European Study on Maternal and Fetal Management of Fetal Supraventricular Tachyarrhythmia:Proposed Protocol for an International Project

Abstract

> Objectives: This European protocol is designed to estimate the efficacy of transplacental digoxin administered intravenously to the mother in sustained fetal supraventricular tachyarrhythmias (FSVT) with or without cardiac failure and in intermittent runs of FSVT with cardiac failure. The natural history of FSVT is evaluated in self-limited runs of FSVT without cardiac failure. Study structure: The fetal criteria for inclusion in the study are: gestational age <35 weeks, a normal cardiac anatomy, no severe extracardiac anomalies and a heart rate of the FSVT >200 beats/min. The maternal criteria include no prior treatment with digoxin or drugs effecting fetal heart rate and hemodynamics, and no contraindication to digoxin. Doppler fetal echocardiography is utilized for the diagnosis of the type of FSVT, sequential evaluation, and assessment of fetal hemodynamics. Fetuses are assigned two groups: Group I includes all fetuses with sustained FSVT and those with intermittent runs and cardiac failure; Group II comprises fetuses with intermittent runs and no cardiac failure. Fetuses in Group I will be treated. Group II will receive no treatment initially and will be observed. Treatment is based on a acute loading phase with digoxin administered intravenously to the mother for a period of 7 days. Doses are adjusted to through levels of maternal digoxin, maternal clinical condition, and electrocardiogram. If sinus rhythm is obtained, a maintenance phase follows with oral digoxin. Another drug, according to local experience and preference, is added to oral digoxin if digoxin intravenously fails to restore sinus rhythm and gestational age is <36 weeks. Post natal outcome will be followed by sequential clinical and Holter examinations. The data collected will be reviewed in a blinded fashion. The collection of the data for the protocol requires extensive information on the maternal, fetal, and long-term follow-up studies. They are detailed in the Appendix section. Expected results: We propose to obstetricians and pediatric cardiologists involved in fetal cardiology a rationale for the management and treatment of FSVT. Our expectation is to obtain a controlled study on a large number of cases at an international scale and thus provide a homogeneous maternal and fetal therapeutic strategy for FSVT.