Published Online
on June 11, 2007

A more recent version of this article appeared on June 26, 2007

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Submitted on December 11, 2006
Accepted on April 9, 2007

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)

Michael Arzt MD, John S. Floras MD, DPhil, Alexander G. Logan MD, R. John Kimoff MD, Frederic Series MD, Debra Morrison MD, Kathleen Ferguson MD, Israel Belenkie MD, Michael Pfeifer MD, John Fleetham MD, Patrick Hanly MD, Mark Smilovitch MD, Clodagh Ryan MD, George Tomlinson PhD, T. Douglas Bradley MD^*, for the CANPAP Investigators

From the University of Toronto (M.A., J.S.F., A.G.L., P.H., C.R., G.T., T.D.B.), Toronto, Ontario, Canada; University of British Columbia (J.F.), Vancouver, British Columbia, Canada; University of Calgary (I.B., P.H.), Calgary, Alberta, Canada; University of Western Ontario (K.F.), London, Ontario, Canada; McGill University (R.J.K., M.S.), Montreal, Quebec, Canada; Laval University (F.S.), Quebec City, Quebec, Canada; Dalhousie University (D.M.), Halifax, Nova Scotia, Canada; and the University of Regensburg (M.P.), Regensburg, Germany.

^* To whom correspondence should be addressed. E-mail: douglas.bradley{at}utoronto.ca.

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.

Methods and 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.

Key words: apnea, sleep • heart failure • respiration • sleep • survival • trials

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