Flecainide in Pregnancy and Breastfeeding

Risk Factor: CM
Class: Cardiovascular drugs / Cardiac drugs

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary
Questions and Answers

Fetal Risk Summary

Flecainide is an antiarrhythmic agent that is structurally related to encainide and procainamide. In one breed of rabbits, flecainide produced dose-related teratogenicity and embryotoxicity at approximately 4 times the usual human dose (1). Structural defects observed were club paws, sternebrae and vertebrae abnormalities, and pale hearts with contracted ventricular septum. Similar toxic effects and malformations were not observed in a second breed of rabbits, or in mice and rats, but dose-related delayed sternebral and vertebral ossification was observed in rat fetuses (1).

Two 1988 reports of human use of flecainide during pregnancy may have described a single incidence of exposure to the drug (2,3). Intravenous flecainide was given to a pregnant woman at 30 weeks' gestation for persistent fetal supraventricular tachycardia resistant to digoxin (2,3). The fetal heart rate pattern quickly converted to a sinus rhythm and the mother was maintained on oral flecainide, 100 mg 3 times daily, until delivery was induced at 38 weeks' gestation. The 3450g female infant had no cardiac problems during the 10 days of observation. Flecainide concentrations in the cord blood and maternal serum at delivery 5 hours after the last dose were 533 and 833 ng/mL, respectively, a ratio of 0.63 (2).

Flecainide 100 mg twice daily, combined with the b-blocker sotalol, was used throughout gestation in one woman for the treatment of ventricular tachycardia and polymorphous ventricular premature complexes associated with an aneurysm of the left ventricle (4). A cesarean section was performed at approximately 37 weeks' gestation. Flecainide concentrations in umbilical cord and plasma samples at delivery, 11 hours after the last dose, were 0.394 and 0.455 g/mL, respectively, a ratio of 0.86. No adverse effects, including bradycardia, were observed in the fetus or newborn, who was growing normally at 1 year of age.

A 22-year-old woman at approximately 31 weeks' gestation was treated with flecainide, 100 mg every 8 hours, for fetal arrhythmia associated with fetal hydrops unresponsive to therapeutic levels of digoxin (5). Therapeutic levels of flecainide were measured in the mother over the next 4 days, during which time the fetal heart rate (FHR) converted to a normal sinus rhythm of 120 beats/minute. Approximately 2 days later, a nonreactive nonstress test was documented and flecainide and digoxin were discontinued, but the FHR returned to pretreatment levels within 36 hours. Flecainide was restarted at 150 mg every 12 hours, and within 30 minutes of the first dose, the FHR converted to normal. This dose was continued for 4 days, during which time the FHR remained normal at 120 beats/minute, but with a nonreactive nonstress test. Gradual reduction of the dose to 50 mg every 12 hours maintained a normal FHR with return of a reactive nonstress test and normal beat-to-beat variability. Fetal ascites was completely resolved after 10 days of therapy. A normal 3480-g infant, Apgar scores of 9 and 10 at 1 and 5 minutes, respectively, was delivered vaginally at 41 weeks' gestation. Maternal and fetal serum trough levels at delivery were 0.2 and 0.1 g/mL, respectively (5). A postnatal echocardiogram performed on the newborn was normal.

A 1991 report described the experimental use of flecainide, 300400 mg/day orally, in 14 women at a mean gestational age of 31 weeks (range 2336 weeks) to treat fetal hydrops and ascites secondary to supraventricular tachycardias or atrial flutter (6). The duration of treatment ranged from 2 days to 5 weeks. Although specific data were not given, the cord:maternal plasma ratio at birth was approximately 0.80, and all fetuses had flecainide concentrations within the usual therapeutic range (400800 g/L). Twelve of the 14 newborns were alive and well at the time of the report, and one infant, not under treatment at the time, died of sudden infant death syndrome at 4.5 months of age. One intrauterine death occurred after 3 days of therapy and may have been caused by either a flecainide-induced arrhythmia or fetal blood sampling (6).

A woman in the 3rd trimester was initially treated with flecainide 100 mg orally twice daily, then decreased to 50 mg twice daily, for fetal tachycardia that resolved within 4 days (7). The fetal ascites and polyhydramnios also resolved around this time. Approximately 6 weeks after treatment was begun, she gave birth to a 3320-g, male infant. The cord blood:maternal serum ratio of the drug was 0.97 (235.4/241.2 ng/mL), but the flecainide concentration in the amniotic fluid was 6426.5 ng/mL, about 27 times the level in the fetus.

