title: Abnormal heart rate recovery and deficient chronotropic response after submaximal exercise in young Marfan syndrome patients.
abstract: BACKGROUND
  Marfan syndrome patients present important cardiac structural changes, ventricular dysfunction, and electrocardiographic changes. An abnormal heart rate response during or after exercise is an independent predictor of mortality and autonomic dysfunction. The aim of the present study was to compare heart rate recovery and chronotropic response obtained by cardiac reserve in patients with Marfan syndrome subjected to submaximal exercise.
  
  
  METHODS
  A total of 12 patients on β-blocker therapy and 13 off β-blocker therapy were compared with 12 healthy controls. They were subjected to submaximal exercise with lactate measurements. The heart rate recovery was obtained in the first minute of recovery and corrected for cardiac reserve and peak lactate concentration.
  
  
  RESULTS
  Peak heart rate (141±16 versus 155±17 versus 174±8 bpm; p=0.001), heart rate reserve (58.7±9.4 versus 67.6±14.3 versus 82.6±4.8 bpm; p=0.001), heart rate recovery (22±6 versus 22±8 versus 34±9 bpm; p=0.001), and heart rate recovery/lactate (3±1 versus 3±1 versus 5±1 bpm/mmol/L; p=0.003) were different between Marfan groups and controls, respectively. All the patients with Marfan syndrome had heart rate recovery values below the mean observed in the control group. The absolute values of heart rate recovery were strongly correlated with the heart rate reserve (r=0.76; p=0.001).
  
  
  CONCLUSIONS
  Marfan syndrome patients have reduced heart rate recovery and chronotropic deficit after submaximal exercise, and the chronotropic deficit is a strong determinant of heart rate recovery. These changes are suggestive of autonomic dysfunction.
authors.affiliation: 1Department of Cardiology,Federal University of São Paulo,São Paulo,Brasil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Peres
authors.affiliation: 1Department of Cardiology,Federal University of São Paulo,São Paulo,Brasil.
authors.forename: Antônio C
authors.identifier: http://orcid.org/0000-0001-7453-6738
authors.initials: AC
authors.lastname: Carvalho
authors.affiliation: 3Medical Genetics Center,Federal University of São Paulo,São Paulo,Brasil.
authors.forename: Ana Beatriz A
authors.initials: AB
authors.lastname: Perez
authors.affiliation: 1Department of Cardiology,Federal University of São Paulo,São Paulo,Brasil.
authors.forename: Wladimir M
authors.identifier: http://orcid.org/0000-0002-7199-6170
authors.initials: WM
authors.lastname: Medeiros
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001938:Brazil; D016022:Case-Control Studies; D002648:Child; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008382:Marfan Syndrome / Q000188:drug therapy / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D000319:Adrenergic beta-Antagonists
keywords: Marfan syndrome; autonomic function; heart rate; mortality; physical exercise