Table 2.

Clinical Characteristics and Electrocardiographic Findings According to DIFF Tertiles (N = 102)

	DIFF, bpm			P
	T1 (−3.1–12.3), n = 34	T2 (13.1–22.2), n = 34	T3 (22.3–42.4), n = 34
Age, y	74 ± 8	74 ± 8	71 ± 7	0.976
Male, n (%)	19 (55.9)	24 (75.0)	24 (75.0)	0.094
Body mass index, kg/m2	23.6 ± 4.0	24.5 ± 2.7	23.9 ± 3.1	0.722
Creatinine, mg/dL	0.853 ± 0.249	0.899 ± 0.211	0.816 ± 0.140	0.622
SBP, mm Hg	130.7 ± 18.2	136.9 ± 19.6	132.0 ± 10.2	0.645
DBP, mm Hg	73.9 ± 11.3	79.5 ± 9.6	73.6 ± 11.2	0.209
Medication, n (%)
Digitalis	15 (44.1)	14 (41.2)	17 (50.0)	0.565
CCBs	7 (20.6)	8 (23.5)	7 (20.6)	0.772
β‐Blockers	15 (44.1)	13 (38.2)	10 (29.4)	0.440
ACEI/ARBs	14 (41.2)	16 (47.1)	17 (50.0)	0.559
Diuretics	9 (26.5)	9 (26.5)	5 (14.7)	0.480
BNP, pg/mL	247.1 ± 159.1	131.8 ± 76.6	114.0 ± 70.4	<0.001
Ambulatory electrocardiogram
Max HR, bpm	127.1 ± 26.8	139.8 ± 24.5	159.0 ± 23.9	0.004
Mean HR, bpm	74.4 ± 12.4	74.6 ± 12.9	80.0 ± 12.4	0.175
Min HR, bpm	44.5 ± 12.6	42.0 ± 12.9	38.8 ± 11.8	0.268
SDRR	200.3 ± 53.3	230.4 ± 68.2	238.8 ± 62.1	0.006
SDARR	97.4 ± 47.3	132.0 ± 51.0	162.3 ± 56.6	0.002
RMSSD	92.1 ± 14.6	92.4 ± 20.9	86.9 ± 16.8	0.955
pRR50	67.8 ± 10.4	65.9 ± 15.5	61.5 ± 12.0	0.680

Abbreviations: ACEIs, angiotensin‐converting enzyme inhibitors; ARBs, angiotensin receptor blockers; BNP, B‐type natriuretic peptide; CCBs, calcium channel blockers; DBP, diastolic blood pressure; DIFF, difference of mean R‐R interval between night and day; Max HR, maximum heart rate; Mean HR, mean heart rate; Min HR, minimum heart rate; pRR50, proportion of adjacent R‐R intervals varying by >50 ms; RMSSD, root‐mean‐square difference of successive R‐R intervals; SBP, systolic blood pressure; SDARR, standard deviation of the mean of all R‐R intervals for all 5‐minute segments; SDRR, standard deviation of all R‐R intervals; T, tertile.

Values are expressed as numbers with percentages in parentheses or as the mean ± standard deviation.