Influence of aging and chronic heart failure on temporal dispersion of myocardial repolarization

Figures & data

Table 1 General characteristics of study sample

Characteristics	Chronic heart failure	Healthy controls	P values
	N = 75	N = 53
Age, years	64 ± 13	60 ± 15	0.452
Male/female	63/12	41/12	0.275
BMI, kg/m^2	26 ± 4	26 ± 3	0.155
HR, beats/min	66 ± 11	68 ± 10	0.329
Systolic blood pressure, mmHg	123 ± 26	122 ± 17	0.700
Diastolic blood pressure, mmHg	66 ± 15	75 ± 11	0.002
Left ventricular ejection fraction, %	40 ± 10	57 ± 4	0.0001
QT, ms	375 ± 58	353 ± 26	0.007
QTBazett, ms	389 ± 51	372 ± 20	0.017
QTFridericia, ms	384 ± 51	366 ± 19	0.008
QTLilly, ms	386 ± 51	361 ± 19	0.011
QTFramingham, ms	385 ± 51	368 ± 18	0.012
NYHA class, I/II/III	10/46/19	0	0.0001
Serum K^+ mmEq/L	4.2	4.1	0.842
β-blockers	35	0	0.0001
Furosemide	33	0	0.0001
ACEi/Sartans	56	5	0.0001
Spironolactone	22	0	0.0001
Digoxin	13	0	0.0001
Amiodarone	11	0	0.017

Note: Data are expressed as means ± standard deviation.

Abbreviations: BMI, body mass index; HR, heart rate; NYHA, New York Heart Association; ACEi, angiotensin converting enzyme; ms, milliseconds; mmEq/L milliequivalents per liter.

Table 2 Mean age of subjects in the three age-subgroups

Age subgroups	Chronic heart failure	Healthy controls	P values
	N = 75	N = 53
≤50 years	46 ± 4 (n = 19)	44 ± 3 (n = 17)	0.371
>50 ≤ 65 years	58 ± 3 (n = 21)	57 ± 4 (n = 18)	0.342
≥65 years	75 ± 6 (n = 35)	77 ± 4 (n = 18)	0.317

Note: Data are expressed as means ± standard deviation.

Table 3 RR interval and QT dynamics data according to age and presence of chronic heart failure

Variables	Group 1 (≤50 years)		P	Group 2 (>50 ≤ 65 years)		P	Group 3 (≥65 years)		P
	CHF (N = 19)	Controls (N = 17)		CHF (N = 21)	Controls (N = 18)		CHF (N = 35)	Controls (N = 18)
RR mean, ms	899 ± 154	945 ± 142	0.354	918 ± 140	906 ± 127	0.785	966 (164)	873 (126)	0.040
RR variance, ms^2	574 (1124)	1627 (2244)^Table Footnote*,Table Footnote#	0.0001	805 ± 1309	885 ± 990^§	0.349	611 (820)	580 (1340)	0.992
QT mean, ms	363 ± 42	359 ± 30	0.801	371 ± 57	355 ± 31	0.294	385 ± 66	347 ± 18	0.008
QT variance, ms^2	36 (84)	18 (14)	0.066	43 (76)	19 (10)	0.011	38 (67)	14 (52)	0.004
Te mean, ms	85 ± 29	86 ± 13^#	0.847	81 ± 18	87 ± 22^†	0.402	91 ± 43	70 ± 13	0.019
Te variance, ms^2	23 (80)	20 (16)^#	0.397	38 (85)	17 (33)^†	0.349	33 (80)	39 (35)	0.696

Notes: Data are expressed as median and interquartile range (75th–25th).

* P < 0.05 Group 1 vs Group 2;

# P < 0.05 Group 1 vs Group 3;

† P < 0.05 Group 2 vs Group 3;

§ P < 0.001 Group 2 vs Group 3.

Abbreviations: CHF, chronic heart failure; TeVI, T_peak-T_end variability index; RR mean or variance, waves interval; ms, milliseconds; QT interval mean or variance.

Table 4 QT variability indices according to age and presence of chronic heart failure

Variables	Group 1 (≤50 years)		P	Group 2 (>50 ≤ 65 years)		P	Group 3 (≥65 years)		P
	CHF (N = 19)	Controls (N = 17)		CHF (N = 21)	Controls (N = 18)		CHF (N = 35)	Controls (N = 18)
QTVI	−0.40 (1.00)	−1.22 (0.35)^Table Footnote*,Table Footnote#	0.0001	−0.54 (0.88)	−1.09 (0.28)^†	0.001	−0.38 (0.90)	−0.77 (0.62)	0.033
TeVI	0.96 (1.00)	0.20 (0.66)^¥	0.003	0.72 (1.02)	0.47 (0.69)^§	0.133	0.77 (1.38)	1.12 (0.72)	0.551
QT/RR STV60	0.49 (0.58)	0.17 (0.63)^#	0.002	0. 38 (0.75)	0.27 (0.46)	0.438	0.53 (0.70)	0.37 (0.51)	0.393
Te/RR STV60	0.54 (1.28)	0.26 (0.28)^#	0.030	0.31 (0.65)	0.33 (0.52)	0.982	0.48 (0.81)	0.58 (0.79)	0.794
QT/RR STVT	0.59 (0.38)	0.18 (0.20)^¥	0.001	0.40 (0.33)	0.31 (0.21)^†	0.256	0.44 (0.62)	0.47 (0.71)	0.460
Te/RR STVT	0.53 (1.09)	0.25 (0.26)^¥	0.022	0.37 (0.36)	0.33 (0.34)^†	0.707	0.46 (0.76)	0.81 (1.11)	0.223

Notes: Data are expressed as median and interquartile range (75th–25th).

* P < 0.05 Group 1 vs Group 2;

# P < 0.05 Group 1 vs Group 3;

¥ P < 0.001 Group 1 vs Group 3;

† P < 0.05 Group 2 vs Group 3;

§ P < 0.001 Group 2 vs Group 3.

Abbreviations: QTVI, QT variability index; TeVI, T_peak-T_end variability index; STV, short term variability.

Figure 1 Relationship between QT variability index (QTVI) or T_peak-T_end variability index (TeVI) and age in healthy control subjects.

Abbreviation: QT, from the Q wave to the T wave end.

Figure 2 Relationship between age and ratio of short-term QT or T_peak-T_end (Te) variability (STV) and resting rate (RR) variability indices, calculated on 60 consecutive beats (QT/RR STV₆₀, Te/RRv STV₆₀) or on 5-minute electrocardiogram recordings (QT/RR STV_T, Te/RRv STV_T) in healthy control subjects.

Abbreviations: QT, from the Q wave to the T wave end; v, variance.

Figure 3 Relationship between age and the resting rate (RR) variability indices (ratio denominator of QTVI, TeVi, and short-term variability [STV], see Methods section), calculated on 5-minute electrocardiogram recordings (RR_variance/RR_mean² and RR STV_T) or on 60 consecutive QRSs (RR STV₆₀) in healthy control subjects.

Abbreviations: TeVI, Tend Variability index; Q-T, waves interval.

Figure 4 Relationship between age and Te variance/Te mean² (ratio numerator of T_peak-T_end variability index, see Methods section).

Notes: No significant relation was reported between age and QT_variance/QT_mean² (ratio numerator of TeVI, see Methods section) in healthy control subjects. Abbreviations: TeVI, Tend Variability index; Q-T, waves interval.