That’s been the experience of clinicians at the combined fetal cardiovascular program at the University of California, San Francisco and University of California, Davis, described in a paper online March 22 in the American Journal of Cardiology.
“Our (paper) documents a single center’s approach to the treatment of fetal SVT with the use of sotalol as first line therapy,” Dr. Lisa K. Hornberger told Reuters Health. “We found sotalol to be safe and effective with complete or partial response in the majority (of cases) irrespective of arrhythmia mechanism, including some fetuses with hydrops,” added Dr. Hornberger, who is now director of the Fetal & Neonatal Cardiology Program and pediatric cardiologist, Stollery Children’s Hospital, University of Alberta.
She said most pregnancies that respond to this therapy “do so quite rapidly, within a couple of days.”
Digoxin is often used as first-line therapy for fetal SVT and atrial flutter, but it’s not always effective and is poorly transferred to the fetus in the presence of fetal hydrops, the researchers note in their report. For some time now, they’ve been using sotalol as an alternative to digoxin at presentation in fetuses with SVT or atrial flutter with or at risk of developing hydrops, with the aim of achieving more rapid control of the arrhythmia.
In their current paper, they report on 21 pregnancies with fetal tachycardia (16 with SVT and five with atrial flutter) managed at their center with sotalol at presentation, with or without concurrent administration of digoxin.
In 11 cases (6 SVT and five atrial flutter) tachyarrhythmia resolved within five days of treatment (median time to resolution, one day). Six others showed some response (but not complete resolution) in the form of less frequent tachyarrhythmia, rate slowing and resolution of hydrops.
In one fetus with a slow response, the mother chose to terminate her pregnancy. The five survivors with a slow response were all “difficult to treat postnatally,” the clinicians say. One required radiofrequency ablation as a neonate; one developed blocked atrial extrasystoles after one dose of sotalol and was prematurely delivered for fetal bradycardia; and three grossly hydropic fetuses with SVT showed no response and died within one to three days of treatment.
“Despite its common use in infants and children with SVT and atrial flutter, the reluctance to use this medication in pregnant women has largely stemmed from its additional class III effects, which result in its potential proarrhythmic effect associated with QT prolongation,” the authors note.
Yet, they say in their experience and in the experience of some other centers, QTc prolongation typically doesn’t occur, even at very high doses in pregnant women. Given the potential risk, however, they urge vigilance “not only in excluding maternal contraindications to sotalol treatment before initiation, but also in monitoring for electrocardiographic disturbances during loading and dose adjustments and avoiding the simultaneous use of QTc-prolonging agents, particularly certain antiemetics.”
“We did document some lesser side effects (possibly associated with the beta-blockade properties of sotalol) in some women, including lightheadedness and nausea, but none were so severe as to necessitate discontinuation of the drug,” they note.
In their paper, the researchers provide a practical algorithm for use of sotalol in cases of fetal SVT, which Dr. Hornberger said she developed in her own practice over the past 15 years.
Am J Cardiol 2012.
Published online March 22, 2012.