title: Central sleep apnea in left ventricular dysfunction: prevalence and implications for arrhythmic risk.
abstract: BACKGROUND
  The prevalence and characteristics of sleep-disordered breathing in patients with asymptomatic left ventricular (LV) dysfunction are unknown. Therefore, we evaluated the prevalence of sleep-disordered breathing in patients with LV dysfunction without overt heart failure and tested the hypothesis that sleep-disordered breathing is linked to greater hemodynamic and autonomic impairment.
  
  
  RESULTS
  We studied 47 patients with LV ejection fractions <or=40% without any history of heart failure. Central sleep apnea (CSA), as defined by an apnea-hypopnea index >or=15/h, was present in 26 patients (55%), 17 (36%) of whom had severe CSA (apnea-hypopnea index >or=30/h). Obstructive sleep apnea was evident in 5 patients (11%). The prevalence and severity of CSA were higher in patients with ischemic cardiomyopathy than in patients with nonischemic cardiomyopathy (P<0.05). Exercise tolerance and echocardiographic indices of systolic and diastolic function were similar in patients without CSA, with mild CSA, and with severe CSA. Heart rate variability was markedly depressed in patients with CSA (P<0.05). Patients with severe CSA also had a higher incidence of nonsustained ventricular tachycardia (P=0.05).
  
  
  CONCLUSIONS
  CSA is highly prevalent in patients with asymptomatic LV dysfunction. The severity of CSA may not be related to the severity of hemodynamic impairment. Severe CSA is associated with impaired cardiac autonomic control and with increased cardiac arrhythmias.
authors.affiliation: Division of Cardiology, Fondazione Salvatore Maugeri IRCCS, Veruno, Italy. paola-lanfranchi@CRHSC.umontreal.ca
authors.forename: Paola A
authors.initials: PA
authors.lastname: Lanfranchi
authors.forename: Virend K
authors.initials: VK
authors.lastname: Somers
authors.forename: Alberto
authors.initials: A
authors.lastname: Braghiroli
authors.forename: Ugo
authors.initials: U
authors.lastname: Corra
authors.forename: Ermanno
authors.initials: E
authors.lastname: Eleuteri
authors.forename: Pantaleo
authors.initials: P
authors.lastname: Giannuzzi
mesh_terms: D001145:Arrhythmias, Cardiac / Q000209:etiology; D001341:Autonomic Nervous System / Q000503:physiopathology; D002940:Circadian Rhythm; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000294:innervation / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D015995:Prevalence; D011446:Prospective Studies; D012306:Risk; D020182:Sleep Apnea, Central / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology