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 application is intended for adults. The heart rate of children and young people can vary a lot according to respiration (sinus arrhythmia), in which case irregular respiration has more effect on the result and a normal rhythm might look irregular.

The measurement must not be performed in the following situations: the skin on the chest is damaged in the measurement area, or the phone is connected to a charger.

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

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.

Additionally, if your resting heart rate is above 130 bpm, please wait until your heart rate is lower and repeat the measurement.
If you get two consecutive Signs of atrial fibrillation results, repeat measurement without protective casing to check if the casing disturbs the motion signals.

• Remove any auxiliary device connected to the phone that prevents phone sitting flat on the chest before taking measurement.
• If you get repeatedly unsuccessful measurements, try to remove protective casing to see if that helps.
• If you get two consecutive Signs of atrial fibrillation results, repeat measurement without protective casing to check if the casing disturbs the motion signals.
• In case, you get the No signs of atrial fibrillation result without casing and the Signs of atrial fibrillation result with casing, you shouldn’t use protective casing when taking measurements.

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.

Additionally, if your resting heart rate is above 130 bpm, please wait until your heart rate is lower and repeat the measurement.

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 prevent the use of these phone models as soon as when we have determined that the quality of the data produced by the phone model is insufficient.

Also, check Should I take measurement with or without protective casing and auxiliary devices?

The gyroscope sensor of some phones produce a very poor-quality sensor signal that is mistaken for atrial fibrillation. In some phone models rebooting the phone fixes the problem. If the measurement fails repeatedly, you can contact Precordior Ltd’s customer service by e-mail at support@precordior.com.

The best way to make sure CardioSignal will work with your phone is to install it via the application store. If you cannot find the application in the app store or it 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 or the phone model is not compatible for some other reason.

You can install the CardioSignal application for free at the Apple AppStore and Google Play store. 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 and a decent mechanical connection between the phone and the chest.

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 right 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.

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. However, CardioSignal is cost-effective, immediately ready to use and does not require any additional devices.

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?

Typical pacemakers track your heart rhythm constantly. Therefore, CardioSignal is not able to provide added value to this. In addition, holding a phone powered on close to a cardiac pacemaker can create electromagnetic interference (EMI), which may cause a malfunction in the pacemaker. For these reasons, persons who have a cardiac pacemaker may not use the application.

The intended use of CardioSignal is to detect signs of atrial fibrillation in adult population.

• CardioSignal can not detect other arrhythmias than atrial fibrillation
• CardioSignal can not detect embolism nor stroke
• CardioSignal can not detect heart attacks. If you ever experience chest pain, pressure, tightness, or what you think is a heart attack, call emergency services immediately
• CardioSignal can not detect other cardiac or cardiovascular diseases
• If you are not feeling well, or you have any symptoms, contact health care provider

There might be several reasons for this (see below). For the same reasons other email communication related to CardioSignal product might be unavailable to you too.

• The account verification email might have gone to the junk email folder. Please check your junk email folder.
• The storage quota of your email account is full. You can’t receive emails until you either free space by removing old emails, upgrade your email provider plan or use another email account.

With the latest CardioSignal 2.4.0 or newer version, it is currently not possible to access the measurement results made with the previous CardioSignal version.