Postnatal Recurrence and Transesophageal Inducibility of Prenatally Treated Fetal Supraventricular Tachycardia.

BACKGROUND: Antiarrhythmic treatment of fetal supraventricular tachycardia (SVT) is used to prevent morbidity and mortality. The postnatal management of survivors is often arbitrary and varied.

OBJECTIVES: To examine the utility of a risk-based postnatal management strategy.

METHODS: Sixty-six prenatally treated newborns with fetal long or short VA tachycardia were reviewed. Postnatal diagnoses included AV-reentrant (AVRT), atrial ectopic (AET), and permanent junctional reciprocating (PJRT) tachycardia. Unless the SVT persisted to birth, early neonatal observation without treatment was recommended. For newborns without spontaneous arrhythmia after ≥2 days of observation, inducibility was tested by transesophageal pacing study (TEPS). Postnatal therapy was advised for spontaneous or inducible SVT. Characteristics associated with these outcomes were analyzed.

RESULTS: Twenty-eight (42%) cases experienced SVT at/early after birth, which was associated with fetal long VA tachycardia (odds ratio (OR) 6.8; 95% confidence interval (CI) 1.88-24.57; p=0.0029); delayed in-utero cardioversion with treatment (median 11 vs. 5.5 days; p<0.0001); prenatal treatment with multiple antiarrhythmics (OR 4.42; CI 1.56-12.55; p=0.0059); and postnatal AET/PJRT (OR 18.0; CI 2.11-153.9; p=0.0013). Of 38 neonates undergoing TEPS, 19 had inducible tachyarrhythmias. Recurrence of SVT during infancy or childhood was documented in 4/6 (66%) cases with SVT at birth, 8/22 (36%) with early neonatal SVT, 4/19 (21%) with inducible SVT and 0/19 (0%) untreated cases without inducible SVT (p=0.0032).

CONCLUSIONS: The postnatal risk of SVT is related to the arrhythmia mechanism and prenatal treatment response. Of newborns without spontaneous SVT, TEPS may be useful to guide the need for postnatal treatment based on SVT inducibility.