Clinical features

• palpitations
• dyspnoea ^b  
• chest pain
• dizziness or syncope ^c
• cardiac arrest

• any nausea or vomiting before collapse ^a  
• any cardiovascular disease, particularly   
  
  • known arrhythmias ^a  
  • ischaemic heart disease  ^d

• an irregular pulse ^b  
• cannon waves in the jugular vein ^c  
• variable amplitude of the first heart sound ^c  

Perform carotid sinus massage  ^d - it is safe if there is no bruit ^b