Cardiol Res

Cardiology Research, ISSN 1923-2829 print, 1923-2837 online, Open Access

Article copyright, the authors; Journal compilation copyright, Cardiol Res and Elmer Press Inc

Journal website https://cr.elmerpub.com

Original Article

Volume 17, Number 3, June 2026, pages 181-189

Strong Adherence to Cardiac Rehabilitation Program Improves Exercise Tolerance in Outpatients With Cardiovascular Disease

↓ Figure 2. The changes in RER, VO₂/wt, and VO₂/HR in a cardiopulmonary exercise test from the initial test to a second test in patients who participated in CR less than once a week (a) and in those who participated in CR once a week or more (b) are shown. The blue line indicates the results at the initial test and the orange line indicates the results at the second test. *Indicates a significant difference between the initial and second tests. RER: respiratory exchange ratio; VO₂/wt: oxygen uptake per body weight; VO₂/HR: oxygen uptake per heart rate; AT: anaerobic threshold.

↓ Figure 3. The changes in VE, TV, and RR in the cardiopulmonary exercise test from the initial test to the second test in patients who participated in CR less than once a week (a) and those who participated in CR once a week or more (b) are shown. The blue line indicates the results at the initial test and the orange line indicates the results at the second test. *Indicates a significant difference between the initial and second tests. VE: ventilation equivalent; TV: tidal volume; RR: respiratory rate; AT: anaerobic threshold.

↓ Figure 4. The changes in VE/VO₂ and VE/VCO₂ in the cardiopulmonary exercise test from the initial test to the second test in patients who participated in CR less than once a week (a) and those who participated in CR once a week or more (b) are shown. The blue line indicates the results at the initial test and the orange line indicates the results at the second test. *Indicates a significant difference between the initial and second tests. VE/VO₂: ventilation equivalent per oxygen uptake; VE/VCO₂; ventilation equivalent per carbon dioxide output; AT: anaerobic threshold.

↓ Figure 5. The changes in VE/VCO₂ slope, minimum VE/VCO₂, OUES, and ΔVO₂/ΔWR in the cardiopulmonary exercise test from the initial test to the second test in patients who participated in CR less than once a week (a) and those who participated in CR once a week or more (b) are shown. *Indicates a significant difference between the initial and second tests. VE/VCO₂: ventilation equivalent per carbon dioxide output; OUES: oxygen-uptake efficiency slope; ΔVO₂/ΔWR: the ratio of the increase in oxygen uptake to the increase in work rate; AT: anaerobic threshold.

↓ **Table 1.** Patient Characteristics in All Patients and the Groups That Visited CR Less Than Once a Week Group and Once a Week More Group
Variables	All cases	CR less than once a week	CR once a week more	P value
Underlying CVD represents the indication to CR. P value showed the comparison between CR less than once a week group and CR once a week more group. *Operation indicates cardiac valvular operation. CR: cardiac rehabilitation; Missing: number of missing value; BMI: body mass index; HT: hypertension; DM: diabetes mellitus; DLP: dyslipidemia; CKD: chronic kidney disease; COPD: chronic obstructive pulmonary disease; CVD: cardiovascular disease; IHD: ischemic heart disease; HF: heart failure; MVD: macrovascular disease; RAAS: renin-angiotensin-aldosterone system; CCB: calcium channel blocker; BB: beta-blocker; MRA: mineral corticoid antagonist; PCI: percutaneous coronary intervention; CABG: coronary artery bypass graft; ICD: implantable cardioverter defibrillator; CRT: cardiac resynchronization therapy; TC: total cholesterol; TG: triglyceride; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; BNP: brain natriuretic peptide; LVEF: left ventricular ejection fraction; TRPG: tricuspid regurgitation pressure gradient.
Frequency of CR, /week		1.54 (0.93-1.89)		0.79 (0.53–0.92)		1.77 (1.53–2.20)	< 0.001
Duration of CR, days		106 ± 29		108 ± 35		105 ± 26	0.52
Age, years		68.5 (59–74)		67 (51–74)		69 (64–74)	0.28
Male, n (%)		76 (69.1)		24 (68.6)		52 (69.3)	0.94
BMI, kg/m²		23.8 ± 3.6		24.0 ± 3.8		23.7 ± 3.6	0.68
Smoking, n (%)		59 (57.8)		23 (67.6)		36 (52.9)	0.16
Underlying disease
HT, n (%)	1	74 (67.9)	1	24 (70.6)		50 (66.7)	0.68
DM, n (%)	1	34 (31.2)	1	11 (32.4)		23 (30.7)	0.86
DLP, n (%)	1	73 (67.0)	1	23 (67.6)		50 (66.7)	0.92
CKD, n (%)	1	52 (47.7)	1	16 (47.1)		36 (48.0)	0.93
COPD, n (%)	1	1 (0.9)	1	0 (0)		1 (1.3)	0.50
Underlying CVD
IHD, n (%)		57 (51.8)		21 (60.0)		36 (48.0)	0.24
HF, n (%)	1	51 (46.8)		20 (58.8)	1	31 (41.3)	0.09
MVD, n (%)	1	9 (8.3)		1 (2.9)	1	8 (10.7)	0.17
Medication
RAAS, n (%)	21	63 (70.8)	6	22 (75.9)	15	41 (68.3)	0.46
CCB, n (%)	21	39 (43.8)	6	10 (34.5)	15	29 (48.3)	0.22
Diuretics, n (%)	21	33 (37.1)	6	16 (55.2)	15	17 (28.3)	0.01
BB, n (%)	21	58 (65.2)	6	23 (79.3)	15	35 (58.3)	0.18
MRA, n (%)	21	26 (29.2)	6	12 (41.4)	15	14 (23.3)	0.08
Statin, n (%)	12	62 (63.3)	3	20 (62.5)	9	42 (63.6)	0.91
PCI, n (%)	1	41 (37.6)		16 (47.1)	1	25 (33.3)	0.17
CABG, n (%)	1	10 (9.2)		1 (2.9)	1	9 (12.0)	0.13
Operation*, n (%)	1	20 (18.3)		8 (23.5)	1	12 (16.0)	0.35
ICD/CRT, n (%)	1	6 (5.5)		1 (2.9)	1	5 (6.7)	0.43
Examinations
TC, mg/dL	14	169 (153–201)	3	171 (152–192)	11	168 (156–206)	0.66
TG, mg/dL	17	121 (96–174)	3	117 (78–177)	14	133 (97–174)	0.59
LDL-C, mg/dL	18	98.2 ± 34.7	4	95.0 ± 32.8	14	99.8 ± 35.8	0.54
HDL-C, mg/dL	18	49.1 ± 14.2	4	48.3 ± 9.6	14	49.5 ± 16.1	0.65
BNP, pg/mL		81.7 (27.6–225)		84.4 (29.4–254)		80.9 (27.6–214)	0.88
LVEF, %	25	59.0 (44.6–67.9)	7	54.9 (40.1–65.5)	18	62.4 (45.3–68.5)	0.18
E/e'	48	11.5 (8.6–15.2)	16	13.0 (10.1–21.5)	32	10.3 (7.5–14.8)	0.07
TRPG, mm Hg	49	20.5 ± 7.5	17	19.3 ± 7.9	32	20.9 ± 7.4	0.07

