title: Cardiac resynchronization therapy improves exercise heart rate recovery in patients with heart failure.
abstract: OBJECTIVE
  Heart rate (HR) recovery (HRR), defined as the rate of decline in the HR immediately following the cessation of exercise, is influenced by autonomic function. Heart rate recovery in heart failure (HF) has been shown to correlate with severity of HF. Cardiac resynchronization therapy (CRT) improves cardiac autonomic functions in HF. We aimed to evaluate the effects of CRT on cardiac autonomic function assessed by HRR.
  
  
  RESULTS
  Forty-eight patients [62.3 ± 10.7 years; 37 men; left ventricular (LV) ejection fraction 24.8 ± 4.1%] with HF were enrolled. A treadmill exercise testing was conducted in all patients by using a modified Naughton protocol before and 6 months after CRT. Heart rate recovery indices were calculated by subtracting first, second, and third minute HR from the maximal HR and designated as HRR1, HRR2, and HRR3, respectively. Standard echocardiography was performed before and 6 months after CRT. Left ventricular reverse remodelling (LVRM) was quantified as the percentage of decline in the LV end-systolic volume after CRT. Mean HRR1 (13.0 ± 5.9 vs. 17.9 ± 8.9 b.p.m., P = 0.001), HRR2 (20.5 ± 9.3 vs. 23.8 ± 11.3 b.p.m., P = 0.001), and HRR3 (25.7 ± 11.1 vs. 29.2 ± 12.0 b.p.m., P = 0.001) values improved 6 months after CRT. Pearson's analyses revealed a good positive correlation between LVRM and ΔHRR1 (r = 0.642, P = 0.001) and a moderate correlation between reduction LVRM and ΔHRR2 (r = 0.591, P = 0.033) and ΔHRR3 (r = 0.436, P = 0.001).
  
  
  CONCLUSIONS
  Cardiac resynchronization therapy favourably alters the cardiac autonomic functions. Heart rate recovery indices improved after CRT and the degree of improvement in HRR indices correlated with LVRM.
authors.affiliation: Department of Cardiology, Hacettepe University Faculty of Medicine, Sihhiye/Ankara, Ankara 06100, Turkey. sercanokutucu@yahoo.com
authors.forename: Sercan
authors.initials: S
authors.lastname: Okutucu
authors.forename: Kudret
authors.initials: K
authors.lastname: Aytemir
authors.forename: Banu
authors.initials: B
authors.lastname: Evranos
authors.forename: Hakan
authors.initials: H
authors.lastname: Aksoy
authors.forename: Cingiz
authors.initials: C
authors.lastname: Sabanov
authors.forename: Ugur Nadir
authors.initials: UN
authors.lastname: Karakulak
authors.forename: Ergun Baris
authors.initials: EB
authors.lastname: Kaya
authors.forename: Giray
authors.initials: G
authors.lastname: Kabakci
authors.forename: Lale
authors.initials: L
authors.lastname: Tokgozoglu
authors.forename: Hilmi
authors.initials: H
authors.lastname: Ozkutlu
authors.forename: Ali
authors.initials: A
authors.lastname: Oto
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000502:physiology