A system for determining a probability of arrhythmia for a person, comprising - means for measuring heartbeat interval of the person for a period of time, the means for measuring heartbeat interval is selected from electrical measurement means and optical measurement means, and the means for measuring heartbeat interval is a wearable means selected from a wristband, an ankleband, a ring and a chest belt; - means for measuring an electrocardiogram of the person; - a user interface for providing information and alerts; and - a processor configured to - analyse the measured heartbeat interval to determine a probability of having arrhythmia for the person; - generate an alert to the user interface, if the probability exceeds a predetermined threshold value, to alert the person to measure the electrocardiogram with the means for measuring an electrocardiogram; - analyse the measured electrocardiogram to determine if the probable arrhythmia is confirmed; and - indicate the confirmed arrhythmia to the person via the user interface; wherein the processor, the user interface, and the means for measuring the electrocardiogram, are arranged in a portable computing device, and the portable computing device being separate from, and communicably coupled to, the wearable device via a short-range wireless communication network; and wherein the configuration of the processor to analyse the measured electrocardiogram to determine if the probable arrhythmia is confirmed comprises analysing if the electrocardiogram is in sync with the measured heartbeat interval. - means for measuring heartbeat interval of the person for a period of time, the means for measuring heartbeat interval is selected from electrical measurement means and optical measurement means, and the means for measuring heartbeat interval is a wearable means selected from a wristband, an ankleband, a ring and a chest belt; - means for measuring an electrocardiogram of the person; - a user interface for providing information and alerts; and - a processor configured to - analyse the measured heartbeat interval to determine a probability of having arrhythmia for the person; - generate an alert to the user interface, if the probability exceeds a predetermined threshold value, to alert the person to measure the electrocardiogram with the means for measuring an electrocardiogram; - analyse the measured electrocardiogram to determine if the probable arrhythmia is confirmed; and - indicate the confirmed arrhythmia to the person via the user interface; - analyse the measured heartbeat interval to determine a probability of having arrhythmia for the person; - generate an alert to the user interface, if the probability exceeds a predetermined threshold value, to alert the person to measure the electrocardiogram with the means for measuring an electrocardiogram; - analyse the measured electrocardiogram to determine if the probable arrhythmia is confirmed; and - indicate the confirmed arrhythmia to the person via the user interface; the processor, the user interface, and the means for measuring the electrocardiogram, are arranged in a portable computing device, and the portable computing device being separate from, and communicably coupled to, the wearable device via a short-range wireless communication network; and wherein the configuration of the processor to analyse the measured electrocardiogram to determine if the probable arrhythmia is confirmed comprises analysing if the electrocardiogram is in sync with the measured heartbeat interval.