Table 1 Demographic and clinical characteristics of the study population

Female sex no. [%]

14 (73.7)

16 (84.2)

30 (78.9)

Age [years]

54.89 ± 11.23

(49.48 to 60.31)

58.79 ± 10.75

(53.61 to 63.97)

(− 3.33 to 11.12)

56.84 ± 11.02

(53.22 to 60.46)

Height [cm]

166.21 ± 10.19

(161.30 to 171.12)

166.05 ± 5.59

(163.36 to 168.75)

(− 5.62 to 5.31)

166.13 ± 8.11

(163.47 to 168.80)

Weight [kg]

74.81 ± 17.25

(66.48 to 83.10)

71.45 ± 15.83

(64.03 to 79.22)

(− 14.03 to 7.70)

73.13 ± 16.42

(67.83 to 78.59)

Systolic blood pressure [mmHg]

121.32 ± 14.99

(114.09 to 128.54)

116.32 ± 11.53

(110.76 to 121.87)

(− 13.80 to 3.80)

118.82 ± 13.43

(114.40 to 123.23)

Diastolic blood pressure [mmHg]

73.42 ± 9.14

(69.02 to 77.82)

73.68 ± 8.95

(69.37 to 78.00)

(− 5.69 to 6.21)

73.55 ± 8.92

(70.62 to 76.49)

HR [beats/min]

77.58 ± 9.85

(72.83 to 82.33)

73.05 ± 11.12

(67.69 to 78.41)

(− 11.44 to 2.39)

75.32 ± 10.61

(72.83 to 78.81)

 II

15 (78.9)

17 (89.5)

32 (84.2)

 III

4 (21.1)

2 (10.5)

6 (15.8)

 mPAP rest 21–24 mmHg, mPAP exercise > 30 mmHg

12 (63.2)

10 (52.6)

22 (57.9)

 mPAP rest 21–24 mmHg, mPAP exercise ≤ 30 mmHg

3 (15.8)

1 (5.3)

4 (10.5)

 mPAP rest < 21 mmHg, mPAP exercise > 30 mmHg

4 (21.0)

8 (42.1)

2 (31.6)

 mRSS [points]

11.47 ± 5.22

(8.72 to 14.23)

11.47 ± 5.71

(8.96 to 13.99)

(− 3.60 to 3.60)

11.47 ± 5.40

(9.70 to 13.25)

 Diffuse

11 (57.9)

4 (21.1)

15 (39.5)

 Limited

8 (42.1)

15 (78.9)

23 (60.5)

 SSc disease duration [years]

13.28 ± 10.85

(8.05 to 18.51)

6.63 ± 4.80

(4.32 to 8.96)

(− 12.17 to 1.12)

9.96 ± 8.93

(7.02 to 12.90)

 CVP [mmHg]

5.63 ± 2.97

(4.20 to 7.06)

6.11 ± 2.94

(4.69 to 7.52)

(− 1.47 to 2.41)

5.87 ± 2.92

(4.90 to 6.82)

 mPAP [mmHg]

21.32 ± 2.43

(20.15 to22.49)

19.84 ± 3.58

(18.12 to 21.57)

(− 3.49 to 0.54)

20.58 ± 3.11

(19.56 to 21.60)

 PAWP [mmHg]

9.58 ± 2.97

(8.15 to 11.01)

9.42 ± 2.32

(8.30 to 10.54)

(− 1.91 to 1.59)

9.50 ± 2.63

(8.64 to 10.37)

 CO [l/min]

5.66 ± 1.48

(4.95 to 6.37)

5.04 ± 1.26

(4.43 to 5.65)

(− 1.51 to 0.29)

5.35 ± 1.39

(4.89 to 5.81)

 CI [l/min/m²]

3.20 ± 0.85

(2.79 to 3.61)

2.84 ± 0.64

(2.53 to 3.14)

(− 0.86 to 0.13)

3.02 ± 0.76

(2.77 to 3.27)

 SvO₂ [%]

73.13 ± 4.60

(70.67 to 75.58)

(16)

