The Effect of Successful Heart Transplant Treatment of Heart Failure on Central Sleep Apnea: Results

Between the years of 1999 and 2000, 37 patients with severe CHF underwent heart transplantation workup that included full polysomnography who subsequently received a heart transplant: 16 patients had CSA, 6 patients had OSA, and 15 patients had no SDB (control group). In the CSA group following heart transplantation, one patient was excluded due to allograft dysfunction, one patient due to failure to achieve clinical stability, and one patient refused repeat polysomnography. The 13 remaining patients agreed to follow-up polysomnography and were included in the analysis, of whom 10 patients underwent orthotopic transplantation, and 3 patients underwent heterotopic transplantation. In the control group, two patients failed to achieve clinical stability and four patients refused repeat polysomnography, leaving nine patients to act as a matched control group, each of whom had an orthotopic transplant. None of the patients studied had any clinical evidence of neurologic impairment following transplantation.
The pretransplant baseline characteristics for both CSA and control groups are shown in Table 1. The two groups had similar degrees of CHF, as indicated by similar LVEF and New York Heart Association (NYHA) class plus type of cardiomyopathy; however, the CSA group tended to be older. Here

Following heart transplantation, both groups had significant improvements in LVEF and NYHA classification, associated with significant reductions in UNE (Table 2). Sleep efficiency and sleep stage distribution were not significantly different at baseline between the CSA and control groups, nor did they change in either group following transplantation (Table 3). The arousal index was greater at baseline and tended to fall after transplantation in the CSA group, compared with the control group in which there was no change. Arterial blood gas estimates were unchanged following transplantation. Overnight oxygenation improved in the CSA group following transplantation.
Table 1—Patient Characteristics

Characteristics Control Group (n = 9) CSA Group (n = 13) p Value
Age, yr 44 ± 10 54 ± 9 0.02
Male/female gender, No. 5/4 13/0
Pretransplant time, mof 10.1 ± 9.9 9.9 ± 8.9 NS
Posttransplant time, mo{ 20.6 ± 10.7 13.2 ± 8.3 0.08
Body mass index 25.5 ± 3.5 26.2 ± 3.7 NS
Pretransplant LVEF, % 26.4 ± 11.4 19.2 ± 9.3 0.12
NYHA class 3.0 ± 1.2 3.0 ± 0.8 NS
Ischemic/idiopathic, No. 3/6 5/8
AHI, events/h 2 ± 1 28 ± 15 < 0.01

Table 2—Patient Characteristics Before and After Heart Transplant

Characteristics Control Group p Value CSA Group p Value
Before After Before After
Body mass index 25.5 ± 3.5 26.5 ± 3.5 NS 26.2 ± 3.7 26.6 ± 3.0 NS
LVEF, % 26.4 ± 11.4 54.6 ± 6.8 < 0.001 19.2 ± 9.3 53.7 ± 6.1 < 0.001
NYHA class 3.0 ± 1.2 1.9 ± 0.3 0.03 3.0 ± 0.8 2.1 ± 0.3 0.05
Pao2, mm Hg 89 ± 12 90 ± 8 NS 89 ± 10 86 ± 15 NS
Paco2, mm Hg 40 ± 3 43 ± 3 NS 38 ± 5 39 ± 3 NS
pH 7.44 ± 0.03 7.41 ± 0.02 NS 7.46 ± 0.03 7.43 ± 0.03 NS

Table 3—Polysomnography and Catecholamine Data Before and After Heart Transplantation

Control Group CSA Group
Variables Before After p Value Before After p Value
Time in bed, min 416 ± 30 439 ± 29 NS 396 ± 64 414 ± 40 NS
Total sleep time, min 321 ± 72 332 ± 77 NS 280 ± 78 277 ± 65 NS
SPT, min 401 ± 36 412 ± 37 NS 377 ± 62 376 ± 47 NS
Sleep efficiency, % 77 ± 15 76 ± 17 NS 69 ± 15 67 ± 12 NS
Wake, % SPT 21 ± 14 20 ± 15 NS 26 ± 16 27 ± 9 NS
Stages 1 and 2, % SPT 57 ± 12 58 ± 8 NS 58 ± 11 56 ± 6 NS
Slow-wave sleep, % SPT 10 ± 6 7 ± 6 NS 5 ± 7 5 ± 6 NS
Rapid eye movement, % SPT 12 ± 3 14 ± 7 NS 11 ± 7 13 ± 10 NS
Arousals, No./h 27 ± 38 20 ± 22 NS 43 ± 36 72 ± 62 NS
Heart rate, beats/min 71 ± 14 78 ± 7 NS 69 ± 10 80 ± 15 0.01
AHI, No./h 2 ± 2 1 ± 1 NS 28 ± 15 7±6 < 0.01
CSA, % total sleep time 63 ± 32 11 ± 1t 0.02
CSA cycle length, s 65 ± 14 31 ± 7t < 0.01
CSA ventilation: apnea length ratio 2.6 ± 0.9 0.7 ± 0.3t < 0.01
Mean Spo2, % 95.2 ± 2.9 96.4 ± 1.2 NS 94.7 ± 1.8 96.3 ± 1.6 < 0.01
Minimum Spo2, % 91.7 ± 4.6 92.0 ± 2.9 NS 85.5 ± 3.9 90.7 ± 5.2 < 0.01
Time Spo2 < 90%, % total sleep time 6.6 ± 12.5 0.1 ± 0.3 NS 5.2 ± 10.8 1.4 ± 4.9 0.06
UNE, nmol/mmol creatinine 21.1 ± 15.5 6.2 ± 4.0 0.2 48.1 ± 30.9 6.5 ± 4.8 < 0.01
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