Other publications have described the successful use of flecainide for the treatment of fetal tachycardia (8,9,10,11,12,13 and 14), and in one of these, flecainide and digoxin were considered the drugs of choice for this condition (8). However, flecainide is superior to digoxin for the treatment of tachycardia in hydropic fetuses (9,10).

The loss of fetal heart rate variability and accelerations was described in a case of supraventricular tachycardia treated with 300 mg/day of flecainide during the 3rd trimester (11). The heart rate of the 3690-g male infant returned to a reactive pattern 5 days after delivery. One day later, the infant's serum concentration of flecainide was below the detection level. A general review of drug therapy used for the treatment of fetal arrhythmias was published in 1994 (12). Flecainide has also been used to treat new onset maternal ventricular tachycardia presenting during the 3rd trimester (15).

Conjugated hyperbilirubinemia thought to be caused by flecainide was described in a 1995 Reference (16). Flecainide, 150 mg twice daily, was started at about 28 weeks' gestation for the treatment of fetal supraventricular tachycardia after a trial of digoxin and adenosine had failed to halt the arrhythmia. Other fetal complications, in addition to the arrhythmia, were polyhydramnios, ascites, pericardial effusion, cardiomegaly, and tricuspid and mitral valve regurgitation. Successful conversion to a sinus rhythm occurred within 24 hours. The mother discontinued the therapy 1 week later, and a second course of flecainide was started when the fetal tachycardia and ascites reoccurred. The 2843-g, male infant, delivered vaginally at 36 weeks, developed transient conjugated hyperbilirubinemia within a few days of birth. The authors attributed the hyperbilirubinemia to flecainide because no other cause of the toxicity could be found and the drug is known to produce a similar condition in adults. Follow-up of the infant at 2 months of age revealed that the liver toxicity had resolved and at 28 months of age, the child was continuing to do well (16).

Breast Feeding Summary

Flecainide is concentrated in human breast milk (4,17), but no reports of infant exposure to the drug from nursing have been located. A woman was treated throughout gestation and in the postpartum period with flecainide, 100 mg twice daily, and sotalol (see Sotalol) (4). Simultaneous samples of milk and plasma were drawn 3 hours after the second daily dose on the 5th and 7th days postpartum. Flecainide concentrations on day 5 were 0.891 and 0.567 g/mL, respectively, and 1.093 and 0.500 g/mL, respectively, on day 7. Milk:plasma ratios were 1.57 and 2.18, respectively. The infant was not breast-fed (4).

Eleven healthy women volunteers who intended not to breast feed were given flecainide 100 mg orally every 12 hours for 5.5 days starting on postpartum day 1 (17). The breasts were emptied by a mechanical breast suction pump every 34 hours during the study. Peak milk levels of the drug occurred at 36 hours after a dose with a mean half-life of elimination of 14.7 hours. The highest daily average concentration of the drug ranged from 270 to 1529 ng/mL, with milk:plasma ratios on days 2, 3, 4, and 5 of 3.7, 3.2, 3.5, and 2.6, respectively. An estimated maximum steady state concentration of flecainide in an infant consuming approximately 700 mL of milk per day (assumed to be the total milk production) was 62 ng/mL, an apparently nontoxic level. Based on this, the investigators concluded that the risk of adverse effects in a nursing infant whose mother was consuming flecainide was minimal (17). The American Academy of Pediatrics considers flecainide to be compatible with breast feeding (18).


