Sudden death does not usually occur with a heartbeat of 90 beats per minute. However, if the elderly or patients with poor heart function have difficulty tolerating it, sudden death may occur, but is less common. A normal adult heart rate is between 60 and 100 beats/min, but whether a heartbeat of 90 beats/min is normal depends on the circumstances. If the previous heart rate has been in the 80-90 beats per minute range, the heart rate is normal. If the previous heart rate was around 60 beats per minute and suddenly reaches 90 beats per minute with panic, fast heartbeat and other discomfort, the heartbeat is abnormal and the specific cause needs to be determined. If it is caused by drinking alcohol, strong tea, emotional excitement or after exercise, no special treatment is needed and the patient can recover with rest. If you still feel uncomfortable with your heart after excluding the above causes, you should be admitted to the hospital for examination to clarify the cause, which may include hyperthyroidism, anemia, and other diseases that require symptomatic treatment. However, sudden death usually does not occur. When you feel panic, chest tightness and other uncomfortable symptoms, even if your heart rate is normal, you need to pay attention to it. Various tests such as electrocardiogram and cardiac ultrasound can be performed to rule out the possibility of pathological diseases.