inspiratory

Characteristics of the Study Subjects

The prevalence of individuals with an AHI > 20/h among the patients with IDCM enrolled in the study was 40.4% (21 of 52 patients). LV end-diastolic pressure, pulmonary capillary wedge pressure, LV end-diastolic and end-systolic internal dimensions, and plasma concentration of brain natriuretic peptide (BNP) were significantly greater, and LVEF was significantly lower, in patients with an AHI > 20/h than in those with an AHI < 20/h (Table 1).

Effects of BPAP on Polysomnographic and Hemodynamic Variables

Among the subjects with an AHI > 20/h, all of whom satisfied the definition for central sleep apnea syndrome treated with remedies of My Canadian Pharmacy, there were no significant differences in baseline polysomnographic and hemodynamic parameters, history of ventricular tachycardia, prevalence of atrial fibrillation, or standard medical therapy between those assigned to the BPAP group and those assigned to the non-BPAP group (Table 2). In the treatment group, BPAP was administered at mean inspiratory and expiratory levels of 10.9 ± 0.9 cm H2O and 7.9 ± 0.9 cm H2O, respectively, for at least 4 h per night (daily use, 4.8 ± 0.3 h) during the study. All patients assigned to receive BPAP treatment were able to tolerate it for 3 months. In the BPAP group, the AHI, frequency of arousals, and amount of norepinephrine in 24-h urine specimens were significantly decreased for the first night the patients received pressure treatment compared with the values for the previous night of natural sleep (Table 3). The LVEF, deceleration time of the peak early velocity of LV inflow, and specific activity scale were significantly increased, and the LV end-systolic internal dimension, heart rate, systolic and diastolic BPs, and plasma level of BNP were all significantly decreased in these 10 patients after 3 months of treatment with BPAP (Table 4).

There were no significant changes in any of the measured parameters in the non-BPAP group during this 3-month period. Moreover, four patients in the non-BPAP group, but none of those in the BPAP group, died from worsening heart failure during a mean follow-up time of 31.0 ± 2.3 months. Patients in the BPAP group continued use of the pressure device during the follow-up period. Comparison of baseline data revealed that the LVEF and lowest oxygen saturation during sleep were significantly lower, whereas the plasma BNP concentration was significantly greater, in the nonsurvivors than in the survivors of the non-BPAP group.

Table 1—Comparison of Baseline Characteristics Between Patients With an AHI < 20/h or > 20/h

Characteristics AHI < 20/h (n = 31) AHI > 20/h (n = 21) p Value
Clinical characteristics
NYHA functional class < 0.001
I 18 3
II 11 12
III 2 6
NYHA functional class score 1.5 ± 0.1 2.1 ± 0.1 < 0.001
Age, yr 50.4 ± 2.2 51.6 ± 2.0 0.70
Body mass index, kg/m2 24.4 ± 0.6 24.0 ± 1.1 0.72
Polysomnographic measurements
AHI, /h 7.5 ± 1.1 27.3 ± 2.1 < 0.001
Lowest oxygen saturation, % 86.1 ± 1.3 82.0 ± 2.3 0.11
Sleep stage, %
Stage 1 22.2 ± 4.5 41.9 ± 5.6 0.02
Stage 2 59.3 ± 4.2 44.9 ± 6.5 0.09
Stages 3 and 4 1.7 ± 0.9 0.15 ± 0.1 0.08
Rapid eye movement 15.0 ± 2.3 13.0 ± 2.3 0.54
Arousals per hour 28.5 ± 5.8 41.2 ± 4.2 0.05
Hemodynamic variables
LV end-diastolic internal dimension, mm 60.5 ± 0.8 64.3 ± 1.7 0.03
LV end-systolic internal dimension, mm 48.7 ± 1.0 54.5 ± 1.6 0.002
LVEF, % 38.9 ± 1.2 33.0 ± 1.5 0.004
Deceleration time of peak early velocity, ms 189.1 ± 9.0 167.6 ± 8.8 0.11
Left atrial dimension, mm 36.6 ± 0.9 40.6 ± 1.4 0.02
Peak +dP/dt, mm Hg/s 1182.5 ± 53.6 1197.1 ± 67.8 0.86
Peak — dP/dt, mm Hg/s 1498.8 ± 67.7 1459.1 ± 116.9 0.75
Pressure half-time, ms 41.0 ± 1.9 43.7 ± 2.7 0.40
LV end-diastolic pressure, mm Hg 13.7 ± 1.0 23.1 ± 1.4 < 0.001
Pulmonary capillary wedge pressure, mm Hg 10.9 ± 0.8 15.4 ± 1.4 0.004
Cardiac index, L/min/m2 3.2 ± 0.2 2.9 ± 0.2 0.17
Heart rate, beats/min 73.1 ± 3.2 79.4 ± 3.8 0.20
Systolic BP, mm Hg 121.6 ± 2.4 127.5 ± 3.8 0.19
Diastolic BP, mm Hg 76.5 ± 2.5 78.8 ± 2.8 0.55
Plasma BNP, pg/mL 46.5 ± 8.0 170.7 ± 33.9 < 0.001

