Table 1.

Clinical characteristics of the LQT2 mutation carriers with normal QTc and genotype-negative family members.

Clinical characteristics	Number of missing values	LQT2 Normal QTc	Number of missing values	Genotype-negative controls	p-value
Number		154		1007
Male, n(%)	0	67 (44)	0	414 (41)	0.574
Age at ECG, years	0	41±15	0	41±15	0.837
Pore mutation	1	23 (15)	0	0	-
Syncope <18 years, n(%)	0	23 (15)	0	62 (6)	<0.001
Electrocardiography
RR, ms	0	959±174	0	893±166	<0.001
PR, ms	1	160±23	32	161±28	0.320
QRS, ms	0	84±14	0	85±14	0.438
QTc, ms	0	436±23	0	417±26	<0.001
Tpeak-Tend lead II, ms	4	94±31	3	86±21	0.004
Abnormal T-wave in V5 or II	12	55 (39)	61	64 (7)	<0.001
Treatment
Beta-blockers	0	81 (53)	0	187 (19)	<0.001
ICD	0	25 (16)	0	17 (2)	<0.001
Cardiac events ≥18 years
Syncope	0	41 (27)	0	133 (13)	<0.001
ACA	0	4 (3)	0	3 (0)	0.008
SCD	0	5 (3)	0	0 (0)	<0.001
Appropriate ICD shock	0	1(1)	0	4 (0)	0.510

Data are presented as means ± standard deviations or number (%)

* T-wave characterization was missing in 12 LQT2 patients (8%) and 61 control subjects (6%)