Clinical features

• the pain, specifically 
  • its position ^b  
  • its nature ^a  
  • any exacerbating or relieving factors ^b  
• a history of angina or myocardial infarction ^{a b} 
• cardiovascular risk factors ^d

• chest pain that is reproduced on palpation ^{a b}

• retrosternal chest pain
• pain brought on by exertion
• pain relieved in <10 minutes by rest or glyceryl trinitrate 

Men: probability of ≥50% coronary artery stenosis in at least one major artery

Age	30 to 39	40 to 49	50 to 59	60 to 69
Asymptomatic (0 symptoms)	2%	6%	10%	12%
Non-anginal chest pain (1 symptom)	5%	14%	22%	28%
Atypical angina (2 symptoms)	22%	46%	59%	67%
Typical angina (All 3 symptoms)	70%	87%	92%	94%

Women: probability of ≥50% coronary artery stenosis in at least one major artery

Age	30 to 39	40 to 49	50 to 59	60 to 69
Asymptomatic (0 symptoms)	0.3%	1%	3%	8%
Non-anginal chest pain (1 symptom)	1%	3%	8%	19%
Atypical angina (2 symptoms)	4%	13%	32%	54%
Typical angina (All 3 symptoms)	26%	55%	79%	91%

Patients at low-risk for a myocardial infarction can be assessed in a rapid evaluation unit by ^b  

• CK-MB at 0, 4, 8, 12 hours
• serial 12-lead ECGs
• clinical assessment at 0, 6, 12 hours
• exercise ECG: if all the above negative

• Look for the following risk factors:
  • pain worse than prior angina or the same as the pain associated with a prior myocardial infarction
  • systolic blood pressure <110 mmHg
  • crackles above the bases bilaterally
  • ST elevation or Q waves, not known to be old, in two or more leads
  • ST segment or T wave changes, not known to be old, indicative of myocardial ischaemia

Risk of major complications

Group a	risk of major complication at 4 days
suspected MI on ECG or suspected ischaemia on ECG and 2 or more risk factors	high
suspected ischaemia on ECG and 1 or no risk factor	moderate
one risk factor with no MI or ischaemia on ECG	low
no risk factors	very low

Note

• Elevated Chlamydia pneumoniae IgG titres are not clearly associated with an increased risk of cardiovascular disease ^b , and a three month course of antibiotics does not clearly reduce the risk. ^b