title: Evidence that the degree of obstructive sleep apnea may not increase myocardial ischemia and arrhythmias in patients with stable coronary artery disease.
abstract: There is controversy regarding whether obstructive sleep apnea is responsible for triggering myocardial ischemia, arrhythmias and heart rate variability in patients with coronary artery disease.
  
  
  OBJECTIVE
  The objective of this study was to identify relationships between sleep apnea, myocardial ischemia and cardiac arrhythmia in patients with coronary artery disease.
  
  
  METHODS
  Fifty-three patients with stable coronary disease underwent simultaneous polysomnography and electrocardiographic Holter recording. The apnea-hypopnea index (AHI) was defined as the number of apneas/hypopneas per hour of sleep. Patients were divided into a Control group (AHI15, n=23 pts) and an Apnea group (AHI>15, n=30 pts). A subgroup of 13 patients with an AHI>30 (Severe Apnea group) was also studied. We analyzed ischemic episodes (ST-segment depressions >1 mm, > 1 min), heart rate variability and the occurrence of arrhythmias during wakefulness and sleep.
  
  
  RESULTS
  Baseline clinical characteristics among the groups were similar except for higher blood pressure in the Apnea groups (p<0.05). Myocardial ischemia was recorded in 39 (73.6%) patients. The number and duration of ischemic episodes significantly decreased during sleep in all groups; during wakefulness, patients with severe apnea exhibited fewer and shorter episodes in comparison with the controls. There were no significant differences in heart rate variability or in the occurrence of arrhythmias among the groups. Malignant ventricular arrhythmias, atrial fibrillation/flutter, bradycardia and high-degree atrioventricular blocks were not detected.
  
  
  CONCLUSIONS
  Obstructive sleep apnea was not related to myocardial ischemia, heart rate variability or arrhythmias in patients with stable coronary artery disease and did not alter the circadian pattern of myocardial ischemia.
authors.affiliation: Departament of Clinical Cardiology, Instituto do Coração do Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo - São Paulo/SP, Brazil.
authors.forename: Cristiana Marques de
authors.initials: CM
authors.lastname: Araújo
authors.forename: Maria Cecilia
authors.initials: MC
authors.lastname: Solimene
authors.forename: Cesar Jose
authors.initials: CJ
authors.lastname: Grupi
authors.forename: Pedro Rodrigues
authors.initials: PR
authors.lastname: Genta
authors.forename: Geraldo
authors.initials: G
authors.lastname: Lorenzi-Filho
authors.forename: Protásio Lemos
authors.initials: PL
authors.lastname: Da Luz