title: Left atrial size, chemosensitivity, and central sleep apnea in heart failure.
abstract: BACKGROUND
  Central sleep apnea (CSA) is common among patients with heart failure (HF) and is promoted by elevated CO2 chemosensitivity. Left atrial size is a marker of the hemodynamic severity of HF. The aim of this study was to determine if left atrial size predicts chemosensitivity to CO2 and CSA in patients with HF.
  
  
  METHODS
  Patients with HF with left ventricular ejection fraction ≤ 35% underwent polysomnography for detection of CSA, echocardiography, and measurement of CO2 chemosensitivity. CSA was defined as an apnea-hypopnea index (AHI) ≥ 15/h with ≥ 50% central apneic events. The relation of clinical and echocardiographic parameters to chemosensitivity and CSA were evaluated by linear regression, estimation of ORs, and receiver operator characteristics.
  
  
  RESULTS
  Of 46 subjects without OSA who had complete data for analysis, 25 had CSA. The only parameter that significantly correlated with chemosensitivity was left atrial volume index (LAVI) (r = 0.40, P < .01). LAVI was greater in those with CSA than those without CSA (59.2 mL/m2 vs 36.4 mL/m2, P < .001) and significantly correlated with log-transformed AHI (r = 0.46, P = .001). LAVI was the best predictor of CSA (area under the curve = 0.83). A LAVI ≤ 33 mL/m2 was associated with 22% risk for CSA, while LAVI ≥ 53 mL/m2 was associated with 92% risk for CSA.
  
  
  CONCLUSIONS
  Increased LAVI is associated with heightened CO2 chemosensitivity and greater frequency of CSA. LAVI may be useful to guide referral for polysomnography for detection of CSA in patients with HF.
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors: Andrew D
authors: AD
authors: Calvin
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors: Virend K
authors: VK
authors: Somers
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors: Bruce D
authors: BD
authors: Johnson
authors: Department of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN.
authors: Christopher G
authors: CG
authors: Scott
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN. Electronic address: olson.lyle@mayo.edu.
authors: Lyle J
authors: LJ
authors: Olson
mesh_terms: D000368:Aged; D016279:Atrial Function, Left / Q000502:physiology*; D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism*; D004452:Echocardiography / Q000379:methods*; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006333:Heart Failure / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D020182:Sleep Apnea, Central / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D013318:Stroke Volume / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide