title: Exercise capacity and paroxysmal atrial fibrillation in patients with hypertrophic cardiomyopathy.
abstract: BACKGROUND
  Atrial fibrillation (AF) is the most common arrhythmia among patients with hypertrophic cardiomyopathy (HCM). The relationship between paroxysmal AF and exercise capacity in this population is incompletely understood.
  
  
  METHODS
  Patients with HCM underwent symptom-limited cardiopulmonary testing with expired gas analysis at Stanford Hospital between October 2006 and October 2012. Baseline demographics, medical histories and resting echocardiograms were obtained for all subjects. Diagnosis of AF was established by review of medical records and baseline ECG. Those with paroxysmal AF were in sinus rhythm at the time of cardiopulmonary testing with expired gas analysis. Exercise intolerance was defined as peak VO2<20 mL/kg/min. We used multivariate logistic regression to evaluate the association between exercise intolerance and paroxysmal AF.
  
  
  RESULTS
  Among the 265 patients recruited, 55 had AF (28 paroxysmal and 27 permanent). Compared with those without AF, subjects with paroxysmal AF were older, more likely to use antiarrhythmic and anticoagulant medications, and had larger left atria. Patients with paroxysmal AF achieved lower peak VO2 (21.9±9.2 mL/kg/min vs 26.9±10.8 mL/kg/min, p=0.02) and were more likely to have exercise intolerance (61% vs 28%, p<0.001) compared with those without AF. After adjustment for age, sex and body mass index (BMI) exercise intolerance remained significantly associated with paroxysmal AF (OR 4.65, 95% CI 1.83 to 11.83, p=0.001).
  
  
  CONCLUSIONS
  Patients with HCM and paroxysmal AF demonstrate exercise intolerance despite being in sinus rhythm at the time of exercise testing.
authors: Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, , Stanford, California, USA.
authors: Farnaz
authors: F
authors: Azarbal
authors: Maneesh
authors: M
authors: Singh
authors: Gherardo
authors: G
authors: Finocchiaro
authors: Vy-Van
authors: VV
authors: Le
authors: Ingela
authors: I
authors: Schnittger
authors: Paul
authors: P
authors: Wang
authors: Jonathan
authors: J
authors: Myers
authors: Euan
authors: E
authors: Ashley
authors: Marco
authors: M
authors: Perez
mesh_terms: D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D000925:Anticoagulants / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology; D001944:Breath Tests; D002140:California; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D016009:Chi-Square Distribution; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors
chemical_list: D000889:Anti-Arrhythmia Agents; D000925:Anticoagulants
keywords: Hypertrophic cardiomyopathy; atrial fibrillation; exercise capacity