Left Ventricular Dysfunction and Sleep Apnea Syndrome: Cause or Consequence?

Abstract

To the Editor:In an article published recently in CHEST (October 2002),1Laaban JP Pascal-Sebaoun S Bloch E et al.Left ventricular systolic dysfunction in patients with obstructive sleep apnea syndrome.Chest. 2002; : 1133-1138Abstract Full Text Full Text PDF Scopus (149) Google Scholar Dr. Laaban and colleagues conclude that obstructive sleep apnea syndrome (OSAS) may be a direct cause of daytime left ventricular systolic dysfunction (LVSD) that can resolve following reversal of nocturnal apneas by nasal continuous positive airway pressure (CPAP). We would like to take this opportunity to make some suggestions.First, this finding can not definitely rule out the hypothesis that LVSD and/or congestive heart failure may be the cause of OSAS and not the opposite. Indeed, a high prevalence and persistence of sleep apnea are observed in patients with chronic left ventricular failure.2Tremel F Pepin JL Veale D et al.High prevalence and persistence of sleep apnoea in patients referred for acute left ventricular failure and medically treated over 2 months.Eur Heart J. 1999; 20: 1201-1209Crossref PubMed Scopus (129) Google Scholar3Andreas S Nocturnal insights in chronic heart failure.Eur Heart J. 1999; 20: 1140-1141Crossref PubMed Scopus (8) Google Scholar Rather, as CPAP improves cardiac output in patients with LVSD,4Pinsky MR Summer WR Wise RA et al.Augmentation of cardiac function by elevation of intrathoracic pressure.J Appl Physiol. 1983; 54: 950-955Crossref PubMed Scopus (171) Google Scholar the useful effect of nasal CPAP observed in the study by Yan et al5Yan AT Bradley TD Liu PP The role of continuous positive airway pressure in the treatment of congestive heart failure.Chest. 2001; 120: 1675-1685Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar could be a direct effect of positive pressure ventilation on heart. Thus, we are not sure about the validity of these results and we may expect that after a time of optimal medical treatment (angiotensin-converting enzyme inhibitors [23% patients treated in the study], diuretics, …) the episodes of OSAS may be treated.Second, the authors have stated that associated cardiac disease had been excluded in the present study. We may expect that this statement may be erroneous, as to our knowledge the onset of an idiopathic dilated cardiomyopathy in patients with LVSD could not be excluded. Finally, we believe that more research is required to better understand the pathophysiologic association between OSAS and LVSD and to define the potential role of CPAP in the treatment of chronic heart failure. To the Editor: In an article published recently in CHEST (October 2002),1Laaban JP Pascal-Sebaoun S Bloch E et al.Left ventricular systolic dysfunction in patients with obstructive sleep apnea syndrome.Chest. 2002; : 1133-1138Abstract Full Text Full Text PDF Scopus (149) Google Scholar Dr. Laaban and colleagues conclude that obstructive sleep apnea syndrome (OSAS) may be a direct cause of daytime left ventricular systolic dysfunction (LVSD) that can resolve following reversal of nocturnal apneas by nasal continuous positive airway pressure (CPAP). We would like to take this opportunity to make some suggestions. First, this finding can not definitely rule out the hypothesis that LVSD and/or congestive heart failure may be the cause of OSAS and not the opposite. Indeed, a high prevalence and persistence of sleep apnea are observed in patients with chronic left ventricular failure.2Tremel F Pepin JL Veale D et al.High prevalence and persistence of sleep apnoea in patients referred for acute left ventricular failure and medically treated over 2 months.Eur Heart J. 1999; 20: 1201-1209Crossref PubMed Scopus (129) Google Scholar3Andreas S Nocturnal insights in chronic heart failure.Eur Heart J. 1999; 20: 1140-1141Crossref PubMed Scopus (8) Google Scholar Rather, as CPAP improves cardiac output in patients with LVSD,4Pinsky MR Summer WR Wise RA et al.Augmentation of cardiac function by elevation of intrathoracic pressure.J Appl Physiol. 1983; 54: 950-955Crossref PubMed Scopus (171) Google Scholar the useful effect of nasal CPAP observed in the study by Yan et al5Yan AT Bradley TD Liu PP The role of continuous positive airway pressure in the treatment of congestive heart failure.Chest. 2001; 120: 1675-1685Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar could be a direct effect of positive pressure ventilation on heart. Thus, we are not sure about the validity of these results and we may expect that after a time of optimal medical treatment (angiotensin-converting enzyme inhibitors [23% patients treated in the study], diuretics, …) the episodes of OSAS may be treated. Second, the authors have stated that associated cardiac disease had been excluded in the present study. We may expect that this statement may be erroneous, as to our knowledge the onset of an idiopathic dilated cardiomyopathy in patients with LVSD could not be excluded. Finally, we believe that more research is required to better understand the pathophysiologic association between OSAS and LVSD and to define the potential role of CPAP in the treatment of chronic heart failure. Left Ventricular Dysfunction and Sleep Apnea SyndromeCHESTVol. 123Issue 5PreviewWe thank Dr. Bendjelid for his interest in our study. He suggested that obstructive sleep apnea syndrome (OSAS) was not the cause but the consequence of left ventricular (LV) systolic dysfunction and that LV systolic dysfunction could be due to an idiopathic dilated cardiomyopathy. I agree that a high prevalence of OSAS has been reported in patients with chronic LV failure. Full-Text PDF