Medical study in which the efficacy of anti-arrhythmic drugs on ventricular ectopic heartbeats in children will be examined

INTERVENTION: In a pediatric cohort of patients the acute effect of beta‐blocker vs flecainide on the amount of PVCs will be tested in an open label cross‐over design. After baseline function testing patients will be randomized to first receive an oral dose of metoprolol (1 mg/kg/dose twice daily) and secondly flecainide (2 mg/kg/dose twice daily) or the other way around. Each drug will be administered for at least 5 consecutive days, after which function testing will be repeated. In between a drug free period of at least two weeks will be implemented, to allow complete clearance of the drug. CONDITION: Children, Antiarrhythmic drugs , Left ventricular function ; ; PRIMARY OUTCOME: The acute effect of flecainide and metoprolol on the reduction of PVCs as measured on Holter registration. SECONDARY OUTCOME: The function of the left and right ventricle as measured by echocardiography and cardiac magneticresonance imaging, and NT‐pro‐BNP levels in the blood. INCLUSION CRITERIA: ‐ Age ¡Ý 1 year and < 18 years ‐ Structurally normal heart confirmed by echocardiography ‐ PVCs > 15% on two different 24‐hour Holter recording ‐ With or without asymptomatic VT