Apple Watch ECG useful for children during cancer therapy

Deepak Gupta June 4, 2022
Updated 2022/06/04 at 7:44 PM

The ECG sensor is undoubtedly one of the biggest assets of the Apple Watch. Reliable, useful and that provides users with an important tool in the surveillance of certain cardiac conditions. Several studies have already confirmed the usefulness of the ECG of a lead and it has already been pointed out as a fundamental element in saving human lives. Now, the Murdoch Childrens Research Institute in Australia has launched a new study to validate the smartwatch ECG application of American technology in children during and after cancer therapy.

The various data collected by the watch could be very important to help take care of children while fighting the terrible disease.

The Murdoch Children's Research Institute (MCRI) is the largest child health research institute of Australia and the world's top three child health research institutes for the quality and impact of their research.

The prospective study in pediatric patients, adolescents and young adults aged between 7 and 18 years, aims to validate the using the Apple Watch's electrocardiogram (ECG) function to measure prolonged QT during and after cancer therapy.

What is QTc and how can it be verified with Apple Watch

The QT interval is a measure that represents the total time from ventricular depolarization to complete repolarization. This process starts at the beginning of the Q wave and extends to the end of the T wave.

Because we have the need to create a number for the normal, a mathematical formula was created, known as Bazett's formula. This is designed to correct the patient's heart rhythm. The "c" in QTc stands for "corrected". If you plug some variables into a QTc formula, you will get a numerical result.

This number is then compared with the two normal values ​​(male 0.39, female 0.41). This method allows 12-lead computers to quickly calculate QTc and print it on the ECG record. It also allows paramedics to quickly assess the QT interval.

Each square corresponds to 40ms.

A smartwatch can feasibly and reliably assess the QTc interval

For the present case, the Prolonged QT is the medical term for a prolonged interval between contraction of the heart and relaxation. This condition can increase a person's risk of experiencing abnormal heart rhythms and sudden cardiac arrest.

The reliability of QTc measurements between standard and smartwatch ECG was also demonstrated with an analysis Bland-Altman using different formulas. These data show that a smartwatch can feasibly and reliably evaluate the QTc interval.

TIP: If you have never checked your QTc before, you can easily do so using the QTc-Calculator application on your Apple Watch. The application is free and available in the App store.

Practical tip: what are the normal values ​​of corrected QT interval (QTc)?

  • Men – Normal QTc between 340 ms and 450 ms
  • Women – Normal QTc between 340 ms and 470 ms

This application allows doctors to quickly calculate QTc. You can enter heart rate or RR interval duration and QT interval duration.

The RR interval is the distance between two successive R waves (including an R wave). At the sinus rhythm the RR interval must be constant. The RR interval is measured from the beginning of one R wave to the beginning of the next R wave. Its duration depends on the heart rate.

In regular rhythm electrocardiograms, it can be calculated knowing the heart rate value (see RR interval calculation from heart rate">RR interval calculator).

There will be up to three results for the QTc, using three of nine different formulas: Bazett, Fridericia, Framingham, Hodges, Goto, Mayeda, Kawataki, Rautaharju a, and formula b.

RR interval or heart rate and QT estimates depending on heart rate are also determined.

What are the goals of the MCRI in the Apple Watch study?

This new Australian study will attempt to understand the following:

Primary objective:

  • Evaluate the results between QTc measured using 12-lead ECG and with the Apple Watch using mean absolute error calculations.

Secondary Objectives:

  • Calculate sensitivity and specificity for measuring prolonged QTc using Apple Watch;
  • Calculate the interobserver variability between the two healthcare professionals' QTc readings.

The central hypothesis is that the use of technology wearable The existing framework for monitoring QTc prolongation has the ability to achieve routine monitoring strategies in large populations, which may facilitate ambulatory care.

Using the Apple Watch to monitor prolonged QTc in this study improves patient outcomes by facilitating real-time monitoring of potential irregularities, widespread surveillance, detection and faster initiation of treatment solutions.

The app together with the device (Apple Watch) will record a V1 (left wrist) or V2 (left ankle) ECG reading. These measurements will be performed on Day 1 and Day 4 of the hospital stay.

In summary, with the passage of time and with more research, it is clear that the Apple Watch has become not only an aid device for the user to control their well-being, but also a tool for constant monitoring of the person's health. In addition, this type of technology, not only from Apple but also from several other manufacturers, can help to constantly monitor people with some disease scenario and who need constant surveillance.

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