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Circ Arrhythm Electrophysiol. 2013 Oct;6(5):946-51. doi: 10.1161/CIRCEP.113.000618. Epub 2013 Aug 30.

Arrhythmia phenotype during fetal life suggests long-QT syndrome genotype: risk stratification of perinatal long-QT syndrome.

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1
Department of Pediatrics, Rosalind Franklin School of Medicine and Science, North Chicago, IL.

Abstract

BACKGROUND:

Fetal arrhythmias characteristic of long QT syndrome (LQTS) include torsades de pointes (TdP) and/or 2° atrioventricular block, but sinus bradycardia, defined as fetal heart rate<3% for gestational age, is most common. We hypothesized that prenatal rhythm phenotype might predict LQTS genotype and facilitate improved risk stratification and management.

METHOD AND RESULTS:

Records of subjects exhibiting fetal LQTS arrhythmias were reviewed. Fetal echocardiograms, neonatal ECG, and genetic testing were evaluated. We studied 43 subjects exhibiting fetal LQTS arrhythmias: TdP±2° atrioventricular block (group 1, n=7), isolated 2° atrioventricular block (group 2, n=4), and sinus bradycardia (group 3, n=32). Mutations in known LQTS genes were found in 95% of subjects tested. SCN5A mutations occurred in 71% of group 1, whereas 91% of subjects with KCNQ1 mutations were in group 3. Small numbers of subjects with KCNH2 mutations (n=4) were scattered in all 3 groups. Age at presentation did not differ among groups, and most subjects (n=42) were live-born with gestational ages of 37.5±2.8 weeks (mean±SD). However, those with TdP were typically delivered earlier. Prenatal treatment in group 1 terminated (n=2) or improved (n=4) TdP. The neonatal heart rate-corrected QT interval (mean±SE) of group 1 (664.7±24.9) was longer than neonatal heart rate-corrected QT interval in both group 2 (491.2±27.6; P=0.004) and group 3 (483.1±13.7; P<0.001). Despite medical and pacemaker therapy, postnatal cardiac arrest (n=4) or sudden death (n=1) was common among subjects with fetal/neonatal TdP.

CONCLUSIONS:

Rhythm phenotypes of fetal LQTS have genotype-suggestive features that, along with heart rate-corrected QT interval duration, may risk stratify perinatal management.

KEYWORDS:

arrhythmias, cardiac; atrioventricular block; fetal; long-QT syndrome; sinus bradycardia torsade de pointes

PMID:
23995044
PMCID:
PMC4151528
DOI:
10.1161/CIRCEP.113.000618
[Indexed for MEDLINE]
Free PMC Article
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