Cardiac arrhythmias can be broadly classified based on the heart rate as bradyarrhythmia (<60 bpm) and tachyarrhythmia (>100 bpm). Physiological bradycardia can often be found in athletes whilst pathological bradycardia signifies sinus node or conduction pathway abnormalities, which may or may not be associated with drugs, autonomic or endocrine dysfunction. Acute management of arrhythmias depends on the haemodynamic status of the patient and the type of arrhythmia. Patients who exhibit adverse features will require urgent treatment to resolve the arrhythmia. Narrow complex and broad complex tachyarrhythmias without adverse signs are managed differently in the acute setting. Most sinus tachycardias are related to underlying causes and will resolve once the cause is rectified. Broad complex tachycardias are due to a number of underlying rhythms. In the long term, implantable cardiovertordefibrillator (ICD) insertion is beneficial for patients who have structurally abnormal hearts with ventricular arrhythmias.