Atrial Tachycardia In Children:Clinical Characteristics,Management,Follow-Up And Early Identification Of Tachycardia Induced Myocardial Damage

Atrial tachycardia(AT) is a common type of supraventricular tachycardia in pediatric population, and it can be resistant to antiarrhythmic drugs and lead to tachycardia induced cardiomyopathy(TIC) if not properly managed. The study aimed to characterize the natural history and response to treatment of AT in children, assess the risk factors for the development of TIC secondary to AT in children, determinate the diagnostic ability of Tissue Doppler imaging(TDI) for identifying initial cardiac dysfunction of children with AT. From January 2009 through April 2014, 144 children(78 girls and 66 boys); median age 5.13±4.31 years(range 0.08 to 16.33 years) were admitted to our hospital with a diagnosis of AT. We examined the clinical detailed history, 12 lead ECG, 24-h Holter recording, response to therapy and follow-up of the children. Cardiac function was evaluated by conventional echocardiography, TDI, and plasma N-terminal pro-brain natriuretic peptide(NT-proBNP). Various clinical factors such as age, sex, duration time, the presence of atrial rhythm in Holter monitoring, ventricular rate of AT, the type of AT and cardiac function were compared between two groups of children with or without TIC, among children with different responses to antiarrhythmic drugs(control, partial control, ineffective). Doppler signals were compared between two groups of children with normal or elevated plasma NT-proBNP concentrations. The AT characteristics associated significantly with the development of TIC and well response to antiarrhythmic medications in children were analyzed.The study found that the onset of AT occurred at any age with a distribution with positive skewness, and the onset of AT was not uncommon in fetus period. Children with AT presented with a variety of non-specific symptoms, and the digestive tract symptoms including vomiting, bellyache and feeding problem were common. Incessant AT comprised a greater percentage as high as 36.1%. Control of AT on antiarrhythmic drugs was achieved in 102 of 115(88.7%) of the children, the combination of sotalol and propafenone showed good effectiveness in the study for control of children with AT. Acute success of radiofrequency ablation(RFA) in children who performed poor response to antiarrhythmic drugs was achieved in 45 of 49(91.8%), recurrences were frequently located in atrial appendage sites. Children in the control group who were younger at diagnosis(mean age 2.63±3.54 years vs. 4.98±3.95 years, p<0.05) had a shorter duration time(mean time 0.86±1.39 years vs. 2.41±2.48 years, p<0.01) and lower percentage of incessant tachycardia(27.6% vs. 64.5%, p<0.01) compared with children who displayed poor response to medications therapy. Sotalol was significantly associated with control of AT in children, compared to other antiarrhythmic drugs. The incidence of TIC secondary to AT was 18.1%, and AT in children with TIC was associated with a high incidence of incessant tachycardia(92.3%). The incidence of TIC in patients presenting incessant tachycardia was significantly higher than that of patients presenting paroxysmal tachycardia(46.1% vs. 2.6%, p<0.01). After successful control of tachycardia, left ventricular ejection fraction(LVEF) of patients with TIC gradually recovered within 2 to 94 days. Compared with LVEF, the TDI-MPI and E/E? showed better correlations with elevated NT-proBNP. Addition of TDI-MPI and E/E? to LVEF provided increased information to detect elevated NT-proBNP(91.7% sensitivity).We can conclude from the study that AT in children predominantly occurred in young infants and children with non-specific symptoms and went unrecognized. Incessant AT comprised a greater percentage as high as 36.1% and resulted in TIC frequently. The combination of sotalol and propafenone is highly efficacious in the treatment of AT in children. Independent factors associated with well response to pharmacological therapy include younger age at diagnosis, nonincessant tachycardia and shorter duration time in children with AT. RFA should be considered as a preferred treatment for children who displayed poor response to medical therapy. TIC occurs in 18.1% of children with AT and is reversible. The development of TIC secondary to AT in children is incessant tachycardia-dependent. The TDI-MPI and E/E? may be more powerful predictors of initial LV dysfunction over conventional echocardiography in pediatric population with AT.