Suppression of central sleep apnea by continuous positive airway pressure and transplant-free survival in heart failure: a post hoc analysis of the Canadian Continuous Positive Airway Pressure for Patients with Central Sleep Apnea and Heart Failure Trial (CANPAP).
BACKGROUND
In the main analysis of the Canadian Continuous Positive Airway Pressure (CPAP) for Patients with Central Sleep Apnea (CSA) and Heart Failure Trial (CANPAP), CPAP had no effect on heart transplant-free survival; however, CPAP only reduced the mean apnea-hypopnea index to 19 events per hour of sleep, which remained above the trial inclusion threshold of 15. This stratified analysis of CANPAP tested the hypothesis that suppression of CSA below this threshold by CPAP would improve left ventricular ejection fraction and heart transplant-free survival.


RESULTS
Of the 258 heart failure patients with CSA in CANPAP, 110 of the 130 randomized to the control group and 100 of the 128 randomized to CPAP had sleep studies 3 months later. CPAP patients were divided post hoc into those whose apnea-hypopnea index was or was not reduced below 15 at this time (CPAP-CSA suppressed, n=57, and CPAP-CSA unsuppressed, n=43, respectively). Their changes in left ventricular ejection fraction and heart transplant-free survival were compared with those in the control group. Despite similar CPAP pressure and hours of use in the 2 groups, CPAP-CSA-suppressed subjects experienced a greater increase in left ventricular ejection fraction at 3 months (P=0.001) and significantly better transplant-free survival (hazard ratio [95% confidence interval] 0.371 [0.142 to 0.967], P=0.043) than control subjects, whereas the CPAP-CSA-unsuppressed group did not (for left ventricular ejection fraction, P=0.984, and for transplant-free survival, hazard ratio 1.463 [95% confidence interval 0.751 to 2.850], P=0.260).


CONCLUSIONS
These results suggest that in heart failure patients, CPAP might improve both left ventricular ejection fraction and heart transplant-free survival if CSA is suppressed soon after its initiation.
Arzt
Michael
M
University of Toronto, Toronto, Ontario, Canada.
Floras
John S
JS
Logan
Alexander G
AG
Kimoff
R John
RJ
Series
Frederic
F
Morrison
Debra
D
Ferguson
Kathleen
K
Belenkie
Israel
I
Pfeifer
Michael
M
Fleetham
John
J
Hanly
Patrick
P
Smilovitch
Mark
M
Ryan
Clodagh
C
Tomlinson
George
G
Bradley
T Douglas
TD
D000368:Aged; D002317:Cardiovascular Agents / Q000627:therapeutic use; D002639:Cheyne-Stokes Respiration / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D003131:Combined Modality Therapy; D045422:Continuous Positive Airway Pressure; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000188:drug therapy / Q000401:mortality / Q000601:surgery; D016027:Heart Transplantation; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D017286:Polysomnography; D016016:Proportional Hazards Models; D012720:Severity of Illness Index; D016037:Single-Blind Method; D020182:Sleep Apnea, Central / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D013318:Stroke Volume; D016019:Survival Analysis; D013564:Sympathetic Nervous System / Q000503:physiopathology; D016896:Treatment Outcome
D002317:Cardiovascular Agents; D010100:Oxygen