Bradycardia (<60bpm)

Main differential diagnoses and typical outline evidence

Athletic heart	Suggested by: young/fit, asymptomatic.
	Confirmed by: above clinical findings.
Drugs	Suggested by: history e.g. beta blockers.
	Confirmed by: improvement when drug withdrawn.
Sinoatrial disease	Suggested by: elderly, ischaemic heart disease.
	Confirmed by: ECG: abnormal P wave or P-R interval.
	Management: OHCM p127.
Ventricular or supraventricular begemini	Suggested by: known ischaemic heart disease.
	Confirmed by: ECG: premature ectopics with compensatory pause.
	Management: OHCM p126.
Myocardial infarction	Suggested by: central, crushing chest pain (can be atypical pain).
	Confirmed by: ECG: Q waves, raised ST segments, and inverted T waves. ↑CPK and troponin.
	Management: OHCM pp120–124.
Hypothyroid	Suggested by: constipation, weight gain, dry skin, dry hair, slow relaxing reflexes.
	Confirmed by: ↑TSH, ↓T4.
	Management: OHCM p306.
Hypothermia	Suggested by: history of exposure to cold temperature and immobility.
	Confirmed by: Core temperature <35(c.
	Management: OHCM p836.