. Author manuscript; available in PMC: 2017 Jan 1.

Published in final edited form as: Heart Rhythm. 2015 Aug 31;13(1):190–198. doi: 10.1016/j.hrthm.2015.08.037

Table 3.

Percentage of QTc prolongation (median values) in LQTS subjects between two periods of the day: 3–4AM and 3–4PM. Prolongation percentage is defined as the percentage of heart beats with QTc above the gender-specific threshold during the given hours. Periods starting at 3AM and 3PM were chosen as representative times to illustrate changes in QTc prolongation between sleeping and waking hours. The median QTc values at these times are identified in Figure 2, and prolongation percentage for the full 24 hours is shown in Figure 3. N is reported as the number of patients with Holter recordings containing data during the required hours.

Percentage of cardiac beats with QTc prolongation	LQT1		LQT2		LQT3
Percentage of cardiac beats with QTc prolongation	Men	Women	Men	Women	Men	Women
N	82	108	40	47	8	5
Period : 3AM–4AM	48%	30%	100%	100%	100%	81%
Period : 3PM–4PM	97%	68%	87%	62%	100%	95%
p-value	0.0002	0.00001	0.0002	0.002	0.2	1.0