Investigations

Use the following clinical prediction rule to rank your patient for risk of a myocardial infarction

If clinical finding not present, go onto next question a			LR  (95% CI)	probability of MI  (95% CI)
ST elevation or Q waves in 2 or more leads, not known to be old			22  (17 to 27)	75%  (70% to 79%)
			.	.
chest pain began 48 hours ago or more	=>	ST-T changes of ischaemia or strain, not known to be old	2.0  (1.5 to 2.9)	22%  (15% to 28%)
		no changes or old	0.12  (0.076 to 0.19)	1.6%  (0.9% to 2.4%)
previous history of angina or MI	=>	ST- T changes of ischaemia or strain, not known to be old	2.6  (2.0 to 3.2)	26%  (21% to 31%)
		longest pain episode < 1 hour	0.30  (0.18 to 0.49)	4.0%  (2.1% to 5.9%)
		pain worse than prior angina or the same as a prior MI	0.92  (0.65 to 1.3)	11%  (7.6% to 15%)
.		pain not as bad	0.076  (0.019 to 0.31)	1.0%  (0.0% to 2.5%)
pain radiates to neck, left shoulder or left arm	=>	aged < 40	0.18  (0.058 to 0.57)	2.4%  (0.0% to 5.1%)
.		chest pain reproduced by palpation	0.093  (0.013 to 0.67)	1.3%  (0.0% to 3.7%)
		pain radiates to back, abdomen or legs	0.60  (0.25 to 1.5)	7.7%  (1.2% to 14%)
.		chest pain stabbing	0.13  (0.018 to 0.94)	1.8%  (0.0% to 5.2%)
		chest pain not stabbing	1.5  (1.1 to 2.0)	17%  (13 to 22%)
-
ST- T changes of ischaemia or strain, not known to be old			2.3  (1.7 to 3.3)	26%  (19% to 33%)
no changes or old			0.15  (0.099 to 0.22)	2.0%  (1.2% to 2.8%)

Why?

• A third of patients can be classified as low-risk (36%: 95% CI: 34% to 38%) - 1% will die in hospital (95% CI: 0.3% to 1.8%) and 0.4% have life-threatening complications (95% CI: 0.0% to 0.8%). ^{a b}