Fetal heart rate and arrhythmia profile predicts long QT syndrome (LQTS) genotype : Results of an 8-center international study

• Objective: 1. Determine if fetal heart rate (FHR) predicts LQTS across gestational ages (GA). 2. Ascertain genotype specific effects on FHR and rhythm.Study Design: FHR and rhythm data were ascertained from fetuses with maternal or paternal LQTS1, LQTS2 or LQTS3 genotype at 8 international centers. We reviewed obstetrical history including maternal beta blocker (BB) use. At each obstetrical visit, FHRs were calculated from an average of 3 heart beats (ultrasound) or 3 10-second periods of FHR auscultation (Doppler monitor) measured during fetal quiescence. Postnatal genetic testing was performed by commercial laboratories. We compared FHR in the 1st, 2nd and 3rd trimesters between fetuses with (LQTS+) and without (LQTS-) the family mutation by t-test. Differences in FHR between LQTS genotypes were compared by ANOVA. Log FHR was analyzed by a linear mixed effect model with GA as the continuous variable and adjusting for maternal BB use. The predictive ability of FHR to discriminate LQTS+ from LQTS- was addressed by ROC analysis, evaluating the magnitude of FHR (intercept) and change in FHR (slope) across GA.Results: Data were available on 51 LQTS+ and 27 LQTS-. Mean FHR differed between LQTS+ and LQTS- fetuses in 2nd and 3rd but not in the 1st trimesters (Table). The magnitude of FHR change in 2nd and 3rd trimesters discriminated LQTS + from LQTS- (both, p<0.05); with AUC of 0.81. FHR effect was most pronounced for LQTS1 and differed significantly between genotypes. LQTS3 did not exhibit a FHR effect at any GA. Only LQTS2 had signature LQTS arrhythmias (2◦ AV block and/or torsade de pointes). Maternal BB had no significant effect on FHR.Conclusion: In this study with a preponderance of LQTS1, FHR discriminated LQTS+ from LQTS- fetuses in the 2nd and 3rd trimesters. LQTS genotype appears to affect the fetal presentation of LQTS. These findings provide insight into the natural history of LQTS before birth and may facilitate early detection of LQTS1 and LQTS2 fetuses.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Reproduktionsmedicin och gynekologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Obstetrics, Gynaecology and Reproductive Medicine (hsv//eng)

Publication and Content Type

vet (subject category)

art (subject category)