Prospective Observational Cohort Study of Fetal Atrial Flutter & Supraventricular Tachycardia (FAST Registry)
![]() |
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. |
ClinicalTrials.gov Identifier: NCT03376438 |
Recruitment Status :
Recruiting
First Posted : December 18, 2017
Last Update Posted : August 16, 2021
|
- Study Details
- Tabular View
- No Results Posted
- Disclaimer
- How to Read a Study Record
Condition or disease | Intervention/treatment |
---|---|
Atrial Flutter Tachycardia, Supraventricular Tachycardia, Atrial Ectopic Tachycardia, Reciprocating Tachycardia Atrial Tachycardia, Atrioventricular Nodal Reentry Tachycardia, Paroxysmal Fetal Hydrops | Other: Prospective observational cohorts |
Few studies are specifically designed to address health concerns relevant during pregnancy. The consequence is a lack of evidence on best clinical practice. This includes mothers and their babies when pregnancy is complicated by an abnormally fast heart rate up to 300 beats per minute due to supraventricular tachyarrhythmia (SVA) in the unborn baby (fetus). Although fetal SVA, including AF and other forms of SVT, is the most common cause of intended in-utero fetal therapy, our knowledge of drug effects on the baby and the co-treated mother is still limited. The Fetal Atrial Flutter and Supraventricular Tachycardia (FAST) Therapy Trial is a prospective multi-center trial to address this knowledge gap in order to guide future patient management to the best of care.
FAST Trial components include:
- A prospective Registry (FAST Registry; see this document) as well as
- Three prospective Randomized Clinical Trials (FAST RCTs; see ClinicalTrials.gov #NCT02624765).
The FAST Registry is a prospective observational cohort study to determine the impact of different prenatal treatment strategies on patients diagnosed with fetal AF without hydrops, AF with hydrops, SVT without hydrops, and SVT with hydrops. All management decisions including the choice of antiarrhythmic medication or the decision to observe without treatment are at the discretion of the treating physician. The primary outcome measure will be the proportion of term deliveries of live-born children with a normal cardiac rhythm. Secondary outcome measures include the efficacy of 1st line, 2nd line, 3rd line, and maintenance drug therapy in controlling the different arrhythmias prior to birth and patient safety.
Participation of a site in the FAST Registry requires experience with the perinatal management of fetal AF and SVT, local REB/IRB approval and an executed legal contract with the Hospital for Sick Children, Toronto.
Participation of a patient in the FAST Registry requires that all inclusion and none of the exclusion criteria are fulfilled (see below). Enrollment is possible within 2 days of the arrhythmia diagnosis and the initial management decision.
Study Type : | Observational |
Estimated Enrollment : | 1000 participants |
Observational Model: | Cohort |
Time Perspective: | Prospective |
Official Title: | FAST Trial Registry: Prospective Observational Cohort Study of Fetal Atrial Flutter & Supraventricular Tachycardia |
Actual Study Start Date : | June 8, 2017 |
Estimated Primary Completion Date : | May 31, 2027 |
Estimated Study Completion Date : | May 31, 2027 |