  1. Product information, Tambocor. 3M Pharmaceuticals, 1993.
  2. Wren C, Hunter S. Maternal administration of flecainide to terminate and suppress fetal tachycardia. Br Med J 1988;296:249.
  3. Macphail S, Walkinshaw SA. Fetal supraventricular tachycardia: detection by routine auscultation and successful inutero management: case report. Br J Obstet Gynaecol 1988;95:10736.
  4. Wagner X, Jouglard J, Moulin M, Miller AM, Petitjean J, Pisapia A. Coadministration of flecainide acetate and sotalol during pregnancy: lack of teratogenic effects, passage across the placenta, and excretion in human breast milk. Am Heart J 1990;119:7002.
  5. Kofinas AD, Simon NV, Sagel H, Lyttle E, Smith N, King K. Treatment of fetal supraventricular tachycardia with flecainide acetate after digoxin failure. Am J Obstet Gynecol 1991;165:6301.
  6. Allan LD, Chita SK, Sharland GK, Maxwell D, Priestley K. Flecainide in the treatment of fetal tachycardias. Br Heart J 1991;65:468.
  7. Bourget P, Pons J-C, Delouis C, Fermont L, Frydman R. Flecainide distribution, transplacental passage, and accumulation in the amniotic fluid during the third trimester of pregnancy. Ann Pharmacother 1994;28:10314.
  8. van Engelen AD, Weijtens O, Brenner JI, Kleinman CS, Copel JA, Stoutenbeek P, Meijboom EJ. Management outcome and follow-up of fetal tachycardia. J Am Coll Cardiol 1994;24:13715.
  9. Simpson JM, Sharland GK. Fetal tachycardias: management and outcome of 127 consecutive cases. Heart 1998;79:57681.
  10. Wren C. Mechanisms of fetal tachycardia. Heart 1998;79:5367.
  11. van Gelder-Hasker MR, de Jong CLD, de Vries JIP, van Geijn HP. The effect of flecainide acetate on fetal heart rate variability: a case report. Obstet Gynecol 1995;86:6679.
  12. Ito S, Magee L, Smallhorn J. Drug therapy for fetal arrhythmias. Clin Perinatol 1994;21:54372.
  13. Amano K, Harada Y, Shoda T, Nishijima M, Hiraishi S. Successful treatment of supraventricular tachycardia with flecainide acetate: a case report. Fetal Diagn Ther 1997;12:32831.
  14. Jaeggi E, Fouron JC, Drblik SP. Fetal atrial flutter: diagnosis, clinical features, treatment, and outcome. J Pediatr 1998;132:3359.
  15. Connaughton M, Jenkins BS. Successful use of flecainide to treat new onset maternal ventricular tachycardia in pregnancy. Br Heart J 1994;72:297.
  16. Vanderhal AL, Cocjin J, Santulli TV, Carlson DE, Rosenthal P. Conjugated hyperbilirubinemia in a newborn infant after maternal (transplacental) treatment with flecainide acetate for fetal tachycardia and fetal hydrops. J Pediatr 1995;126:98890.
  17. McQuinn RL, Pisani A, Wafa S, Chang SF, Miller AM, Frappell JM, Chamberlain GVP, Camm AJ. Flecainide excretion in human breast milk. Clin Pharmacol Ther 1990;48:2627.
  18. Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 1994;93:13750.

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Questions and Answers

Is anyone else taking flecainide and have you drank with it?, I have been taking flecainide for a while now and was wondering if anyone else that is taking it has drank and if you have had any negative side effects to this. I have drank once but didnt take it that night because i didnt know what would happen.. please let me know!! thanks

Flecainide is indicated to reduce the conduction and contractility of the heart to stabilize the heart membrane. It's given to patients with an abnormally fast heart rhythm. If you take alcohol with it, it may cause your heart to slow down even more. You may risk hypotension which may also lead to death, depending on the severity of the reaction to alcohol that you drank. Be careful!

The only medicine that works for my persistent atrial fibrillation is Flecainide but I do not have health?, Insurance and it cost to much. Should I just see if I could have an ablation so I wouldn't have to take meds for it

Ablation for atrial fibrillation is also a costly procedure and the success rate is not 100% for persistent atrial fibrillation. If your symptoms are not well controlled, then there is a definite role for ablation. Please check up with your doctor regarding ablation in your case, as he is the best person to tell you the prospects in your case.

Flecainide and photosensitivity?, I take Flecainide twice a day for atrial fibrillation (100 g night and morning). My specialist told me that I can only spend 10 minutes in the sun before I have to cover up, long sleeves, hat and sunglasses. I find this a real bind as I feel very hot with long sleeves etc.
I am going on holiday to Italy this year in August so we will spend a lot of time in the swimming pool. Can I still get burnt if I keep most of my body under water? I hope that the water will act as a cooling agent but I have no idea really.
Also has anyone on Flecainide managed to use a sun screen succesfully instead of long sleeves?

yes, you will get burned if you are under water... in fact, you will burn quicker since the water reflects the rays... why don't you try a rash guard shirt that surfers wear? They are really thin, usually made out of the same material like swim suits and dry quickly. My kids wear them all the time so they don't burn but they never complain that they are hot in them. We live in the desert in California... with temperatures around 100+ degree F or around 40+ degree C

i have just been diagnosed with SVT. Is there anyone else outthere who is taking flecainide medication 4 it?, I was just diagnosed last nite after having a svt attack. My heart beat went to 240bpm and after an hour of the heart rate not going down i was given adenosine which was very scarey. I am now on a waiting list to see a cardiologist. When i told them i was going on holiday next week they decided to put me on medication just in case. They put me on flecainide 50mg two times a day. Is anyone else on this medication for svt. I read the side effects and they appear to be endless? also cos im going on holiday i wanted to know if i can drink a resonable amount of alchol with this medication? If anyone has any information it would really help!

