Table 1. ECG characteristics of wild-type (WT) and Scn5a ^+/− mice with mild and severe phenotype.

	n	Age (weeks)	RR (ms)	P (ms)	PR (ms)	QRS (ms)	QT (ms)	QTc
WT	16	11±0	128±3	15±0	35±1	14±1	64±1	58±1
	14	31±0	122±3	16±1	34±1	16±1	60±2	54±1
	14	50±1	122±3	16±1	35±1	16±1	58±1	53±1
	12	81±3	115±1§§§	15±1	34±1	16±1	58±1§	54±1
Mild Scn5a +/−	20	12±1	135±3	18±1**	39±1***	15±0	67±1	58±1
	16	31±0	127±2	18±1	39±1***	18±0**§§	61±2§§	54±1§§
	16	49±1	130±3	18±0*	40±1***	18±1**§§§	61±1§§	53±1§§
	8	78±5	132±2**	19±1*	42±2***	20±2***§§§	66±2**	57±1
Severe Scn5a +/−	17	11±1	142±4***	18±0*	39±1***	22±0***†	69±1*	59±1
	17	32±0	128±2§§	19±1*	38±1***	23±0***†	63±1§§	55±1
	17	50±2	124±2§§§	18±0***	39±1***	24±0***†	62±1§§	56±1
	10	80±3	128±2*	19±1**	43±1***§§	25±1***†§§	68±2***	59±1*

Abbreviations: n, number of animals per group; RR, RR interval duration; P, P wave duration; PR, PR interval duration; QRS, QRS complex duration; QT, QT interval duration; QTc, corrected QT interval duration.

Data are mean ± sem. *, **, ***, p<0.05, p<0.01 and p<0.001 respectively versus WT (matching age); ^†, p<0.001 versus Mild (matching age); ^§, ^§§, ^§§§, p<0.05, p<0.01 and p<0.001 respectively versus youngest age in each group.