Clinical features

• Detect this using simultaneous auscultation and palpation: the impulse must be at least two-thirds of systole to be called sustained. Use a tongue blade pressed over apex to produce a visual demonstration of the impulse (or S3). ^d Any increase in size can be detected by percussion ^a

Why?

A displaced apex makes left ventricular failure more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
suspected heart failure b (pre-test probability: 17%)	left ventricular systolic failure (echocardiogram)	apex displaced	16 (8.1 to 31)	75%	0.36 (0.23 to 0.55)	6%

A displaced apex or enlarged heart on percussion makes radiographic cardiomegaly slightly more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
suspected cardiomegaly a (pre-test probability: 25%)	cardiomegaly (PA chest X-ray)	apex palpable beyond midclavicular line	2.5 (1.5 to 4.2)	45%	0.53 (0.32 to 0.86)	15%
suspected cardiomegaly a (pre-test probability: 36%)	cardiomegaly (PA chest X-ray)	dull to percussion at > 10.5 cm from midsternal line	2.9 (2.0 to 4.1)	62%	0.083 (0.021 to 0.32)	4%
		dull to percussion at > 11 cm from midsternal line	8.1 (4.0 to 17)	82%	0.12 (0.049 to 0.32)	7%

Note:

• 40% to 50% of apices are not palpable ^a