Table 2.

Baseline Characteristics and Response to Standing, LQT1 Versus LQT2

	LQT1 (n = 31)	LQT2 (n = 28)	p Value
Age, yrs	33 ± 15	30 ± 13	0.400
Female	21 (68)	23 (82)	0.243
Baseline heart rate, beats/min	67 ± 11	62 ± 9	0.051
Baseline QT interval, ms	445 ± 42	455 ± 45	0.375
Baseline QTc interval, ms	468 ± 39	460 ± 39	0.445
Response to standing
Increment in heart rate, beats/min	24 ± 10	26 ± 11	0.474
Maximal heart rate, beats/min	95 ± 14	91 ± 13	0.053
Δ QT during maximal tachycardia, ms	−8 ± 32	21 ± 28	0.001
Δ QTc during maximal tachycardia, ms	67 ± 41	114 ± 42	<0.001
Δ QTc during longest QT interval, ms	80 ± 50	126 ± 49	0.001
Δ QTc during maximal QT interval stretching, ms	73 ± 43	119 ± 48	<0.001

Data are mean ± SD or n (%).

Abbreviations as in Table 1.