The pacing rate is programmed to maintain atrial pacing for the majority of the time in patients with sinus node dysfunction, significantly reducing tachycardia recurrences to 11% in 1 study.509,510 In addition, the implanted pacemaker can be used for termination of recurrent episodes of AT or atrial flutter.472 Recommendations for Ongoing Management of SVT in ACHD Patients (Continued) COR LOE Recommendations Page et al 2015 ACC/AHA/HRS SVT Guideline e553 Pregnancy may confer an increased susceptibility to a variety of arrhythmias, even in the absence of underlying heart Pregnancy is also associated with an increased risk of arrhythmia exacerbation, such as more frequent and refractory tachycardia episodes, in patients with a pre-existing An important consideration is that adverse maternal and fetal outcomes have been reported as a result of SVT in pregnancy.515 Although there is potential tox- icity to the fetus with certain pharmacological and nonphar- macological therapies, safe options exist to allow for treating most cases of maternal SVT effectively. The literature on therapeutic options for the management of arrhythmias in pregnancy is generally limited to single case reports or small series and favors the use of older antiarrhyth- mic agents because of more abundant reports on the safe use of these drugs. Experience with use of drugs in pregnancy also comes from treating a variety of maternal and fetal condi- tions, not maternal SVT alone. Although all medications have potential side effects to both the mother and the fetus at any stage of pregnancy, if possible, drugs should be avoided in the first trimester, when risk of congenital malformations is great- est. The lowest recommended dose should be used initially, accompanied by regular monitoring of clinical response. 9.3.1. Acute Treatment: Recommendations IIb B-NR 2. 