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9.3.2 Ongoing Management: Recommendations IIa C-LD 1. Intravenous metoprolol or propranolol is reasonable for acute treatment in pregnant patients with SVT when adenosine is ineffective or contraindicated.516 See Online Data Supplement 20. Beta-adrenergic–blocking drugs are considered the first-line option for a variety of arrhythmias in pregnancy because there are extensive reports on their safe use from treating a variety of maternal conditions over many decades. A slow infusion would be less likely to cause hypotension.516,517,521 IIb C-LD 1. Intravenous verapamil may be reasonable for acute treatment in pregnant patients with SVT when adenosine and beta blockers are ineffective or contraindicated.516 See Online Data Supplement 20. Intravenous verapamil has been used effectively for the acute treatment of SVT in pregnant women; however, there is a higher risk of maternal hypotension with intravenous verapamil than with adenosine.516 Reports on diltiazem use for acute SVT termination in pregnancy are more limited than for verapamil, yet similar effects are expected.517 IIb C-LD 2. Intravenous procainamide may be reasonable for acute treatment in pregnant patients with SVT.522 See Online Data Supplement 20. Intravenous procainamide has been used safely to treat a variety of maternal and fetal supraventricular and ventricular arrhythmias and can be effective when used for acute conversion.517,522 Procainamide is generally best avoided as long-term therapy because it can cause a lupuslike syndrome, unless other options are contraindicated or ineffective. IIb C-LD 3. Intravenous amiodarone may be considered for acute treatment in pregnant patients with potentially life-threatening SVT when other therapies are ineffective or contraindicated.517,523 See Online Data Supplement 20. Although intravenous amiodarone has been administered safely during pregnancy, multiple adverse effects to the fetus have also been reported.523 An important concern is the possibility of fetal hypothyroidism, reported in approximately 17% of cases.517,523 With an intravenous infusion for short-term use, side effects would be less of a concern, given that most toxicities are related to cumulative drug dose. Recommendations for Acute Treatment of SVT in Pregnant Patients (Continued) COR LOE Recommendations Recommendations for Ongoing Management of SVT in Pregnant Patients COR LOE Recommendations IIa C-LD 1. The following drugs, alone or in combination, can be effective for ongoing management in pregnant patients with highly symptomatic SVT: a. Digoxin437,517 b. Flecainide437,517 c. Metoprolol517,521 d. Propafenone517 e. Propranolol517,521 f. Sotalol437,517 g. Verapamil517 See Online Data Supplement 20. If possible, antiarrhythmic drugs should be avoided in the first trimester, when risk of congenital malformations is greatest. Almost no reports exist on the use of newer antiarrhythmic drugs (such as dofetilide) during pregnancy, yet their use may be justified if the benefits outweigh the risk. The lowest recommended dose should be used initially, with dose adjustments made according to clinical response. For oral chronic prophylaxis, drugs such as metoprolol, propranolol, and digoxin are considered safe first-line agents because of their longer record of safety, yet caution is advised, given that therapy with beta blockers has been associated with intrauterine growth retardation.517,524 This effect appears to be especially pronounced with atenolol, especially in mothers who received atenolol earlier in gestational age and who were treated for longer duration.525 Flecainide and propafenone have been used effectively to treat a variety of maternal and fetal tachycardias, yet they are reserved for patients who have no underlying structural heart disease or ischemic heart disease.113 IIb C-LD 1. Catheter ablation may be reasonable in pregnant patients with highly symptomatic, recurrent, drug-refractory SVT with efforts toward minimizing radiation exposure.526,527 See Online Data Supplement 20. The risk of radiation exposure to the fetus is a concern with catheter ablation in pregnant patients, because high-dose ionizing radiation has been linked to excess malignancy and congenital malformations.528 However, the fetal radiation dose for most common cardiovascular interventions is not likely to exceed the 50-mGy negligible-risk threshold dose for excess malignancy.529 One study that used phantoms to simulate pregnancy estimated a low lifetime risk of malignancies from radiation exposure to the conceptus during a typical ablation procedure.527 Furthermore, with current technologies such as electroanatomic mapping systems, catheter ablation procedures using minimal or even zero fluoroscopy have been described in pregnant women.526 Thus, if a catheter ablation procedure is required in a pregnant woman, radiation-reduction technologies should be used, and the procedure should be avoided in the first trimester when the teratogenic risk is greatest.528 Of note, shielding the fetus by covering the mother with a lead apron does not eliminate radiation to the fetus because most of the radiation to the fetus comes from scatter. IIb C-LD 2. Oral amiodarone may be considered for ongoing management in pregnant patients when treatment of highly symptomatic, recurrent SVT is required and other therapies are ineffective or contraindicated.517,523 See Online Data Supplement 20. Although oral amiodarone has been administered safely during pregnancy, multiple adverse effects to the fetus have also been reported.523 An important concern is the possibility of fetal hypothyroidism, reported in approximately 17% of cases.517,523 Therefore, fetal monitoring for development of goiter with ultrasound and for signs of clinical hypothyroidism is advised. In addition, amiodarone has the potential for direct neurotoxicity, which may lead to neurodevelopmental abnormalities.523 Downloaded from http://ahajournals.org by on October 7, 2026