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Long QT and Hearing Loss in High-Risk Infants Prospective Study Registry
Arnold L Fenrich1, Daniel P Shmorhun1, Gregory C Martin2,3
1Children's Cardiology Associates, Austin, TX, USA.
Insights
Five percent of infants with sensorineural hearing loss showed prolonged QTc intervals on ECGs. Genetic testing may be more effective than electrocardiograms for identifying at-risk infants with hearing loss.
Area of Science:
- Pediatrics
- Cardiology
- Genetics
Background:
- Sensorineural hearing loss (SNHL) in infants can be associated with cardiac conditions.
- Prolonged QTc interval on an electrocardiogram (ECG) is a risk factor for potentially fatal arrhythmias.
Purpose of the Study:
- To determine the prevalence of prolonged QTc intervals in infants diagnosed with SNHL.
- To explore the utility of ECGs and genetic testing in this population.
Main Methods:
- Prospective study of 40 healthy term infants with SNHL.
- ECG performed between 2-6 months of age.
- 1-year follow-up for hearing and cardiac status; family history and genetic testing obtained when indicated.
Main Results:
- Two of 40 infants (5%) had QTc > 450 ms; both had mild bilateral SNHL and no identified LQTS mutation.
- 38 infants had QTc ≤ 450 ms.
- One infant with severe SNHL and a family history of cardiomyopathy/arrhythmias was found to have a KCNQ1 gene mutation.
Conclusions:
- A small percentage of infants with SNHL exhibit prolonged QTc intervals.
- Genetic testing may be a more comprehensive approach than ECGs for identifying cardiac risks in infants with SNHL, especially with a family history.
Abstract:
The objective of this study is to determine the prevalence of an abnormal electrocardiogram showing a prolonged QTc greater than 450 ms in infants with unilateral or bilateral sensorineural hearing loss. We conducted a prospective study of healthy term infants (≥37 weeks gestational age) who failed their newborn auditory brainstem response hearing screen, were seen by an audiologist and diagnosed as having sensorineural hearing loss during follow-up to 1 year of age. In infants with a diagnosis of hearing loss, we collected a detailed family history and performed an ECG between 2 and 6 months of age. We obtained follow-up for 1 year by calling the parent requesting the hearing and cardiac status of their child. Two of the 40 infants with sensorineural hearing loss (5%) had a QTc greater than 450 ms. Both had mild bilateral hearing loss and genetic testing did not identify a known mutation for long QT syndrome. The remaining 38 infants had QTc intervals of ≤ 450 ms. One patient diagnosed with bilateral severe sensorineural hearing loss had a normal ECG (QTc = 417 ms). Several months after the ECG was performed, the infant's mother contacted the study cardiologist after she learned that the infant's maternal grandmother was diagnosed with a cardiomyopathy and arrhythmias. Genetic testing was recommended even though the child was asymptomatic and was positive for a pathogenic mutation in the KCNQ1 gene. We speculate that molecular genetic testing in infants with hearing loss may become the standard of care rather than targeted electrocardiograms.Clinical Trial Registration NCT02082431 https://www.clinicaltrials.gov/ct2/show/NCT02692521?cond=NCT02692521&rank=1 .
