A one-month-old infant was noted to have tachycardia to 280 beats per minute (bpm) by a wearable, direct-to-consumer (DTC) heart rate monitor one evening. She was sleeping comfortably when examined by her parents. After turning the device off and feeding the child, the parents reattached the monitor and once again noted tachycardia. She was then taken to the Emergency Department where they confirmed tachycardia up to 300bpm. She was subsequently diagnosed with supraventricular tachycardia and was monitored for several days in the hospital.
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Using consumer generated data to identify episodes of tachyarrhythmia
With advances in DTC monitoring available in many big box stores, parents may be more aware of anomalies in their infants’ vital signs. But this abundance of user-generated data may also give physicians insight about just what happens while babies sleep.
The findings of one such study, using data generated from DTC monitors, suggest that the incidence of tachyarrhythmia was 2.5% in the first year of life, which is dramatically higher than previous estimates of 0.1 – 0.25%. The research was recently published by The Journal of Pediatrics.
Led by electrophysiologist Peter Aziz, MD, of Cleveland Clinic Children’s, the research team analyzed de-identified data generated by consumers using the Owlet Smart Sock (OSS) for heart rate and oxygen saturation monitoring. The OSS is a wireless pulse oximeter, embedded within a sock, which is intended to be worn by healthy infants while sleeping. Using a Bluetooth connection, the sock sends data to a base station, which pushes the data to the cloud, where it is aggregated and delivered to parents via a mobile app. If the infant’s vitals are abnormal, the base station and app will sound a notification.
For the purposes of this study, investigators defined tachyarrhythmia as a heart rate of > 240 bpm for at least 60 seconds with a > 60 bpm deviation from the baseline heart rate. Infants were included if they lived in the U.S., were born between February 1, 2017 and February 1, 2019, and had a minimum of 24 cumulative hours of monitoring data. Accounting for these criteria, a total of 100,949 infants were included, with over 200 million total monitored hours.
The team identified 5,070 episodes of tachyarrhythmia in 2,508 (2.5%) infants, a detection rate of approximately 10x that of previously published reports. The average heart rate of these episodes was 267 bpm, with an average duration of 7.3 minutes. Six percent of all episodes lasted longer than 45 minutes. Tachyarrhythmia was more common in females (2.7% vs. 2.0%, P < 0.001) and infants with congenital heart disease (4.0% vs. 2.4%, P = 0.015). The median age at the time of the first episode was 36 days.
Infant arrhythmias may be asymptomatic at first
“Tachyarrhythmias in infants can be difficult to identify clinically, as many patients remain asymptomatic. Even when arrhythmia persists for hours, the symptoms of heart failure may be missed because they can be non-specific clinical findings such as fussiness or poor feeding,” says Dr. Aziz.
Indeed, the first clinical signs of arrhythmia in infants may be profound, resulting in cardiovascular decompensation from impaired cardiac function. The insidious nature of tachyarrhythmias highlights the importance of early detection and treatment. Unfortunately, accurate assessment of the prevalence of tachyarrhythmia in the infant population has been elusive. This study suggests that the prevalence of tachyarrhythmias in this infant population is much higher than previously thought, with a surprisingly high proportion of events that sustain for several minutes. Though the clinical implications of this study are yet to be determined, this study suggests that many infants have arrhythmias that go largely undetected.
High number of false alarms
With perhaps an abundance of caution, the study investigators applied rather strict criteria in their data set to avoid false alarms, or detections of tachycardia from the monitor that did not in fact represent arrhythmia. Before applying their strict definition of tachycardia, investigators identified 14,083 alarms that were triggered for heart rates over 240 bpm that lasted more than 10 seconds. Their more specific definition of tachyarrhythmia reduced the number of suspected episodes by 74%.
“Parents may be distressed by alarms. The clinician’s role in this context is to provide support and expertise,” Dr. Aziz advises. “At the very least, as a medical community managing infants, we must be aware of the rate of detection by these devices. These data provide evidence that a large proportion of these alarms are likely to represent clinical arrhythmia. This awareness, in conjunction with the importance of vigilance for symptoms such as fussiness, lethargy, pallor, vomiting and poor feeding, will provide a reasonable safety net for our infant population.”