When assessing the patient with palpitation who presents to the emergency department, you need to address four questions:

• What is the haemodynamic status of the patient?
• What is the cardiac rhythm?
• Is there evidence of underlying structural or coronary heart disease, pre-excitation or channelopathy?
• What systemic factors may have triggered or exacerbated the patient's symptoms?

While taking a focused history (Tables 8.1, 8.2), check the pulse and blood pressure, auscultate the lungs and:

• Attach ECG and oxygen saturation monitors.
• Give oxygen if the patient is breathless, or if arterial oxygen saturation by pulse oximetry is <92%.
• If there is evidence of haemodynamic instability, put in an IV cannula and take blood for urgent investigation including relevant biomarkers (Table 8.3).

If there is imminent cardiac arrest, call the arrest team and manage along standard lines (see Chapter 6).

If there is a reduced level of consciousness, severe pulmonary oedema, chest pain or systolic BP is <90 mmHg:

• Record a 12-lead ECG (if possible) for later analysis (Table 8.4).
• If the heart rate is >150/min: call an anaesthetist in preparation for DC cardioversion starting at 200J (Chapter 121).
• If the heart rate is <50/min: give atropine 0.6–1.2 mg IV, with further doses at 5-min intervals up to a total dose of 3 mg if the heart rate remains below 60/min. If the bradycardia is unresponsive or recurs, use an external cardiac pacing system or insert a temporary transvenous pacemaker (Chapter 119).
• Seek advice on further management from a cardiologist.

If the patient is haemodynamically stable, there is time to make a working diagnosis and plan management.

• Complete your clinical assessment (Tables 8.1, 8.2), record a 12-lead electrocardiogram and a long rhythm strip, arrange a chest X-ray, and consider other investigations (Table 8.3).
• Carefully assess the ECG (Table 8.4).
• Are there any systemic factors which may have triggered or exacerbated the patient's symptoms (Table 8.5)?

The patient can now be placed in one of two groups:

1. Persistent arrhythmia

   Further management is determined by the type of arrhythmia and the context: see Chapters 39, 40, 41, 42, 43, 44.

   Consider if there are any systemic factors which may have triggered the arrhythmia (Table 8.5).

   Consider discharge for patients with atrial fibrillation or flutter, provided that:

   • They are haemodynamically stable (no or only mild symptoms, heart rate <100/min, systolic BP >110 mmHg).
   • No systemic trigger requiring specific treatment is apparent (e.g. sepsis).
   • Stroke/thromboembolic prophylaxis has been addressed (see Chapters 43 and 103).
   • Rate-control (rather than cardioversion) is appropriate, at least in the short term.
   • A plan of management has been agreed and follow-up arranged.

2. ECG shows sinus rhythm/sinus tachycardia

   Possibilities are a paroxysmal arrhythmia (resolved before the ECG was recorded) or palpitation due to awareness of sinus rhythm/sinus tachycardia.