73.91 ± 8.58

(69.50 to 78.32)

(17)

(− 4.15 to 5.71)

73.53 ± 6.85

(71.10 to 75.96)

(33)

 PVR [WU]

2.09 ± 0.61

(1.80 to 2.39)

2.22 ± 0.93

(1.77 to 2.67)

(− 0.39 to 0.65)

2.16 ± 0.78

(1.90 to 2.41)

 mPAP [mmHg]

36.94 ± 6.08

(33.82 to 40.07)

(17)

37.78 ± 3.61

(35.98 to 39.57)

(18)

(− 2.58 to 2.25)

37.37 ± 4.91

(35.69 to 39.06)

(35)

 PAWP [mmHg]

15.24 ± 5.43

(12.45 to 18.03)

(17)

16.78 ± 6.42

(13.58 to 19.97)

(18)

(− 2.56 to 5.64)

16.03 ± 5.92

(13.99 to 18.06)

(35)

 CO [l/min]

11.03 ± 3.62

(9.17 to 12.89)

(17)

9.67 ± 2.67

(8.34 to 10.99)

(18)

(− 3.54 to 0.81)

10.33 ± 3.19

(9.23 to 11.43)

(35)

 CI [l/min/m²]

6.04 ± 1.79

(5.12 to 6.96)

(17)

5.41 ± 1.32

(4.75 to 6.06)

(18)

(− 1.71 to 0.45)

5.71 ± 1.58

(5.17 to 6.25)

(35)

 SvO₂ [%]

38.27 ± 6.10

(34.89 to 41.64)

(15)

42.77 ± 11.56

(36.36 to 49.17)

(15)

(− 2.42 to 11.42)

40.52 ± 9.37

(37.02 to 44.02)

(30)

 Workload [Watt]

75.00 ± 34.23

(57.40 to 92.60)

(17)

75.00 ± 27.12

(61.52 to 88.48)

(18)

(− 21.18 to 21.17)

75.00 ± 30.32

(65.59 to 85.41)

(35)

 HR max [/min]

117.65 ± 21.37

(106.66 to 128.63)

(17)

111.39 ± 23.06

(99.92 to 122.86)

(18)

(− 21.57 to 9.06)

114.43 ± 22.15

(106.82 to 122.04)

(35)

 PVR [WU]

2.07 ± 0.61

(1.76 to 2.38)

(17)

2.29 ± 0.85

(1.87 to 2.71)

(18)

(− 0.29 to 0.73)

2.18 ± 0.74

(1.93 to 2.44)

(35)

 TPR [mmHg min l^− 1]

3.65 ± 1.18

(3.04 to 4.26)

(17)

4.28 ± 1.65

(3.46 to 5.10)

(18)

(− 0.36 to 1.62)

3.97 ± 1.46

(3.47 to 4.47)

(35)

 6MWD [m]

448.11 ± 82.64

(408.28 to 487.93)

470.21 ± 77.03

(433.08 to 407.34)

(− 30.46 to 74.67)

459.16 ± 79.59

(433.00 to 485.32)

 Borg dyspnea score

2.93 ± 1.97

(1.98 to 3.88)

2.41 ± 1.32

(1.77 to 3.04)

(− 1.63 to 0.58)

2.67 ± 1.68

(2.11 to 3.22)

 SaO₂ after 6MWD [%]

91.87 ± 4.63

(89.30 to 94.43)

(15)

91.71 ± 4.79

(89.24 to 94.17)

(17)

(− 3.57 to 3.25)

91.78 ± 4.64

(90.10 to 93.45)

(32)

 HR after 6MWD [/min]

99 ± 21.27

(88.07 to 109.93)

(17)

107 ± 19.64

(96.90 to 117.10)

(17)

(− 6.30 to 22.30)

103 ± 20.56

(95.82 to 110.17)

(34)

 Estimated sPAP [mmHg]

29.21 ± 5.16

(25.25 to 31.17)

28.58 ± 6.57

(26.04 to 31.43)

(− 4.52 to 3.26)