Group/Cohort | Intervention/treatment |
---|---|
Prospective observational cohorts
1) Atrial flutter without fetal hydrops; 2) Atrial flutter with fetal hydrops; 3) Supraventricular tachycardia without fetal hydrops; and 4) Supraventricular tachycardia with fetal hydrops
|
Other: Prospective observational cohorts
Patients with AF or SVT that is significant enough to consider prenatal treatment are eligible for enrollment. Management decisions are made at each patient encounter by the primary physician based on clinical findings and may include: 1) no antiarrhythmic treatment; 2) transplacental antiarrhythmic treatment; 3) direct fetal antiarrhythmic treatment; 4) delivery. Patients enrolled in the FAST Registry will be followed from the time of enrollment until the baby is discharged after birth.
Other Name: Non-randomized antiarrhythmic fetal drug therapy |
- Proportion of live-born children with a delivery at term and a normal cardiac rhythm [ Time Frame: Term: 37 0/7 to 41 6/7 weeks ]
- Proportion of patients with cardioversion over time [ Time Frame: From date of SVA dignosis until the date of first documented cardioversion or until the date of delivery/fetal death without cardioversion, whichever comes first, assessed up to 30 gestational weeks ]Number of participants with persistent tachycardia compared to number of participants with cardioversion to a normal rhythm over time
- Proportion of participants with treatment failure [ Time Frame: From date of treatment start until the date of first documented fetal cardioversion or until the date of treatment failure, whichever comes first, assessed up to 30 gestational weeks ]Number of participants with treatment failure compared to number of participants with successful treatment. Treatment failure is defined as one of the following: 1) cross-over to another drug; 2) SVT/AF that persists to birth; 3) preterm birth; 4) death.
- Proportion of participants with arrhythmia-related death [ Time Frame: From date of arrhythmia diagnosis or date of treatment start to 30 days of life ]Number of participants with arrhythmia-related death compared to other outcomes
- Average gestational age at birth [ Time Frame: At birth ]
- Birth weight (z-scores; centiles) [ Time Frame: At birth ]
- Total days of treatment related maternal and neonatal hospitalizations [ Time Frame: From date of diagnosis or treatment begin to 30 days of life ]
- Maternal prevalence of pregnancy/treatment-related AEs and outcomes [ Time Frame: Diagnosis to birth ]
- Maternal prevalence of adverse events and outcome [ Time Frame: From date of treatment begin to 30 days of life ]

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | 16 Years to 50 Years (Child, Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | No |
Sampling Method: | Probability Sample |
Inclusion Criteria:
- Mother has provided written informed consent to participate
- Fetal AF or SVT with or without hydrops
-
Tachyarrhythmia that is significant enough to justify immediate transplacental pharmacological treatment:
- Tachycardia ≥ 180 bpm during at least 10% of observation time of 30 minutes or longer
- Tachycardia ≥ 170 bpm during +100% of time (≤ 30 0/7 weeks of gestation)
- Tachycardia ≥ 280 bpm (irrespective of SVA duration)
- SVT with fetal hydrops (irrespective of duration)
- Gestational age <36 0/7 weeks at time of enrollment
- 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
- Maternal resting heart rate ≥ 50 bpm
- Maternal systolic BP ≥ 85 mmHg
Exclusion Criteria:
- Primary delivery for postnatal cardioversion
- Antiarrhythmic fetal treatment for more than 2 days at time of enrollment
- Any maternal-fetal conditions associated with high odds of premature delivery and/or death
- History of significant maternal heart condition (open heart surgery; sick sinus syndrome; long QT, Brugada syndrome; ventricular tachycardia; WPW syndrome; high-degree heart block; cardiomyopathy)

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03376438
Contact: Diana Balmer-Minnes, BSc, CCRP | 416-813-7654 ext 228624 | FAST.Trial@sickkids.ca | |
Contact: Prachi Sharma, MSc, CCRA | 416-813-7654 ext 309423 | FAST.Trial@sickkids.ca |

Principal Investigator: | Edgar Jaeggi, MD, FRCPC | The Hospital for Sick Children, Toronto, ON, Canada |
Responsible Party: | Edgar Jaeggi, Edgar Jaeggi, MD FRCP (C), Section Head, Fetal Cardiac Program, The Hospital for Sick Children |
ClinicalTrials.gov Identifier: | NCT03376438 |
Other Study ID Numbers: |
1000048953 |
First Posted: | December 18, 2017 Key Record Dates |
Last Update Posted: | August 16, 2021 |
Last Verified: | August 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
Hydrops Fetalis Tachycardia Atrial Flutter Tachycardia, Supraventricular Tachycardia, Atrioventricular Nodal Reentry Tachycardia, Paroxysmal Tachycardia, Ectopic Atrial Tachycardia, Reciprocating Arrhythmias, Cardiac Heart Diseases Cardiovascular Diseases Cardiac Conduction System Disease |
Pathologic Processes Edema Erythroblastosis, Fetal Fetal Diseases Pregnancy Complications Hematologic Diseases alpha-Thalassemia Thalassemia Hemoglobinopathies Genetic Diseases, Inborn Immune System Diseases Anti-Arrhythmia Agents |