A heart rate of 50 beats/minute without discomfort after quitting smoking usually does not matter. A normal adult’s heart rate is usually 60-100 beats/minute in a quiet state, and it fluctuates with age, gender, and physical activity. For example, the heart rate of children under 6 years old can be >100 beats/min. Secondly, in normal people, under the influence of emotional excitement, drinking alcohol, smoking, drinking tea and other factors, it will lead to an increase in heart rate > 100 beats / min, and cause sinus tachycardia. If the increase in heart rate occurs due to smoking, resulting in sinus tachycardia, it does not matter if the heart rate is 50 beats/minute after quitting smoking. Because the heart rate > 50 beats / min, mainly due to increased vagal tone, will not appear obvious clinical symptoms, it is recommended to observe, if necessary, can choose to atropine and other drug treatment. If the above symptoms occur, it is recommended to go to the hospital in time for early and regular treatment.