Fetal Atrial Flutter & Supraventricular Tachycardia (FAST) Therapy Trial

Recruitment & Eligibility

Status: Complete

Sex: Female

Target Recruitment: 105

Inclusion Criteria

•Mother has provided written informed consent to participate in the RCT
•Mother aged =18 years at time of enrolment
•Fetal AF without hydrops (RCT A) or SVT without hydrops (RCT B) or SVT with hydrops (RCT C)
•Tachyarrhythmia that is significant enough to justify immediate transplacental pharmacological treatment:
- Tachycardia = 170 bpm during +100% of time (= 30 0/7 weeks of gestation)
- Tachycardia = 180 bpm during at least 10% of observation time
- Tachycardia = 280 bpm
- Tachycardia with fetal hydrops
•Gestational age = 12 0/7 weeks and <36 0/7 weeks at time of enrolment
•Untreated arrhythmia at time of enrolment
•Singleton Pregnancy
•Healthy mother with ± normal pre-treatment cardiovascular findings:
- ECG within normal range (sinus rhythm; QTc = 0.47; PR = 0.2 sec; QRS: = 0.12 sec; insignificant anomalies isolated premature beats; isolated complete right bundle branch block;non-specific ST-T segment changes allowed)
- Maternal resting heart rate = 50 bpm
- Maternal Systolic BP = 85 mm Hg

Exclusion Criteria

•Fetal AF with hydrops (condition is too infrequent to be studied in a separate RCT sub-study; eligible for Registry)
•Any maternal-fetal conditions associated with high odds of premature delivery and/or death other than tachycardia (e.g. severe IUGR; premature rupture of membrane; life-threatening maternal disease (incl. pre-eclampsia; HELLP syndrome); severe congenital fetal abnormalities (T 13 or 18; surgery or death expected < 1 month))
•History of significant maternal heart condition (open heart surgery; sick sinus syndrome; channelopathy (long QT, Brugada syndrome); ventricular tachycardia; WPW syndrome; high-degree heart block; cardiomyopathy)
•History of significant maternal obstructive airway disease including asthma
•Maternal serum potassium level < 3.3mmol/L / <3.3 mEq/L
•Maternal ionized serum calcium level of <1 mmol/L / <4mg/dL or total serum calcium level <2mmol/L / < 8mg/dL
•Maternal serum creatinine level > 97.2 µmol/L (>1.1 mg/dl)
•Maternal intake of QT-prolonging medication including but not limited to the following medications: http://www.crediblemeds.org/pdftemp/pdf/CompositeList.pdf

Study & Design

Study Type: interventional

Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
proportion of term deliveries of live-born children with a normal cardiac rhythm. Term delivery is defined as birth 37 0/7 weeks gestation or later

Secondary Outcome Measures

Name	Time	Method
•Proportion of participants with cardioversion over time.<br>•Proportion of participants with treatment failure: <br>oNumber of participants with treatment failure compared to number of participants with successful treatment. Treatment failure is defined as one of the following:<br>- cross-over to another drug<br>- SVT/AF that persists to birth<br>- preterm birth<br>- death <br>•Cause of death (prenatal, postnatal) Proportion of participants (infants) with arrhythmia related death<br>•Average gestational age at birth<br>•Birth weight (z-scores)<br>•Average days of maternal and neonatal hospitalization related to SVA therapy<br>•Maternal prevalence of pregnancy/treatment-related AEs and outcomes Proportion of AEs / adverse outcomes (prenatal, postnatal)<br>

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