Table 2.

Cardiac responses

	Intellectual disability		Controls	p-value
	Down syndrome	Non-Down-syndrome
	n = 96	n = 25	n = 33
Rest
Cardiac output (l/min)	3.7 ± 0.9	5.3 ± 1.3	4.5 ± 1.0	<0.001a,b,c
Cardiac index (l/min/m2)	2.3 ± 0.5	2.8 ± 0.6	2.4 ± 0.4	<0.001a,b,c
Stroke volume (ml)	55.1 ± 13.6	68.3 ± 13.1	69.8 ± 11.8	<0.001a,c
Indexed stroke volume (ml/m2)	33.6 ± 7.5	36.4 ± 5.9	37.3 ± 5.6	0.02a
Heart rate (beats/min)	68 ± 12	78 ± 13	64 ± 12	<0.001b,c
Tilting of the legsd
Cardiac output (l/min)	4.0 ± 1.1	6.1 ± 1.5	5.0 ± 0.8	<0.001a,b,c
Cardiac index (l/min/m2)	2.5 ± 0.7	3.1 ± 0.7	2.7 ± 0.3	<0.01c
Stroke volume (ml)	58.1 ± 15.0	78.8 ± 12.5	69.9 ± 10.4	<0.001a,c
Indexed stroke volume (ml/m2)	35.7 ± 7.9	39.5 ± 6.2	38.0 ± 5.9	NS
Heart rate (beats/min)	70 ± 11	77 ± 9	72 ± 10	NS
After exercisee
Cardiac output (l/min)	4.7 ± 1.3	7.5 ± 1.7	6.8 ± 1.3	<0.001a,c
Cardiac index (l/min/m2)	2.9 ± 0.7	3.7 ± 0.8	3.7 ± 0.5	<0.001a,b,c
Stroke volume (ml)	61.8 ± 15.1	80.3 ± 13.3	85.5 ± 14.8	<0.001a,c
Indexed stroke volume (ml/m2)	37.7 ± 7.5	40.4 ± 7.7	46.3 ± 6.8	<0.001a
Heart rate (beats/min)	77 ± 10	93 ± 12	79 ± 9	<0.001a,b,c

NS non significant

^aControl versus Down syndrome patients

^bControl versus non-Down syndrome patients with intellectual disability

^cDown syndrome patients versus non-Down syndrome patients with intellectual disability

^dPerformed in 52 Down syndrome patients and 22 controls, 11 non-Down syndrome patients with intellectual disability

^ePerformed in 42 Down syndrome patients and 22 controls, 11 non-Down syndrome patients with intellectual disability