Symptoms of sinus arrhythmia vary according to different causes, including sinus bradycardia, sinus tachycardia, sinus arrhythmia, sinus arrest, and sick sinus syndrome. Mild cases of sinus bradycardia, sinus tachycardia, and arrhythmia generally do not present noticeable clinical symptoms. However, severe cases can experience symptoms such as palpitations, fatigue, and shortness of breath. Sinus arrest and sick sinus syndrome often present more severe clinical symptoms, including not only shortness of breath but also dizziness, blackouts, fainting, and acute cerebral ischemia and hypoxia.