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. Author manuscript; available in PMC: 2015 Jan 1.
Published in final edited form as: Am Heart J. 2013 Oct 22;167(1):10.1016/j.ahj.2013.10.009. doi: 10.1016/j.ahj.2013.10.009

Table II.

Summary of ECG intervals

Interval All
Men
Women
Heritability
N* Mean (SD) N* Mean (SD) N* Mean (SD) h2 (SE)†
QT, milliseconds 4062 413.8 (31.1) 1531 408.5 (30.6) 2531 417.0 (30.9) 0.43 (0.07)
QTc, milliseconds 4062 425.6 (26.3) 1531 414.7 (25.8) 2531 432.1 (24.3) N/A
JT, milliseconds 4062 321.0 (30.9) 1531 312.2 (29.8) 2531 326.3 (30.3) 0.42 (0.06)
JTc, milliseconds 4062 332.8 (27.0) 1531 318.4 (25.6) 2531 341.5 (24.0) N/A
QRS, milliseconds 4212 92.9 (11.7) 1578 96.5 (12.3) 2634 90.7 (10.8) 0.33 (0.06)

h2 = heritability coefficient; JTc = QTc – QRS; N/A = not applicable.

*

Total number in each group with an SCN5A-1103S/1103Y genotype after the interval-specific exclusions.

†

The heritability was estimated in 1494 JHS participants in 266 families using variance components methods implemented in SOLAR34 and represents the fraction of remaining variation (after adjustment for covariates) explained by additive genetic factors.