Investigations

• myoglobin ^{b c}

Why?

An elevated myoglobin diagnoses a myocardial infarction, but normal levels cannot safely rule it out.

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
suspected myocardial infarction c (pre-test probability: 18%)	myocardial infarction (history, ECG, CK-MB act)	elevated myoglobin at 3 hours after symptom onset	34 (23 to 49)	88%	0.33 (0.28 to 0.38)	7%
		at 4 hours	26 (17 to 38)	85%	0.24 (0.20 to 0.28)	5%
		at 6 hours	26 (17 to 39)	85%	0.23 (0.19 to 0.27)	5%
		at 8 hours	25 (17 to 36)	85%	0.26 (0.22 to 0.30)	5%
		at 12 hours	23 (16 to 31)	83%	0.33 (0.28 to 0.39)	7%
		at 20 hours	13 (8 to 20)	74%	0.63 (0.56 to 0.71)	12%