title: Association of Fragmented QRS with Subclinical Left Ventricular Dysfunction in Patients with Obstructive Sleep Apnea.
abstract: OBJECTIVE
  We aimed to investigate whether fragmented QRS (fQRS) is associated with subclinical left ventricular (LV) dysfunction in patients with obstructive sleep apnea (OSA).
  
  
  METHODS
  A total of 141 patients with OSA who had normal LV ejection fraction (LVEF) were included in the study. The fQRS was defined as the presence of an additional R wave, notching of R or S wave or the presence of fragmentation in 2 contiguous electrocardiography (ECG) leads. Subclinical LV dysfunction was defined as the presence of a tissue Doppler-derived Tei index of ≥ 0.5 in the absence of impaired LVEF (<50%) as assessed by transthoracic echocardiography.
  
  
  RESULTS
  Of the 141 patients, 71 (50.4%) had subclinical LV dysfunction. Overall, the prevalence of the fQRS was 61% (86/141). Patients with fQRS had significantly higher Tei indices than those without fQRS [median 0.66, interquartile range (IQR) 0.39 vs. median 0.40, IQR 0.15, p < 0.001]. The presence of fQRS on ECG predicted subclinical LV dysfunction in univariate logistic regression analysis [odds ratio (OR) 6.69, 95% confidence interval (CI) 3.10-14.43]. The association remained significant after adjusting for all potential confounders (OR 4.59, 95% CI 1.94-10.87).
  
  
  CONCLUSIONS
  fQRS on ECG was an independent predictor of subclinical LV dysfunction in patients with OSA. This simple tool might help to identify OSA patients who could be at risk for developing overt cardiac dysfunction.
authors.affiliation: Department of Cardiology, Faculty of Medicine, Karabuk University Hospital, Karabuk University, Karabuk, Turkey.
authors.forename: Adem
authors.initials: A
authors.lastname: Adar
authors.forename: Abdulkadir
authors.initials: A
authors.lastname: Kırış
authors.forename: Yılmaz
authors.initials: Y
authors.lastname: Bülbül
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Bektaş
authors.forename: Murat
authors.initials: M
authors.lastname: Acat
authors.forename: Hasan
authors.initials: H
authors.lastname: Casim
authors.forename: Orhan
authors.initials: O
authors.lastname: Onalan
mesh_terms: D000328:Adult; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011859:Radiography; D018570:Risk Assessment; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology*; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000453:epidemiology*