Frequently Asked Questions

The CardioSignal application sends the data collected by the motion sensors of the smartphone to the Precordior cloud service. The data is analyzed in the cloud service, and the results are sent back to the smartphone. Data analysis utilizes, e.g., machine learning and clinical research data collected from over 300 patients by the University of Turku, Finland.

The measurement utilizes the motion sensors of the smartphone to measure the movement of the heart. Because of this, any activities that may interfere with the measurement process need to be stopped for the duration of the measurement. Here are short instructions on how to take a measurement:

Things to take into consideration before a measurement:

• Atrial fibrillation is the most common cardiac arrhythmia, and it may occur occasionally or in a sustained manner. In order to detect possible atrial fibrillation with the CardioSignal application according to the intended use, a measurement must be taken twice in a 24-hour period, e.g., once in the morning and once in the evening.
• Do not exercise before taking a measurement.
• Your heart rate range must be 30–160 beats per minute. Otherwise, the application displays a failed result for that measurement.
• If you have a pacemaker, do not use the application.

Taking a measurement:

• Remove any thick clothing, such as a jacket.
• Lay on your back and relax.
• Press Start.
• Place the phone in the middle of your chest with the screen facing upward.
• Keep your hands in a relaxed position at your sides.
• There is a 10-second countdown before the 60-second measurement begins.
• Do not talk, cough, or move during the measurement.
• After the measurement ends, the application plays a sound and vibrates lightly.
• Following these signals, you can remove the smartphone from your chest.
• When the analysis is complete, the application displays the results.

Atrial fibrillation is the most common cardiac arrhythmia, and it may occur occasionally or in a sustained manner. In order to detect possible atrial fibrillation with the CardioSignal application according to the intended use, a measurement must be taken twice in a 24-hour period, e.g., once in the morning and once in the evening.

It is important to repeat the measurement after atrial fibrillation has been detected. Repeat the measurement at least twice. Contact a doctor if atrial fibrillation is detected repeatedly.

Make sure you have taken the measurement correctly. If your resting heart rate is low (under 50 bpm), the irregular chest movement caused by breathing may interfere with the measurement. In this case, you can try holding your breath for 10 to 20 seconds during the measurement.

If you suffer from paroxysmal atrial fibrillation, the CardioSignal application can be used to detect when an episode of atrial fibrillation is taking place.

If you suffer from permanent atrial fibrillation, the CardioSignal application does not offer additional information on your condition. In this case, it has already been established that you suffer from atrial fibrillation.

Adolescents and children: The CardioSignal application is not intended for adolescents or children. They often have natural heart rate variability, which the application may interpret as atrial fibrillation.

Adults: For adults, a low resting heart rate (50 bpm or lower) and the irregular chest movement caused by breathing may interfere with the results. You can try holding your breath for 10 to 20 seconds during the measurement process to see if positive atrial fibrillation readings persist.

Problem with sensors: Some Android devices may use sensors that produce extremely poor-quality data which cannot be used to detect atrial fibrillation reliably. We aim to update the list of such devices in the Google Play store and this FAQ section.

The gyroscope sensor of the Huawei P-Smart FIG-LX1 phone produces a very poor-quality sensor signal that is mistaken for atrial fibrillation. We do not recommend using the CardioSignal application on the phone model in question.

The best way to make sure CardioSignal will work with your phone is to install it via the application store. If the application store does not allow you to download the application, it may be because the operating system of your phone is too old or your phone is missing the required motion sensors.

You can install the CardioSignal application for free at the Apple AppStore and Google Play store. You can try the measurement feature 20 times at no cost. You can view the minimum requirements for the phone in the download section.

The gyroscope and the accelerometer are motion-reactive sensors with three axes, and they are common in modern smartphones. The gyroscope measures rotation, and the accelerometer measures acceleration.

The sensitive motion sensors of the phone are able to detect the small vibrations in the chest area caused by the pumping motion of the heart, and CardioSignal is able to interpret these vibrations to determine how the heart is functioning. The application needs the data collected by both sensors to function in a reliable way.

You can install the CardioSignal application for free at Apple AppStore and Google Play store. You can try the measurement feature 20 times at no cost before deciding if you want to subscribe to the service. Installing the application and the 20 free measurements do not cost anything, but you will need to create a username to be able to use the measurement function.

Yes! You can try the CardioSignal application’s measurement feature 20 times at no cost. You can install the CardioSignal application for free at Apple AppStore and Google Play store. Installing the application and the 20 free measurements do not cost anything.

You can order the measurement function of the CardioSignal application by using the Apple or Google payment system. There are three different subscription periods and prices available: one month, three months, and one year.

The subscription gets renewed automatically depending on the subscription period selected. For example, a one-month subscription renews every month, and is billed before the beginning of each new subscription period. A 1-month subscription costs 7.99€, a 3-month subscription costs 14.99€, and a 1-year subscription costs 49.99€.

