Table 2 Sleep study and echocardiography results.

From: Sleep apnea and diabetes mellitus are independently associated with cardiovascular events and hospitalization for heart failure after coronary artery bypass grafting

Characteristics

Sleep apnea (+)

DM (+)

(n = 295)

Sleep apnea (+) DM (─)

(n = 218)

Sleep apnea (─) DM (+)

(n = 278)

Sleep apnea (─)

DM (─)

(n = 216)

p value

Sleep study

AHI, events per hour, median (IQR)

31.3 (22.0–46.1)

27.9 (19.5–43.6)

5.9 (3.2–10.4)

5.75 (2.8–10)

< 0.001

RDI, events per hour, median (IQR)

34.6 (25.2–47.9)

30.7 (23.4–47.0)

9.5 (6.2–13.9)

11.5 (7.5–15.6)

< 0.001

ODI, events per hour, median (IQR)

19.9 (12.1–36.1)

15.7 (10.2–29.8)

2.5 (1.1–5.0)

2.1 (0.7–4.5)

< 0.001

Sleep duration, hour, median (IQR)

6.5 (5.4–7.3)

6.3 (5.6–7.2)

6.3 (5.4–7.0)

6.4 (5.3–7.3)

0.501

Duration SpO2 < 90%, min, median (IQR)

5.8 (0.8–24.6)

3.7 (0.3–14.0)

0.0 (0.0–0.5)

0.0 (0.0–0.6)

< 0.001

Percentage of sleep SpO2 < 90%, %, median (IQR)

1.5 (0.2–6.3)

1.0 (0.1–3.9)

0.0 (0.0–0.1)

0.0 (0.0–0.2)

< 0.001

Epworth Sleepiness Scale, median (IQR)*

5.0 (3.0–8.0)

6.0 (3.0–9.0)

5.0 (2.0–8.0)

4.5 (2.0–7.0)

0.066

High-risk Berlin Questionnaire, n (%)*

139 (47.3)

100 (46.1)

120 (43.3)

81 (37.7)

0.157

Transthoracic echocardiography

Left ventricular ejection fraction, median (IQR), %

48 (35–60)

55 (42.8–60)

55 (45–61)

55 (45–60)

< 0.001

Left ventricular ejection fraction, n (%)

    

< 0.001

 > 50%

112 (41.3)

111 (57.2)

142 (57.5)

122 (65.9)

 

30–50%

105 (38.7)

53 (27.3)

77 (31.2)

43 (23.2)

 

 < 30%

54 (19.9)

30 (15.5)

28 (11.3)

20 (10.8)

 

Left atrium diameter, median (IQR), mm

41 (37–45)

40 (36–44)

38 (35–42)

38 (35–42)

< 0.001

Left ventricular end–diastolic internal diameter, median (IQR), mm

52 (47–56)

52 (48–57)

49 (45–53)

55 (46–55)

< 0.001

Left ventricular end–systolic internal diameter, median (IQR), mm

37 (31–45)

35 (31–42)

33 (28–39.5)

33 (29–39.5)

< 0.001

Left ventricular mass index, median (IQR), g/m2

109 (91–132.5)

104.5 (87.8–132.5)

99 (81.3–120.8)

96.5 (83–127)

< 0.001

Aortic root diameter, median (IQR), mm

33 (30–35)

33 (31–36)

32 (30–35)

33 (31–35)

0.003

E/A, median (IQR)

0.9 (0.7–1.4)

0.8 (0.7–1.3)

0.8 (0.7–1.2)

0.9 (0.7–1.3)

0.564

Pulmonary artery systolic pressure, median (IQR), mmHg

32 (25.6–43)

28.3 (23.5–35.2)

28 (24–34)

29 (24–35)

0.005

  1. Four patients did not undergo the questionnaires.
  2. AHI apnea–hypopnea index, BQ Berlin Questionnaire, DM diabetes mellitus, ESS Epworth Sleepiness Scale, IQR interquartile range, ODI oxygen desaturation index, RDI respiratory disturbance index, SD standard deviation, SpO2 arterial oxygen saturation.
  3. AHI = the number of apnea or hypopnea events per hour of sleep.
  4. RDI = the number of apnea, hypopnea, or respiratory effort related arousals per hour of sleep.
  5. ODI = the number of times per hour of sleep that the blood oxygen level drop by at least 4% from baseline.
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