented wit h MAT. At diagnosis, six patients had respiratory illness, of whom two were critical. Ten were asymptomatic. Seven patients had structural heart disea se (SHD), one of whom died. Four of 15 patients (27%) with echocardiograms had diminished ventricular function. Ventricular rates were 111 to 253 beat s/min (mean 181 beats/min). Median duration of the arrhythmia was 4.9 month s (mean 6.7 months). Electrical cardioversion was attempted in 4 patients w ithout success and 15 patients received antiarrhythmic medication. Seventee n patients were followed for a mean of 60 months. Four patients were lost t o follow-up. There were no late arrhythmias. Conclusions The majority of children with MAT are healthy infants under one year of age; a feud may exhibit mild to life-threatening cardiorespiratory disease. Less often, MAT accompanies SHD. Mild ventricular dysfunction may be observed in the presence of MAT, but symptoms are few and resolution is generally complete. Response to antiarrhythmic agents is mixed, and cardio version is of no avail. Finally, long-term cardiovascular and developmental outcome depends principally on underlying condition; for otherwise healthy children, it is excellent. (J Am Coll Cardiol 2001;38:401-8) (C) 2001 by t he American College of Cardiology.