Many ICDs, including the Fortify Assura ICD, can tell the difference between an irregular fast heart rate (arrhythmia) and a normal fast heartbeat. Active people, including those with ICDs, experience normal episodes of fast heartbeat. Your ICD will be able to detect if your heartbeat is of a normal kind by sensing where in your heart the signal to beat originates. However, talk to your doctor about your activities, especially about vigorous or strenuous exercise. In general, exercise and activity are healthy parts of life with an ICD.