The prices were last updated on 30 January 2020, and existing subscriptions are automatically updated according to the protocols of the Apple and Google payment systems.

You can pay the measurement function of the CardioSignal application in GooglePlay or AppStore application stores. The order is always managed through the application store.

Payment options in application stores are:

• A credit or debit card, in which case the card information is linked to the application store account information
• Redeem a GooglePlay or AppStore gift card, gift code, or promotional code
• Paypal account
• Carrier billing is possible in some countries.

You can cancel your CardioSignal application subscription at any time. The way to do this is slightly different in iPhone and Android phones.

iPhone: You can terminate your subscription or change it in the Settings menu. Open Settings -> iTunes and App Store -> click on Apple ID -> View Apple ID -> Subscriptions -> CardioSignal -> Cancel subscription.

Android: You can terminate your subscription or change it in the Google Play application. Open Google Play -> Open menu (found in the upper left corner) -> Choose subscriptions -> CardioSignal -> Cancel subscription.

You can restore your CardioSignal application subscription, e.g., after re-installing the application. The way to do this is slightly different in iPhone and Android phones.

iPhone: Make sure you are using the same Apple ID as when you last used the application. Log into the CardioSignal application using your CardioSignal username. Choose ‘Subscription’ and ‘Restore subscription’. The subscription is restored, and you can continue taking measurements.

Android: Make sure you are using the same Google account as before. Log into the CardioSignal application using your CardioSignal username. The subscription is restored automatically, and you can continue taking measurements.

You can also activate the CardioSignal application measurement function using an online service. You can purchase the activation from Precordior Ltd. partners. At the moment, pharmacies of the Avainapteekit pharmacy chain in Finland are selling the CardioSignal activation. Activation instructions are always sent by email, and the activation happens only via an online service, unlike in earlier versions where the activation had to be done in the application.

The CardioSignal application sends all measurement data to the Precordior cloud service, where the data is encrypted and stored in our database. The CardioSignal application may save data such as measurement history in the cache of the application, but the data is almost always searched from the cloud service. The cache is used to speed up, e.g., the startup of the application. The application also saves certain user settings, such as sound and vibration settings.

If you delete your CardioSignal account from the application settings, all of your personal data is deleted, but your measurement results and sensor data remain in our database. This means you cannot be linked with any of the data in our database, such as measurement data, in any way after your account has been deleted. We use measurement data and measurement results to improve our service, as stated in the Terms of Use, which you accept during the application’s setup process. Besides improving our service, we may use the data collected from you, e.g., in publications.

It is important to us to keep your data safe, and that is why we take data security matters seriously. All data sent to the Precordior cloud service are transferred via an encrypted HTTPS connection, and all of our databases are encrypted. The servers used to produce the database and service are connected to a private network that cannot be directly accessed on the internet.

With passwords, we are using the PBKDF2 algorithm with SHA256 hash encryption and the “stretching mechanism” of the password, as recommended by NIST. The databases of the Precordior cloud service use an encryption algorithm that is in compliance with standard AES-256 to encrypt both the active database and the daily back-ups.

The CardioSignal technology is based on gyrocardiography technology, patented by us, which utilizes the gyroscope and accelerometer of a smartphone to measure heart movements. Our technology has been clinically tested on over 300 patients in Finnish hospitals. The result of our research is that the sensitivity of the CardioSignal application (signs of atrial fibrillation detected) is 95.3% and the accuracy (no signs of atrial fibrillation) is 96.0%. These results were published in May 2018 in the esteemed Circulation, the American Heart Association Journal, the world’s pre-eminent cardiology publication.

It is true that there are also other products for detecting atrial fibrillation available, based on different kinds of technology, but the accuracy and reliability of the measurements are clearly inferior, and they can take up to 50% longer to take a measurement than the CardioSignal application.

CardioSignal does not require expensive additional devices to function, and nearly everyone has a compatible smartphone in their pocket. The Apple Watch does not measure your heart all the time, either. In order to detect atrial fibrillation or take an ECG using an Apple Watch, you need to be still and have a pulse of 50–230 bpm.

To start using CardioSignal, all you need to do is install the free application in the Apple AppStore or Google Play store. You can try the measurement feature 20 times at no cost before deciding whether you want to subscribe.

Yes, you can. You can view your earlier measurement results by using the same CardioSignal account. If you have activated the measurement function by using an activation code, you can also use the same username in your new phone.

If you have purchased a one-month, three-month, or one-year subscription with your old phone, e.g., an iPhone, the subscription will not work in an Android phone, and it won’t work if you switch from an Android phone to an iPhone, either. In this case, you will need to cancel your old subscription and purchase a new subscription using the new phone. Please note that if you do not cancel your old subscription, it will renew automatically. See the question How can I cancel my subscription?

Persons who have a cardiac pacemaker may not use the application. Holding an activated phone close to a cardiac pacemaker can create electromagnetic interference (EMI), which may cause a malfunction in the pacemaker.