↓ Table 1. Patient Characteristics in All Patients and the Groups That Visited CR Less Than Once a Week Group and Once a Week More Group

Variables

All cases

CR less than once a week

CR once a week more

P value

Missing

n = 110

Missing

n = 35

Missing

n = 75

Underlying CVD represents the indication to CR. P value showed the comparison between CR less than once a week group and CR once a week more group. *Operation indicates cardiac valvular operation. CR: cardiac rehabilitation; Missing: number of missing value; BMI: body mass index; HT: hypertension; DM: diabetes mellitus; DLP: dyslipidemia; CKD: chronic kidney disease; COPD: chronic obstructive pulmonary disease; CVD: cardiovascular disease; IHD: ischemic heart disease; HF: heart failure; MVD: macrovascular disease; RAAS: renin-angiotensin-aldosterone system; CCB: calcium channel blocker; BB: beta-blocker; MRA: mineral corticoid antagonist; PCI: percutaneous coronary intervention; CABG: coronary artery bypass graft; ICD: implantable cardioverter defibrillator; CRT: cardiac resynchronization therapy; TC: total cholesterol; TG: triglyceride; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; BNP: brain natriuretic peptide; LVEF: left ventricular ejection fraction; TRPG: tricuspid regurgitation pressure gradient.

Frequency of CR, /week

1.54 (0.93-1.89)

0.79 (0.53–0.92)

1.77 (1.53–2.20)

< 0.001

Duration of CR, days

106 ± 29

108 ± 35

105 ± 26

0.52

Age, years

68.5 (59–74)

67 (51–74)

69 (64–74)

0.28

Male, n (%)

76 (69.1)

24 (68.6)

52 (69.3)

0.94

BMI, kg/m²

23.8 ± 3.6

24.0 ± 3.8

23.7 ± 3.6

0.68

Smoking, n (%)

59 (57.8)

23 (67.6)

36 (52.9)

0.16

Underlying disease

HT, n (%)

74 (67.9)

24 (70.6)

50 (66.7)

0.68

DM, n (%)

34 (31.2)

11 (32.4)

23 (30.7)

0.86

DLP, n (%)

73 (67.0)

23 (67.6)

50 (66.7)

0.92

CKD, n (%)

52 (47.7)

16 (47.1)

36 (48.0)

0.93

COPD, n (%)

1 (0.9)

0 (0)

1 (1.3)

0.50

Underlying CVD

IHD, n (%)

57 (51.8)

21 (60.0)

36 (48.0)

0.24

HF, n (%)

51 (46.8)

20 (58.8)

31 (41.3)

0.09

MVD, n (%)

9 (8.3)

1 (2.9)

8 (10.7)