Flecainide in an anti-arrhythmic drug which works by correcting irregular heartbeats and slowing down the speed at which your heart beats.
It is usually taken twice a day (every 12 hours). You need to know how your body reacts to flecainide before you attempt to drive, use machinery etc. You are obviously aware of the (potential) side effects, so I won't go into that!
I'm assuming that you were hospitalised for your SVT and that you were in the A&E/ER dept when you were given adenosine. I'm a little suprised at your quick discharge, as usually flecainide is started in hospital, where you would be kept under close constant observation, so that they can assess how your heart reacts to the drug.
As it's only a week until your holiday, is there any chance that you could delay going away until both you and your doctor are sure that flecainide suits you? If you can't, then just to be on the safe side, I'd advise that you make a note of the address and telephone number of the hospital closest to where you will be staying. You could program this into your mobile phone. It may also be useful to carry some information in your wallet/purse to say that you are on flecainide for SVT.
Flecainide can make your skin more sensetive to sunlight, so you need to avoid exposure to strong sunlight and use a high factor (above factor 15) sunscreen until you know how your skin reacts.
It is recommended that alcohol should be avoided when you are taking flecainide (sorry!) as it may further depress normal heart function. It's also worth bearing in mind that alcohol can make you careless, and it's important to take your flecainide at the right time! Smoking can also reduce the absorption of flecainide.
Hope this is of some help to you. Good luck, have a great holiday!

what time of day should I take warfarin?, I have atrial fibrillation and take Warfarin. I used to take it every morning at the same time as my beta blocker and flecainide and never forgot. When I was in hospital the nurse said Warfarin should be taken at 6pm. This is not convenient as we eat mainly at midday and are out in the evening and twice I have forgotten to take the Warfarin. What difference would it make if I took it in the morning with my other tablets?
Also the anticoagulation clinic told me not to make up the missed dose the next morning - surely it is better than missing a dose completely? I take 5mg weekdays and 6mg at the weekend so obviously the amount is minutely measured and it seems to me that it would be better to make up the missing dose and anyway the 2 doses would be 10 hours apart. I was also told to mark my yellow card with the date of the missing dose althoug my INR test is only monthly now so it seems pointless or perhaps I am not understanding the way warfarin works..

Since Warfarin is rat poison (used in humans as a blood thinner) you should ask your doc and if they are unavailable ask the chemist.
The nurse most likely gave you 6pm due either to some interaction with another med you take at a specific time, or to make it easier on the hospital staff.
No matter what the logic was, consult your physician BEFORE making a change to your current dosing.
Good luck, HTH

Does anybody have experiences with infant SVT that they can share?, My son had two incidences - one at birth and one at three weeks. First was converted with adenoside in NICU and he was prescribed Digoxyn. The next was converted with adenosine and he went home from a second visit to NICU five days later on Flecainide. Wondering if anyone has similar experiences and what long-term outcome was. Planning on stopping Flecainide by 1 year old and wondering if SVT will come back.

I do not have any personal experience as far as one of my children or family members with SVT, but I perform EKGs everyday on everyone at my hospital including babies. Typically rhythm problems are sporadic to say the least. The general belief is that when a child has a rhythm problem it will subside later in development and medication should cease the episodes at an early age. You should expect to see more episodes and lots of other medication. Typically when a patient has rhythm abnormalities, initial medication fixes the problem but for some reason you see a recurrence of the abnormal rhythm and is fixed again with another medication. Strangest thing...happens all the time. Don't know why, and quite honestly I don't think many doctors know why. Typically it's a problem you learn to monitor and deal with as an episode occurs. Just give it time though, he may grow out of it when everything begins to develop along further. Sorry I couldn't be more help

medication for atrial fibrillation making me tired?, The medication for AF is making me very tired. After my latest episode this week when I needed oxygen and digoxin it was suggested by the hospital doctor that I increase my medication. I am very reluctant as I already take Bisoprolol (7.5 mg daily) and Flecainide (200 mg daily) plus warfarin. I thought that only bisoprolol made you tired but have just read that flecainide does the same. Are other people with AF taking this much and are they tired all the time and does anyone like me have a muzzy head and slow thinking and short term memory loss? Is it all in my imagination?
I did go 5 months without a fibrillation but have had 2 lasting 15 hours in the past 3 weeks, possibly due to a virus I picked up.

