Case of the Month: Management of Atrial Tachyarrhythmia in Pregnancy

26-year-old multiparous female approximately 25 weeks gravid presents to the Emergency Room with palpitations. Patient reports that this feels similar to an episode she had during her first pregnancy that resolved after 18 mg of Adenosine. Patient states she was watching television on the couch when symptoms began. Patient reports feeling some mild chest tightness, but denies severe, sharp, or pleuritic chest pain. She denies lightheadedness or shortness of breath.

On exam–

Vital signs: HR 210, BP 83/65, MAP 65, RR 18, O2 97%, afebrile. Patient is alert and oriented, with GCS 15, in no acute distress. Heart sounds tachycardia without obvious added sounds or murmurs. Breath sounds clear without wheezes, rales, or rhonchi. Abdomen mildly gravid but nontender. Intact distal pulses and cap refill.

In the setting of initial blood pressure defibrillator pads were placed and patient was given a 500 ml bolus of NS. Blood pressure improved to 110/65 and remained stable.

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What is the rhythm?

Treatment options for SVT in pregnancy:

Unstable:

Direct current (DC) cardioversion

Stable:

Vagal maneuvers such as valsalva.
Adenosine
1. Category C
2. Short half life
AV nodal blocking agents
1. Digoxin
  1. Category C
2. Calcium channel blockers
  1. diltiazem, verapamil
  2. Category C
3. Beta-1 selective blockers in the second or third trimester
  1. Minimal risk of intra-uterine growth restriction and premature delivery.
  2. Exception is atenolol which is category D.
4. Procainamide, flecainide, propafenone, sotalol, quinidine
  1. All category C, except Sotalol (category B).

Review of safety:

FDA Pregnancy Categories

Category A
- Adequate and well-controlled studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters).
Category B
- Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.
Category C
- Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Category D
- There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Category X
- Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits.

Safety of antiarrhythmic drugs during pregnancy are based on observational data.
Electrical cardioversion can be performed at all stages of pregnancy.
- Fetal rhythm monitoring is recommended.
Adenosine, digoxin, verapamil, diltiazem, and procainamide have no evidence of increased risk of teratogenesis or increased risk of adverse fetal/neonatal effects (Category C).
- These are also safe in breastfeeding.
Beta blockers:
- (Category C)
- Prolonged use has risk of fetal growth restriction.
- Newborns of women taking these drugs near delivery are at risk of bradycardia, hypoglycemia, and other symptoms of beta-blockade.
- Atenolol is considered the highest risk of both and should be avoided. (category D)
Procainamide and Flecainide has been noted in animals but generally considered safe in refractory arrhythmias. Safe in breastfeeding. (Category C)
Quinidine safe, can cause preterm labor at very high doses. Safe in breastfeeding. (Category C)
NO amiodarone. (Category D)

Labs CBC, CMP, TSH were all within normal limits for pregnancy.

Seems to be SVT and with history of similar which resolved after adenosine, it seemed reasonable to treat again. A few vagal maneuvers were attempted as adenosine was drawn up without resolution

Patient had mentioned how much she hated the feeling of adenosine, and prior to pushing she seemed to hold her breath in preparation then suddenly she converted to a heart rate of 70. It seemed to be a sinus rhythm but prior to EKG her heart rate swift increased to a rate of 130-150.

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Now patient seems to be in Atrial fibrillation with Rapid Ventricular Response.

Options for treatment of AFib in pregnancy:

Unstable:

Direct current cardioversion

Stable:

Rate control of AF with AV nodal blocking agents
- Digoxin, beta blocker, or verapamil
Rhythm control: class IA (eg, quinidine, procainamide) or class 1C (flecainide, sotalol)
Catheter ablation can be considered in advanced centers for patients with frequent and symptomatic recurrences.

Anticoagulation:

Standard management
- If >48 hours, or unknown duration, perform TEE or systemic anticoagulation for three weeks prior to any cardioversion.
High CHA₂DS₂-VASc scores start anticoagulation until delivery.
- Low-dose aspirin (ASA) and low molecular weight heparin (LMWH) can be used at all stages of pregnancy.
- Heparin needs to be discontinued prior to delivery.
- Warfarin is generally not used during pregnancy because of its potential teratogenicity.
- Direct oral anticoagulants are not recommended because of the potential for fetotoxicity and lack of safety data.

Given Metoprolol IV 5 mg x 2 doses and 2L of NS total which improved rate to 102-108. Patient was then admitted for telemetry monitoring.

Take home points:

ELECTRICAL CARDIOVERSION IS SAFE with fetal monitoring after.
Vagal maneuvers then Adenosine then CCB or BB.
Digoxin also safe.
Procainamide or Flecainide for WPW.
Rate or rhythm control for afib. Pretty standard management.
NO amiodarone or atenolol.
Anticoagulation per CHA₂DS₂-VASc with LMWH.

Written by: Taylor Brittan, MD

Peer reviewed and edited by: Dylan Kellogg, MD

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