0.17

Medication

RAAS, n (%)

63 (70.8)

22 (75.9)

41 (68.3)

0.46

CCB, n (%)

39 (43.8)

10 (34.5)

29 (48.3)

0.22

Diuretics, n (%)

33 (37.1)

16 (55.2)

17 (28.3)

0.01

BB, n (%)

58 (65.2)

23 (79.3)

35 (58.3)

0.18

MRA, n (%)

26 (29.2)

12 (41.4)

14 (23.3)

0.08

Statin, n (%)

62 (63.3)

20 (62.5)

42 (63.6)

0.91

PCI, n (%)

41 (37.6)

16 (47.1)

25 (33.3)

0.17

CABG, n (%)

10 (9.2)

1 (2.9)

9 (12.0)

0.13

Operation*, n (%)

20 (18.3)

8 (23.5)

12 (16.0)

0.35

ICD/CRT, n (%)

6 (5.5)

1 (2.9)

5 (6.7)

0.43

Examinations

TC, mg/dL

169 (153–201)

171 (152–192)

168 (156–206)

0.66

TG, mg/dL

121 (96–174)

117 (78–177)

133 (97–174)

0.59

LDL-C, mg/dL

98.2 ± 34.7

95.0 ± 32.8

99.8 ± 35.8

0.54

HDL-C, mg/dL

49.1 ± 14.2

48.3 ± 9.6

49.5 ± 16.1

0.65

BNP, pg/mL

81.7 (27.6–225)

84.4 (29.4–254)

80.9 (27.6–214)

0.88

LVEF, %

59.0 (44.6–67.9)

54.9 (40.1–65.5)

62.4 (45.3–68.5)

0.18

E/e'

11.5 (8.6–15.2)

13.0 (10.1–21.5)

10.3 (7.5–14.8)

0.07

TRPG, mm Hg

20.5 ± 7.5

19.3 ± 7.9

20.9 ± 7.4

0.07

↓ **Table 2.** Major Differences in CPX From First to Second Test in Patients Who Participated in CR Once a Week or More Compared to Whom in CR Less Than Once a Week
	All cases (n = 110)	CR less than once a week (n = 35)	CR once a week more (n = 75)	P value
CPX: cardiopulmonary exercise test; CR: cardiac rehabilitation; VO₂/wt: oxygen uptake per body weight; VO₂/HR: oxygen uptake per heart rate; AT: anaerobic threshold; VE: ventilation equivalent.
VO₂/wt at 1-min before AT, mL/kg/min	1.30 (−0.30 to 2.20)	0.80 (−1.00 to 2.10)	1.50 (−0.10 to 2.60)	0.013
VO₂/wt at AT, mL/kg/min	2.00 (0.40–4.00)	1.40 (−0.10 to 3.30)	2.30 (0.40–4.20)	0.035
VO₂/HR at 1-min before AT, mL/beat/min	1.07 (0–1.76)	0.57 (−0.47 to 1.42)	1.23 (0.34–1.88)	0.007
VO₂/HR at AT, mL/beat/min	0.92 (0.22–2.01)	0.50 (−0.47 to 1.67)	1.07 (0.34–2.26)	0.030
VE at 1-min before AT, L/min	0.40 (−0.70 to 3.10)	0 (−1.40 to 1.40)	0.90 (−0.50 to 3.50)	0.018
VE at AT, L/min	3.24 (0.05–7.19)	2.14 (−2.67 to 5.87)	4.84 (0.95–8.35)	0.066

↓ Table 2. Major Differences in CPX From First to Second Test in Patients Who Participated in CR Once a Week or More Compared to Whom in CR Less Than Once a Week

All cases (n = 110)

CR less than once a week (n = 35)

CR once a week more (n = 75)

P value

CPX: cardiopulmonary exercise test; CR: cardiac rehabilitation; VO₂/wt: oxygen uptake per body weight; VO₂/HR: oxygen uptake per heart rate; AT: anaerobic threshold; VE: ventilation equivalent.

VO₂/wt at 1-min before AT, mL/kg/min

1.30 (−0.30 to 2.20)

0.80 (−1.00 to 2.10)

1.50 (−0.10 to 2.60)

0.013

VO₂/wt at AT, mL/kg/min

2.00 (0.40–4.00)

1.40 (−0.10 to 3.30)

2.30 (0.40–4.20)

0.035

VO₂/HR at 1-min before AT, mL/beat/min

1.07 (0–1.76)

0.57 (−0.47 to 1.42)

1.23 (0.34–1.88)

0.007

VO₂/HR at AT, mL/beat/min

0.92 (0.22–2.01)

0.50 (−0.47 to 1.67)

1.07 (0.34–2.26)

0.030

VE at 1-min before AT, L/min

0.40 (−0.70 to 3.10)

0 (−1.40 to 1.40)

0.90 (−0.50 to 3.50)

0.018

VE at AT, L/min

3.24 (0.05–7.19)

2.14 (−2.67 to 5.87)

4.84 (0.95–8.35)

0.066