28.89 ± 5.83

(26.98 to 30.81)

 RA area [cm²]

12.05 ± 4.24

(10.73 to 13.69)

11.68 ± 3.28

(10.45 to 13.66)

(− 2.86 to 2.13)

11.87 ± 3.74

(10.64 to 13.10)

 RV area [cm²]

14.89 ± 4.56

(12.97 to 17.03)

14.13 ± 4.74

(12.65 to 16.82)

(− 3.82 to 2.30)

14.51 ± 4.60

(13.00–16.03)

 TAPSE [cm]

2.50 ± 0.51

(2.23 to 2.71)

2.41 ± 0.33

(2.28 to 2.70)

(− 0.37 to 0.20)

16,834 ± 0.43

(2.31 to 2.60)

 FVC [%]

69.17 ± 13.72

(62.56 to 75.78)

70.51 ± 17.61

(62.02 to 79.00)

(− 6.37 to 1.84)

69.84 ± 15.58

(64.72 to 74.96)

 FEV1 [L]

2.40 ± 0.77

(2.03 to 2.77)

2.26 ± 0.63

(1.96 to 2.57)

(− 0.60 to 0.33)

2.33 ± 0.70

(2.10 to 2.56)

 FEV1% VC max [%]

79.31 ± 6.98

(75.95 to 82.68)

81.44 ± 15.38

(74.03 to 88.85)

(− 5.73 to 9.99)

80.38 ± 11.83

(76.49 to 84.27)

 PEF [l/s]

5.46 ± 2.32

(4.34 to 6.58)

5.17 ± 1.72

(4.34 to 6.00)

(− 1.63 to 1.06)

5.31 ± 2.02

(4.65 to 5.98)

 TLC [l]

4.96 ± 1.07

(4.44 to 5.48)

5.08 ± 1.25

(4.48 to 5.69)

(− 0.64 to 0.89)

5.02 ± 1.15

(4.64 to 5.40)

 Residual volume [l]

1.94 ± 0.55

(1.68 to 2.21)

2.18 ± 0.70

(1.84 to 2.52)

(− 0.18 to 0.65)

2.06 ± 0.63

(1.85 to 2.27)

 DLCO [mmol/min/kPa]

5.28 ± 1.52

(4.55 to 6.02)

5.03 ± 1.33

(4.38 to 5.67)

(− 1.20 to 0.68)

5.16 ± 1.42

(4.69 to 5.62)

 DLCO % predicted

84.73 ± 2.61

(83.47 to 85.99)

84.16 ± 1.89

(83.25 to 85.08)

(− 2.07 to 0.93)

84.45 ± 2.27

(83.70 to 85.19)

 SaO₂ [%]

96.13 ± 1.80

(95.26 to 97.00)

96.82 ± 0.77

(96.45 to 97.17)

(− 0.23 to 1.60)

96.47 ± 1.41

(96.01 to 96.94)

 PaO₂ [mmHg]

78.78 ± 9.42

(74.24 to 83.32)

81.22 ± 5.91

(78.37 to 84.06)

(− 2.74 to 7.61)

80.00 ± 7.85

(77.42 to 82.58)

 PaCO₂ [mmHg]

39.01 ± 3.63

(37.25 to 40.76)

37.23 ± 2.57

(35.99 to 38.47)

(− 3.85 to 0.29)

38.12 ± 3.23

(37.05 to 39.18)

 Hemoglobin [g/dl]

13.54 ± 1.26

(12.93 to 14.14)

13.62 ± 1.13

(13.07 to 14.16)

(− 0.71 to 0.87)

13.58 ± 1.18

(13.19 to 13.96)

 Hematocrit [l/l]

0.42 ± 0.03

(0.40 to 0.43)

0.41 ± 0.03

(0.40 to 0.43)

(− 0.03 to 0.02)

0.41 ± 0.03

(0.40 to 0.42)

 Platelet [100/nl]

2.53 ± 0.94

(2.08 to 2.98)

2.62 ± 0.63

(2.31 to 2.92)

(− 0.44 to 0.61)

