Investigations

• a blood count ^b

Why?

A high leukocyte count or low relative lymphocyte percentage make a myocardial infarction more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
central or left-sided chest pain b (pre-test probability: 18%)	myocardial infarction (CK-MB at 24 hours)	elevated leukocyte count	6.8 (4.3 to 11)	60%	0.56 (0.45 to 0.70)	11%
		decreased relative lymphocyte percentage	6.3 (4.2 to 9.4)	58%	0.46 (0.35 to 0.61)	9%