It is hard to tell if your exhaustion is due to the medications you are on, your atrial fibrillation, or the virus you picked up. Any of these could cause you to be more tired. Talk to your doctor. You might at least try the increased dosage for a week to see if symptoms improve or get worse.

Can AMY P the cardiologist please answer a few more of my questions please.?, Hi Amy this is what was in my cardiologists letter could you help me out by explaining what each bit means and how it will affect my future ( I am only 28 and have been diagnosed with PAF for the last 2 years , I am taking Flecainide (tambacor in USA) should I be taking this if I have decreased function in my left ventricle ? I have to waitt until october to see my cardiologist to explian these things to me!!!

Left ventricular dimensions were at the upper limit of normal with mild overall systolic impairment and some minor regional wall abnormality at the apex with a hyperkinetic mid anterior septum. There was a minor intra-ventricular conduction delay

Thanks AMY

If anyone else could help me as well I would be grateful


PAF=paroxsymal atrial fibrillation (this is a coming and going rhythm-hence paroxsymal). Other "foci" besides your SA node are firing spontaneously sending out multiple electrical impulses to your conduction system. The AV node can only respond to one at a time. But the top part of your heart(atria) are being stimulated to contract constantly, and therefore the bottom part of your heart (ventricles) are not recieving adequate volumes of blood. Over time the ventricles enlarge(to try and compensate and get more blood), then the muscle quality diminishes and hence overall decreased function. Why are you waiting until October? There are millions of qualified cardiologists around the world who could treat you. You most likely at this point need EP studies and possible ablation of those "extra foci", if not a pacemaker to "override" this rhythm and restore normal conduction. Hopefully at 28 your heart muscle will repair itself, but it's not 100% guaranteed. The other option is a possible cardioversion to "reboot" your electrical conduction system, and then a med less toxic to your systolic function to maintain your normal rhythm and promote healing of your heart muscle. Don't wait!!!!!!!!!!!!!!

I have SVT ( supraventricular tachycardia) my heart starts to go about 190 suddenly?, My heart starts beating about 190 when it starts, and it's suddenly.
My doctor gave me flecainide as medicine for it, i have to be takin it for 5 months. My heart starts beating fast suddenly when i do a sudden movement. The last time it started when i took a really deep breath. It's weird it only happend about every month or so. I get dizzy if i keep running or doing something that makes my heart beat even faster. it starts and stops suddenly. any advise about it?

Having rhythms that are symptomatic can be dangerous. You could be driving or on a ladder or swimming when the rhythm occurs having potentially dire results.

If medications have failed you - and I presume they have if you are now on flecanide and it is not working - then there is an ablation treatment that can be employed to correct the issue.

Basically they map where the impulse that is causing this problem is coming from. They then use a laser catheter to ablate (destroy) either the (a very small) area or the pathway that is causing the trouble. They access the heart via your large blood vessel (femoral vein) between your hip and your crotch on the right side.

Regardless whether they have trialed all of the medications or not, the ablation therapy is becoming more of a front line, initial therapy. It is a one time procedure. Additional therapies are not required. You often do not require medications either. Ask you cardiologist about this matter. You are looking to speak with an electrophysiolgist (a sub-specialist within cardiology)

See the link to the Mayo Clinic as an example below.

Good luck.

A fib& shortness of breath & energy loss.?, Do any other A fibbers have shortness of breath and loss of energy even when they are not fibrillating? This has only started since the increase in my episodes which were 3 times a year. I have now had six since May 11th and each time have been admitted to hospital and given oxygen and digoxin. They last longer - about 12 hours . I think my tiredness is due to too much medication (betablockers, flecainide, statins & the necessary warfarin). I have now read about vagal A Fib and I can tick every box, i.e. coming at night, after a meal or a drink, bending down etc. My GP has never heard of it although I have a hiatus hernia. The hospital think it could be coronary artery disease but I don't think so. I have just had a MIBI scan but the results will take 4-5 weeks! In 12 days time we will be touring France & Italy. I would like to think the problems could be caused by vagal A fib itself and if I eat wisely I will be OK until I return. I don't want to go to French or Italian hospitals

YOu're tiredness can be due to the a fib episodes as well as SOB. Do you see a cardiologist. Why couldn't it be CAD, you sound like a candidate or is that your denial speaking. I wouldn't be going anywhere until I know I'd survive.
Man, don't mess with your heart. Its VITAL!