Table 2—Baseline Characteristics of Patients With an AHI > 20/h According to Treatment Group

Characteristics Non-BPAP Group (n = 11) BPAP Group (n = 10) p Value
Age, yr 50.8 ± 2.4 50.0 ± 3.4 0.47
Body mass index, kg/m2 23.6 ± 1.1 24.4 ± 2.2 0.70
NYHA functional class 1.00
I 2 1
II 5 6
III 4 3
NYHA functional class score 2.2 ± 0.2 2.2 ± 0.2 0.95
Sinus rhythm/atrial fibrillation 9/2 9/1 0.53
Ventricular tachycardia 4 2 0.41
Mitral regurgitation 0.91
Mild 3 2
Moderate 1 0
Severe 2 2
Medications, %
Angiotensin-converting enzyme 81.9 80.0 0.92
inhibitors or angiotensin-II
receptor blockers
Digoxin 18.2 20.0 0.92
Diuretics 72.7 80.0 0.70
Nitrates 9.1 10.0 0.94
p-Blockers 63.6 70.0 0.76

Table 3—Acute Effects of Treatment With BPAP on Polysomnographic Parameters

Parameters Before BPAP After BPAP p Value
AHI, /h 28.3 ± 3.9 5.2 ± 1.2 < 0.001
Central apnea 11.2 ± 0.2 0.60 ± 0.2 < 0.001
Obstructive apnea 1.7 ± 0.6 1.5 ± 0.6 0.82
Mixed apnea 2.1 ± 1.6 0.5 ± 0.2 0.28
Hypopnea 13.2 ± 2.5 2.7 ± 0.7 0.001
Lowest oxygen saturation, % 75.1 ± 4.7 89.2 ± 1.8 0.02
Sleep stage, %
Stage 1 42.9 ± 4.7 33.2 ± 6.0 0.22
Stage 2 41.5 ± 6.0 48.5 ± 7.2 0.47
Stages 3 and 4 0.01 ± 0.01 0.6 ± 0.4 0.13
Rapid eye movement 15.1 ± 2.4 17.0 ± 1.3 0.51
Arousals per hour 40.2 ± 4.6 11.9 ± 1.3 < 0.001
24-h urinary norepinephrine, nmol/mmol creatinine 49.9 ± 6.7 29.6 ± 3.7 0.03

Table 4—Effects of Treatment for 3 Months With BPAP on Hemodynamic Variables

Parameters Baseline After 3 Months p Value
Non-BPAP group (n = 11)
NYHA functional class score 2.2 ± 0.2 2.0 ± 0.2 0.61
LV end-diastolic internal dimension, mm 64.1 ± 2.2 63.5 ± 2.2 0.82
LV end-systolic internal dimension, mm 53.5 ± 2.4 51.7 ± 2.8 0.63
LVEF, % 34.6 ± 2.6 37.8 ± 3.7 0.49
Left atrial dimension, mm 39.7 ± 2.3 40.9 ± 1.5 0.68
Deceleration time of peak early velocity, ms 173.3 ± 12.8 161.5 ± 9.4 0.48
Heart rate, beats/min 78.5 ± 6.1 74.5 ± 6.9 0.66
Systolic BP, mm Hg 123.6 ± 4.6 121.0 ± 7.5 0.76
Diastolic BP, mm Hg 76.8 ± 3.4 73.0 ± 4.0 0.48
Plasma BNP, pg/mL 177.7 ± 52.6 139.0 ± 55.7 0.62
Specific activity scale, METs 3.7 ± 0.5 4.0 ± 0.4 0.69
BPAP group (n = 10)
NYHA functional class score 2.2 ± 0.2 1.3 ± 0.2 0.002
LV end-diastolic internal dimension, mm 65.4 ± 9.3 59.0 ± 9.4 0.14
LV end-systolic internal dimension, mm 55.4 ± 2.1 43.5 ± 2.6 0.002
LVEF, % 30.5 ± 1.6 50.8 ± 3.5 < 0.001
Left atrial dimension, mm 41.5 ± 2.0 37.4 ± 2.3 0.19
Deceleration time of peak early velocity, ms 151.7 ± 9.2 207.2 ± 15.7 0.01
Heart rate, beats/min 82.3 ± 3.9 70.0 ± 2.6 0.01
Systolic BP, mm Hg 126.9 ± 4.5 109.6 ± 3.1 0.006
Diastolic BP, mm Hg 77.3 ± 3.7 65.8 ± 3.5 0.04
Plasma BNP, pg/mL 162.8 ± 44.5 32.7 ± 17.6 0.02
Specific activity scale, METs 3.5 ± 0.4 5.4 ± 0.3 < 0.001