Management of Cardiac Arrhythmias During Pregnancy

Background

Physiological adaptive changes in the cardiovascular system may make pregnant women prone to arrhythmia.¹ The most well-known adaptive changes during pregnancy include direct cardiac electrophysiological effects of hormonal alterations, an increase of circulating blood volume and cardiac output, an increase of sympathetic tone, and hypokalemia.²

The frequency of premature (extra) beats and sustained tachyarrhythmias become higher in pregnant women or may happen for the first time during pregnancy. Although the majority of palpitations are benign, new-onset ventricular tachycardia (VT) should be examined carefully for possible underlying structural heart disease.³

For the benign arrhythmias that occur during pregnancy, treatment mainly takes the form of reassurance and recommendation about proper actions during symptomatic episodes.⁴ In the minority of cases that drug therapy or electrophysiology study and potential ablation are required, potential teratogenic effects of these treatments on the fetus should be considered. Heart palpitation is the most common cause for pregnant women to visit a cardiologist.⁵

The frequency of supraventricular or ventricular tachyarrhythmias may increase during pregnancy.⁶ However, in the absence of underlying heart disease, on rare occasions, atrial fibrillation (AF) and atrial flutter have been reported, and there is a low risk of new-onset paroxysmal supraventricular tachycardia (SVT) among pregnant women, with a 4% incidence.^7,8

Supraventricular and ventricular arrhythmias that require treatment occur in up to 15% (mean 5%) of patients with underlying congenital or structural heart disease during pregnancy, but are rare in healthy women.³

Management of SVT During Pregnancy

For the treatment of atrioventricular (AV) nodal reentry tachycardia and atrioventricular reentry tachycardia, follow the stepwise treatment³ below:

1) AV nodal reentry tachycardia or AV reentry tachycardia involving an accessory pathway could be terminated by vagal maneuvers.
2) If vagal maneuvers could not terminate the episode of SVT, the first line of drug treatment is i.v. adenosine.
3) If adenosine fails, the second line of drug treatment is i.v. metoprolol.
4) Prophylactic antiarrhythmic drug therapy is suggested for patients with intolerable symptoms or hemodynamic compromise due to the tachycardia.³

Management of Atrial Fibrillation and Atrial Flutter in Pregnant Women

AF and atrial flutter are rarely seen during pregnancy in patients without structural heart disease or hyperthyroidism; therefore, diagnosis and treatment of the underlying disease are the first steps in the management of these arrhythmias.⁹ In case of patients with hemodynamic instability, electrical cardioversion is the treatment of choice.³ For the pharmacological termination of atrial flutter and AF in hemodynamically stable patients without underlying heart disease, i.v. ibutilide or flecainide typically works, and may be used during pregnancy. However, very limited experience for i.v. ibutilide or flecainide use in pregnant women has been reported.³ Adenosine, digoxin, propranolol, procainamide, and flecainide are relatively safe to manage arrhythmias during pregnancy.⁹ For controlling heart rate, beta-blockers are the first choice and verapamil is the second alternative for treatment.³ In patients with severe symptoms while they are taking rate-controlling drugs, prophylactic antiarrhythmic drugs (e.g., sotalol, flecainide, or propafenone) may be helpful.³

Management of Ventricular Tachycardia in Pregnancy

Sustained VT is rare during pregnancy.⁹ Idiopathic right ventricular outflow tract tachycardia (RVOT) is the most frequent type of VT in patients with a normal heart, and should be treated with verapamil or a beta-blocker agent as prophylaxis in pregnant women with severe symptoms or hemodynamic compromise.³ Catheter ablation of idiopathic RVOT may be useful in drug-resistant cases. For acute treatment, pregnant women with hemodynamically unstable VT or ventricular fibrillation (VF) should be electrically cardioverted immediately.¹⁰ In women with sustained VT (not related to long QT) and a stable hemodynamic situation, acute therapy can be initiated with intravenous sotalol. In pregnant women with stable monomorphic VT, intravenous procainamide may help.¹¹ In treating therapy-resistant VT, amiodarone and/or implantable cardioverter-defibrillator (ICD) implantation should be considered to protect the mother’s life.³

Antiarrhythmic Medications in Pregnancy

The U.S. Food and Drug Administration (FDA) classified the majority of antiarrhythmic drugs as category C during the pregnancy, which means that potential benefits of the drug may justify the use of the drug in pregnant women, even with potential risks. Phenytoin, amiodarone, and atenolol — all classified as category D — should be avoided, and warfarin (category X) should not be used during pregnancy (except in pregnant women with a high risk of thromboembolism and the benefits of warfarin may outweigh the potential risks to fetus, such as patients with mechanical heart valves).¹²

Lidocaine, enoxaparin, sotalol, pindolol, and acebutolol are classified as category B drugs, which means that they are safer choices during pregnancy.^13-15 The characteristics, indications, and safety profile of antiarrhythmic drugs during pregnancy are listed in Table 1.¹⁶

Catheter Ablation During Pregnancy

If catheter ablation becomes necessary due to drug-refractory and intolerable tachyarrhythmia, it is better to postpone it to the second trimester (if possible) to be less harmful to the fetus.³

Conclusion

Benign arrhythmias should not be treated medically. Treatment should not be denied in malignant arrhythmias. Invasive procedures involving fluoroscopy should be avoided and reserved for drug-refractory and intolerable tachycardia.

Disclosure: The authors have no conflicts of interest to report regarding the content herein.   

References

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