Fetal supraventricular tachycardia: two cases of this fetal tachycardia following the administration of the Pfizer-BioNTech COVID-19 vaccine during pregnancy; is there a relationship?

by Paul Alexander

is there a direct connection to the COVID gene injection (vaccine)? The problem is Pfizer & Moderna did not study these outcomes nor for the duration for proper safety testing; safety is UNKNOWN


‘Fetal supraventricular tachycardia accounts for 60-80% of the fetal tachyarrhythmias with prevalence ranging from 1/1000 to 1/25 000 pregnancies. It may be secondary to fetal anomalies or maternal factors. By reviewing the literature, there is no previous article that reports fetal arrhythmia after maternal vaccination. We present herein two cases of fetal supraventricular tachycardia following the administration of the Pfizer-BioNTech COVID-19 vaccine during pregnancy. Continued safety monitoring and more longitudinal follow-up are needed to evaluate the fetal impact after maternal COVID-19 vaccination.’




Case presentation 1

A 27-year-old woman, gravida 2 para 0 aborta 1 presented at 31+1 weeks for a routine antenatal visit. Her medical and obstetric history was unremarkable. Her pregnancy course was uneventful apart Pfizer-BioNTech COVID-19 vaccination at 14+4 weeks and 17+4 weeks first and second dose respectively. During her routine ultrasound, a fetal supraventricular tachycardia was incidentally identified with 220 bpm. There was no history of fever, thyrotoxicosis or excessive consumption of caffeine. Further investigations were done and showed normal maternal electrocardiogram (EKG), metabolic panel, blood count and thyroid function. The fetal sonographic scanning was normal except for a minimal pericardial effusion with no evidence of hydrops fetalis. A fetal echocardiogram was performed and revealed a structurally normal heart. The patient was admitted and digoxin 0.5 mg per os was started every 12 h. During the whole course of treatment, maternal serum digoxin, electrolytes and EKG were monitored. Fetal cardiac rate became normal after 4 days. The patient was discharged with digoxin 0.25 mg every 12 h until delivery with a plan for nonstress test weekly and continued follow-up with her obstetrician and cardiac pediatrician.

She presented at the labor and delivery room at 38+5 weeks with spontaneous labor. She delivered vaginally a healthy male baby with a normal heart rate. Fetal echocardiogram was normal. He started amiodarone 500 mg/m2/j for 8 days and then 250 mg/m2/j for 6 months with monitoring TSH on days 3, 10, 40 and after 6 months. He stayed in the neonatal intensive care unit for heart rate monitoring, and he was discharged after 5 days with follow-up with the cardiac pediatrician.

Case presentation 2

A 34-year-old female, gravida 3, para 1, aborta 1 presented to the antenatal clinic for a routine visit at 29+2 weeks of gestation. The patient is known to have primary hypertension treated during pregnancy with methyldopa 250 mg every 12 h and nifedipine 30 mg per day. She also developed gestational diabetes, treated with insulin injections. The patient has received her first Pfizer-BioNTech COVID-19 vaccine at 27+4 weeks. Her obstetric history was unremarkable until this day. A fetal supraventricular tachycardia with a rate of 230 bpm was identified incidentally by routine ultrasound. No signs of hydrops fetalis, pericardial effusion or abnormal amniotic fluid index were identified. Full investigations revealed no maternal cause for the fetal arrhythmia. A fetal echocardiogram revealed a structurally normal heart.

Transplacental antiarrhythmic treatment was immediately initiated with digoxin 0.5 mg orally twice daily as a loading dose followed by a maintenance dose of 0.25 mg once daily until delivery. Bisoprolol 5 mg once daily was started instead of antihypertensive drugs. A fetal sinus rhythm was detected after 12 h of the start of the treatment with a rate of 143 bpm. Maternal serum digoxin levels, as well as electrolytes, were monitored and EKGs were done routinely. Nonstress tests were conducted on a weekly basis and close follow-ups with both her obstetrician and cardiac pediatrician were maintained.

The patient then received her second dose of the Pfizer-BioNTech COVID-19 vaccine at 31+3 weeks.

Preterm labor occurred at 33+3 weeks, 2 weeks after the administration of the second dose of the vaccine. There was no sign of maternal infection. An elective cesarean section took place under, uneventfully delivering a healthy male infant with a normal heart rate. The baby was kept under observation and arrhythmia recurred eventually at day 4 postnatally. Treatment was then launched, and the baby received amiodarone with a loading dose of 500 mg/m2/j per day for a total period of 8 days followed by a maintenance dose of 250 mg/m2/j once daily for a period of 6 months, associated with digoxin 25 mg twice daily. A fetal echocardiogram performed showed no anomalies. Rhythmic Holter is to be performed at 3 months old, and a follow-up with the pediatrician shall be kept for further evaluation.