Author + information
- Received November 7, 1996
- Revision received April 28, 1997
- Accepted May 16, 1997
- Published online July 1, 1997.
- Ruzena Tkacova, MD, PhDA,
- Peter P Liu, MD, FACCB,
- Matthew T Naughton, MDA and
- T.Douglas Bradley, MDA,*
- ↵*T. Douglas Bradley, 212-10 EN The Toronto Hospital (TGD), 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada.
Objectives. We sought to determine the effects of continuous positive airway pressure (CPAP) on mitral regurgitant fraction (MRF) and plasma atrial natriuretic peptide (ANP) concentration in patients with congestive heart failure (CHF).
Background. In patients with CHF, elevated plasma ANP concentration is associated with elevated cardiac filling pressures. Secondary mitral regurgitation may contribute to elevation in plasma ANP concentration in patients with CHF. Because CPAP reduces transmural cardiac pressures and left ventricular (LV) volume, we hypothesized that long-term CPAP application would decrease the MRF and plasma ANP concentration in patients with CHF and Cheyne-Stokes respiration with central sleep apnea (CSR-CSA).
Methods. Seventeen patients with CHF and CSR-CSA underwent baseline assessments of plasma ANP concentration and left ventricular ejection fraction (LVEF) and MRF by radionuclide angiography. They were then randomized to receive nocturnal CPAP plus optimal medical therapy (n = 9) or optimal medical therapy alone (n = 8) for 3 months and were then reassessed.
Results. In the CPAP-treated group, LVEF increased from (mean ± SEM) 20.2 ± 4.2% to 28.2 ± 5.3% (p < 0.02); MRF decreased from 32.8 ± 7.7% to 19.4 ± 5.5% (p < 0.02); and plasma ANP concentration decreased from 140.9 ± 20.8 to 103.9 ± 17.0 pg/ml (p < 0.05). The control group experienced no significant changes in LVEF, MRF or plasma ANP concentration. Among all patients, the change in plasma ANP concentration from baseline to 3 months correlated significantly with the change in MRF (r = 0.789, p < 0.0002).
Conclusions. In patients with CHF, CPAP-induced reductions in MRF and plasma ANP concentration in association with improvements in LVEF indicate improved cardiac mechanics. Our findings also suggest that reductions in plasma ANP concentration were at least partly due to reductions in MRF.
☆ This study was supported by Operating Grant MA-12422 from the Medical Research Council of Canada, Ottawa, and the Ontario Ministry of Health, Toronto; and by a research fellowship from Respironics Incorporation, Murrysville, Pennsylvania (Dr. Tkacova). Dr. Liu is a Career Investigator of the Heart and Stroke Foundation of Ontario, Toronto, and Dr. Bradley is a Career Scientist of the Ontario Ministry of Health.
- Received November 7, 1996.
- Revision received April 28, 1997.
- Accepted May 16, 1997.