Factors of Tachycardia-Induced Cardiomyopathy in Children

Materials and Methods: A total of 158 children with idiopathic arrhythmias aged 0 to 7 years were examined. Nosological groups of arrhythmias included WPW syndrome (n=82), atrial ectopic tachycardias (n=44), atrial flutter (n=11), AV reentry junctional tachycardias (n=7), and ventricular tachycardias (n=13). Age groups comprised infants (n=73), 1–3-year-old children (n=43), and 3–7-year-old children (n=98).

Results: The predominant types of arrhythmias were paroxysmal tachycardias in 3–7-year-old children (χ2=11.077, p=0.001) and incessant tachycardias in infants (χ2=13.030, p<0.001). The frequency of paroxysmal tachycardia episodes was higher in infants compared with 1–3-year-old (p=0.028) and 3–7-year-old children (p<0.001). Based on the echocardiography findings, signs of tachycardia-induced cardiomyopathy found more often in older children compared with the younger patients (χ2=12.312, p=0.002). On the contrary, the presence of heart failure was more typical for infants than for 1- to 7-year-old patients (F=44.117; p=<0.001).

Conclusions: Arrhythmogenic heart remodeling occurred more frequently in children aged 3 to 7 years. Clinical signs of heart failure in infants with arrhythmias preceded structural changes and functional abnormalities in the intracardiac hemodynamics indices. The preservation of normal sizes of cardiac chambers in the presence of high heart rates probably resulted in the diastolic dysfunction in infants. The factors leading to these hemodynamic changes were the high average daily heart rate, tendency of tachycardia to permanent and continuously recurring course, and high frequency of paroxysmal tachycardia episodes in infants.