Abstract 20644: Comparison of Efficacy and Safety of First-line Transplacental Treatment of Fetal Supraventricular Tachycardia (SVT) and Atrial Flutter (AF) with Sotalol, Flecainide and Digoxin
Background: Fetal tachyarrhythmias may result in low cardiac output and death. Consequently, treatment is offered to most affected pregnancies. We compared 3 commonly used drugs in controlling fetal SVT/AF.
Methods: We reviewed 159 consecutive referrals to our centers since 1998 with fetal SVT (n=114) and AF (n=45). Of them, 111 (SVT: n=75; 77% AF: n=36; 80%) were treated non-randomly with flecainide±digoxin (N=38), sotalol±digoxin (N=56), or digoxin (N=17) as 1st line agents. Kaplan-Meier estimates were used to determine treatment effects over time. Conversion to sinus rhythm within ≤5 days was defined as early treatment success.
Results: The table shows details of the 111 treated fetuses. Fetal hydrops was associated with treatment failure (p<0.03; HR 1.8) and in-utero death (p<0.002; HR 4.7). Compared to SVT, AF was more difficult to convert to sinus rhythm prior to delivery (p=0.02; HR 2.2), independent of the choice of therapy. If incessant AF persisted to day 5 (N=24), a decline in heart rate was observed with flecainide (median: −50 bpm) but not with sotalol (−3 bpm; p=0.008). Sotalol was also less likely to convert SVT to a normal rhythm, compared to flecainide or digoxin (p<0.05). Freedom from arrhythmia on maintenance therapy was 93% and 90% at 1 and 3 months, respectively. Overall mortality was 8%, but in only 4% (3/38 (8%) flecainide±digoxin; 2/56 (4%) sotalol±digoxin; 1 (2%) no treatment) this was related to the arrhythmia. Post-hemorrhagic hydrocephalus without neurological sequels occurred in 1% (2/159 cases). None of the mothers or fetuses experienced severe treatment-related side effects.
Conclusions: In the absence of hydrops, fetal AF/SVT was associated with a low morbidity and mortality despite modest early treatment success rates. Flecainide was superior in converting SVT to a normal heart rate and in slowing AF to better tolerated ventricular rates and therefore should be first considered to treat relevant tachyarrhythmias.
- © 2010 by American Heart Association, Inc.