Table.

(A) Results of Conventional Active 10-min Standing Tests With and Without POTS in the 13 Selected Patients With Myalgic Encephalomyelitis, (B) Rate of Failure in Completing 10-min Standing Tests With and Without POTS

(A) Patient no.	Age/sex	With POTS		Without POTS
		No. completed	No. failed	No. completed	No. failed (CI)
1	40/M	5	0	1	2
Resting → maximum HR (standing duration)		79 → 113*		76 → 105	83 → 109 (2’)*
		81 → 115*			73 → 100 (8.3’)*
		72 → 102*
		63 → 104*
		76 → 114*
2	21/F	1	0	5	4
Resting → maximum HR (standing duration)		73 → 110*		67 → 86	64 → 77 (1’)*
				58 → 76	78 → 98 (7’)*
				59 → 83	62 → 89 (7.5’)*
				60 → 82	69 → 98 (3’)*
				58 → 85
3	46/F	1	0	3	2
Resting → maximum HR (standing duration)		71 → 105*		71 → 99	65 → 90 (7.5’)*
				62 → 87	67 → 83 (5’)*
				62 → 81
4	28/F	3	0	2	2
Resting → maximum HR (standing duration)		83 → 116*		73 → 100	68 → 91 (8’)*
		69 → 102*		73 → 99
		91 → 121*
5	32/F	2	0	3	1
Resting → maximum HR (standing duration)		62 → 92*		71 → 98	58 → 80 (5’)*
		69 → 104*		66 → 90
				63 → 89
6	33/F	5	1	3	2
Resting → maximum HR (standing duration)		45 → 93*	53 → 83 (8’)	40 → 62	42 → 67 (9’)*
		45 → 84*		46 → 73	53 → 79 (8.7’)*
		64 → 102*		52 → 78
		49 → 91*
		50 → 81*
7	25/F	3	1	1	1
Resting → maximum HR (standing duration)		65 → 97*	79 → 120 (7’)	83 → 107	86 → 108 (6’)*
		75 → 108*
		92 → 120*
8	21/F	2	1	1	1
Resting → maximum HR (standing duration)		98 → 121*	101 → 126 (5.2’)	93 → 112	81 → 96 (7.3’)*
		78 → 112*
9	22/M	1	1	1	3
Resting → maximum HR (standing duration)		58 → 92*	69 → 106 (4’, OH)	69 → 90	74 → 102 (6.2’)*
					63 → 88 (8.2’)*
					65 → 92 (8.3’)*
10	27/F	5	3	6	1
Resting → maximum HR (standing duration)		75 → 114*	81 → 118 (6’)	74 → 93	69 → 88 (3’)*
		96 → 125*	79 → 116 (5’)	73 → 102
		78 → 114*	75 → 107 (5’)	88 → 114
		84 → 114*		78 → 107
		80 → 118*		77 → 95
				76 → 90
11	23/F	1	3	1	1
Resting → maximum HR (standing duration)		68 → 105*	64 → 96 (8’)	69 → 88	65 → 92 (3’)*
			78 → 117 (5’)
			70 → 100 (5’)
12	37/F	2	3	2	1
Resting → maximum HR (standing duration)		61 → 91*	66 → 104 (7.2’)	71 → 100	64 → 91 (3.7’)*
		62 → 98*	61 → 98 (4.5’)	60 → 85
			67 → 100 (3.5’)
13	26/F	0	1	3	0
Resting → maximum HR (standing duration)			68 → 107 (7.5’, NMH)	77 → 96
				59 → 76
				63 → 86
(B) Patient no.	Rate of failure**		Total rate of failure**
	With POTS	Without POTS	With POTS	Without POTS	P value
1	0 (0/5)	67 (2/3)	0 (0/12)	44 (11/25)	<0.05
2	0 (0/1)	44 (4/9)
3	0 (0/1)	40 (2/5)
4	0 (0/3)	50 (2/4)
5	0 (0/2)	25 (1/4)
6	17 (1/6)	40 (2/5)	31 (5/16)	54 (7/13)	0.27
7	25 (1/4)	50 (1/2)
8	33 (1/3)	50 (1/2)
9	67 (2/3)	75 (3/4)
10	38 (3/8)	14 (1/7)	56 (10/18)	20 (3/15)	0.07
11	75 (3/4)	50 (1/2)
12	60 (3/5)	33 (1/3)
13	100 (1/1)	0 (0/3)

(A) *Values indicate CI. HR is given in beats/min; standing duration is given in minutes. See text for details. (B) Patients 1–5 failed exclusively during standing tests without experiencing POTS, Patients 6–9 had a higher failure rate during tests without than with POTS, and Patients 10–12 had a higher failure rate during tests with than without POTS. **The rate of failure is shown as a percentage, with the number of failures/number of 10-min standing tests given in parentheses. CI, chronotropic incompetence; HR, heart rate; NMH, neurally mediated hypotension; OH, orthostatic hypotension; POTS, postural orthostatic tachycardia syndrome.