title: The relationship between heart rate recovery and brain natruretic Peptide in patients with chest discomfort: a study for relationship between heart rate recovery and pre-exercise, post-exercise levels of brain natruretic Peptide in patients with normal systolic function and chest discomfort.
abstract: OBJECTIVE
  The correlation between brain natruretic peptide (BNP) level and cardiac autonomic function has been studied in type 2 diabetic patients. However, there is limited data from patients with normal systolic function. We evaluated the association between heart rate recovery (HRR) representing autonomic dysfunction and three plasma BNP levels: pre-exercise, post-exercise, and change during exercise in patients with normal systolic function.
  
  
  METHODS
  Subjects included 105 patients with chest pain and normal systolic function. HRR was defined as the difference between the peak heart rate and the rate measured two minutes after completion of a treadmill exercise test. We measured plasma BNP levels before exercise, 5 minutes after completion of exercise, and during exercise (absolute value of difference between pre- and post-exercise BNP levels).
  
  
  RESULTS
  Patients with abnormal HRR values (</=24 beats for the first 2 minutes of HRR) had lower high-density lipoprotein, lower peak heart rates, and higher pre- and post-exercise BNP levels than patients with normal HRR values. The patients with coronary artery disease (CAD) had abnormal HRR. However, no significant differences were found between the two groups in terms of history of hypertension (HTN), diabetes, and peak systolic blood pressure (SBP) and diastolic blood pressure (DBP). HRR was significantly associated with pre-exercise BNP (r=-0.36, p=0.004) and post-exercise BNP (r=-0.27, p=0.006), but not BNP changes. Further, pre-exercise BNP levels showed a greater association with HRR than post-exercise BNP levels.
  
  
  CONCLUSIONS
  HRR is independently associated with pre-exercise and post-exercise BNP levels, even in patients with normal systolic function.
authors.affiliation: Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jae Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Bum Soo
authors.initials: BS
authors.lastname: Kim
authors.forename: Wan
authors.initials: W
authors.lastname: Park
authors.forename: Jung Kwon
authors.initials: JK
authors.lastname: Huh
authors.forename: Byung Jin
authors.initials: BJ
authors.lastname: Kim
authors.forename: Ki Chul
authors.initials: KC
authors.lastname: Sung
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Kang
authors.forename: Man Ho
authors.initials: MH
authors.lastname: Lee
authors.forename: Jung Ro
authors.initials: JR
authors.lastname: Park