2.58 ± 0.79

(2.32 to 2.83)

 Creatinine [mg/dl]

0.83 ± 0.16

(0.75 to 0.91)

0.86 ± 0.12

(0.80 to 0.92)

(− 0.07 to 0.13)

0.85 ± 0.14

(0.80 to 0.89)

 Potassium [mmol/l]

4.05 ± 0.38

(3.86 to 4.23)

4.20 ± 0.48

(3.97 to 4.43)

(− 0.13 to 0.44)

4.12 ± 0.43

(3.98 to 4.27)

 AST [U/l]

24.11 ± 21.78

(13.61 to 34.60)

19.79 ± 7.06

(16.39 to 23.19)

(− 14.97 to 6.34)

21.95 ± 16.12

(16.65 to 27.25)

 ALT [U/l]

29.68 ± 24.93

(17.67 to 41.70)

24.68 ± 9.85

(19.93 to 29.43)

(− 17.47 to 7.47)

27.18 ± 18.87

(20.98 to 33.39)

 LDH [U/l]

197.63 ± 54.74

(171.25 to 224.01)

197.53 ± 35.59

(180.37 to 214.68)

(− 30.48 to 30.27)

197.58 ± 45.54

(182.61 to 212.55)

 CRP [mg/l]

5.18 ± 5.17

(2.69 to 7.68)

5.28 ± 11.60

(− 0.48 to 11.05)

(18)

(− 5.84 to 6.04)

5.23 ± 8.77

(2.30 to 8.16)

(37)

 NTproBNP [pg/ml]

123.42 ± 142.96

(54.52 to 192.32)

267.83 ± 303.11

(117.10 to 418.57)

(18)

(− 12.38 to 301.20)

193.68 ± 242.81

(112.71 to 274.63)

(37)

 Physical functioning

50.26 ± 25.95

(37.75 to 62.77)

64.21 ± 25.83

(51.67 to 76.66)

(− 3.09 to 30.99)

57.24 ± 26.50

(48.52 to 65.95)

 Physical role functioning

35.53 ± 40.24

(16.13 to 54.92)

51.32 ± 41.23

(31.45 to 79.19)

(− 11.01 to 42.59)

43.42 ± 40.97

(29.96 to 56.89)

 Bodily pain

49.79 ± 28.96

(35.83 to 63.75)

62.00 ± 29.16

(47.95 to 76.05)

(− 6.91 to 31.33)

55.89 ± 29.33

(46.26 to 65.53)

 General health perceptions

41.74 ± 13.07

(35.44 to 48.04)

54.42 ± 19.47

(45.03 to 63.81)

(1.72 to 23.65)

48.08 ± 17.58

(42.30 to 53.86)

 Vitality

42.89 ± 19.32

(33.58 to 52.20)

50.53 ± 20.94

(40.03 to 60.62)

(− 5.62 to 20.89)

46.71 ± 20.24

(40.06 to 53.37)

 Social role functioning

58.05 ± 25.99

(45.53 to 70.58)

74.47 ± 24.45

(62.69 to 86.26)

(− 0.18 to 33.03)

66.26 ± 26.24

(57.64 to 74.89)

 Emotional role functioning

49.16 ± 46.33

(26.83 to 71.49)

63.16 ± 47.02

(40.50 to 85.82)

(− 16.71 to 44.71)

56.16 ± 46.58

(40.85 to 71.47)

 Mental health

59.58 ± 18.85

(50.49 to 68.66)

64.42 ± 18.03

(55.73 to 73.11)

(− 7.30 to 16.98)

62.00 ± 18.36

(55.97 to 68.04)

 Physical health score

43.89 ± 21.26

(33.65 to 54.14)

56.47 ± 23.87

(44.97 to 67.98)

(− 2.29 to 27.45)

50.18 ± 23.19

(42.56 to 57.81)

 Mental health score

50.26 ± 20.70

(40.29 to 60.24)

61.42 ± 21.45

(51.08 to 71.76)

(− 2.71 to 25.03)

55.84 ± 21.55

(48.76 to 62.92)