ECG education

Sick sinus syndrome

Vivienne Miller



An elderly woman’s ECG suggests she has sick sinus syndrome. In what ways may her ECG be abnormal, what are the causes and how might she be managed?

Key Points

  • Sick sinus syndrome is group of disorders of cardiac rhythm that include sinus bradycardias, sinus pauses and sinus arrest. They may also include supraventricular tachycardias and tachy-bradycardia syndrome.
  • Sick sinus syndrome may be asymptomatic, but symptoms are mostly caused by a reduced cardiac output, such as intermittent severe fatigue, flushing, light headedness, dizziness, palpitations, shortness of breath with exercise, generalised weakness and intermittent chest discomfort.
  • Signs include presyncope and syncope, intermittent confusion, intermittent worsening of stable congestive cardiac failure, frequent episodes of angina, and transient ischaemic attacks or stoke if there is pre-existing vascular disease.
  • The condition is idiopathic most likely caused by degeneration of the cardiac electrical pathways and sinus node due to age, but beta blockers, calcium channel blockers and antiarrhythmic drugs are also frequently implicated.