Contemporary maternal and fetal outcomes in the treatment of LQTS during pregnancy: Is nadolol bad for the fetus?

BACKGROUND:β-Blocker therapy, specifically nadolol, is the recommended treatment for long QT syndrome (LQTS). Previous studies assessing maternal and fetal outcomes were published before the nadolol era. OBJECTIVE:The purpose of this study was to examine contemporary maternal and fetal outcomes in the treatment of LQTS during pregnancy. METHODS:We queried the Inherited Arrhythmia Database at Cleveland Clinic and identified all pregnant patients with LQTS from January 2001 through January 2020. Collected data included use and timing of β-blockers, maternal arrhythmic events, fetal growth restriction, neonatal hypoglycemia, and bradycardia. RESULTS:Among 68 live-birth pregnancies in 31 women with LQTS (mean age 29 ± 5.9 years; mean corrected QT interval 468 ± 39 ms), there were 5 arrhythmic events in 4 mothers. All arrhythmic events occurred in the postpartum period, and there were no arrhythmic events in patients taking β-blockers. In patients diagnosed with LQTS and treated with β-blockers (n = 27 [41%]), nadolol was the most commonly prescribed agent throughout pregnancy and the postpartum period (n = 16 [60%]). The rate of intrauterine growth restriction was not significantly different in fetuses exposed to β-blockers vs unexposed (P = .08). In the postnatal period, hypoglycemia was not seen and 1 patient in the exposure group had bradycardia. CONCLUSION:Arrhythmic events were only seen in the postpartum period in those not treated with β-blockers. Events occurred as late as 9 months postpartum. β-Blocker therapy, specifically nadolol, was not associated with a higher incidence of intrauterine growth restriction. Moreover, neonatal bradycardia was rare and hypoglycemia was not observed.