title: Heart Rate Variability Is Associated with Exercise Capacity in Patients with Cardiac Syndrome X.
abstract: Heart rate variability (HRV) reflects the healthiness of autonomic nervous system, which is associated with exercise capacity. We therefore investigated whether HRV could predict the exercise capacity in the adults with cardiac syndrome X (CSX). A total of 238 subjects (57±12 years, 67.8% men), who were diagnosed as CSX by the positive exercise stress test and nearly normal coronary angiogram were enrolled. Power spectrum from the 24-hour recording of heart rate was analyzed in frequency domain using total power (TP) and spectral components of the very low frequency (VLF), low frequency (LF) and high frequency (HF) ranges. Among the study population, 129 subjects with impaired exercise capacity during the treadmill test had significantly lower HRV indices than those with preserved exercise capacity (≥90% of the age predicted maximal heart rate). After accounting for age, sex, and baseline SBP and heart rate, VLF (odds ratio per 1SD and 95% CI: 2.02, 1.19-3.42), LF (1.67, 1.10-2.55), and TP (1.82, 1.17-2.83) remained significantly associated with preserved exercise capacity. In addition, increased HRV indices were also associated with increased exercise duration, rate-pressure product, and heart rate recovery, independent of age, body mass index, and baseline SBP and heart rate. In subgroup analysis, HRV indices demonstrated similar predictive values related to exercise capacity across various subpopulations, especially in the young. In patients with CSX, HRV was independently associated with exercise capacity, especially in young subjects. The healthiness of autonomic nervous system may have a role in modulating the exercise capacity in patients with CSX.
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.|Department of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Dai-Yin
authors.initials: DY
authors.lastname: Lu
authors.affiliation: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Medicine, National Yang-Ming University, Taipei, Taiwan.|Research Center for Adaptive Data Analysis, National Central University, Taoyuan, Taiwan.
authors.forename: Albert C
authors.initials: AC
authors.lastname: Yang
authors.affiliation: Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Hao-Min
authors.initials: HM
authors.lastname: Cheng
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Tse-Min
authors.initials: TM
authors.lastname: Lu
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wen-Chung
authors.initials: WC
authors.lastname: Yu
authors.affiliation: Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Medicine, National Yang-Ming University, Taipei, Taiwan.|Department of Public Health, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chen-Huan
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Medicine, National Yang-Ming University, Taipei, Taiwan.|Department of Public Health, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Shih-Hsien
authors.initials: SH
authors.lastname: Sung
mesh_terms: D000368:Aged; D000465:Algorithms; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D017566:Microvascular Angina / Q000503:physiopathology*; D008875:Middle Aged; D011446:Prospective Studies
references.citation: Eur Heart J. 1999 Nov;20(22):1638-46
references.pmid: 10543927
references.citation: J Am Coll Cardiol. 2003 Nov 19;42(10):1767-76
references.pmid: 14642686
references.citation: Heart. 2000 Mar;83(3):290-4
references.pmid: 10677408
references.citation: Ital Heart J. 2000 Mar;1(3):221-5
references.pmid: 10806990
references.citation: Circulation. 2000 Jun 13;101(23):E215-20
references.pmid: 10851218
references.citation: Auton Neurosci. 2001 Jul 20;90(1-2):66-75
references.pmid: 11485294
references.citation: Circulation. 2001 Oct 16;104(16):1911-6
references.pmid: 11602493
references.citation: Cardiovasc Res. 2001 Nov;52(2):208-16
references.pmid: 11684068
references.citation: Am J Cardiol. 1973 Sep 7;32(3):375-6
references.pmid: 4725594
references.citation: J Appl Physiol. 1975 Nov;39(5):801-5
references.pmid: 1184518
references.citation: Science. 1981 Jul 10;213(4504):220-2
references.pmid: 6166045
references.citation: Circulation. 1985 Feb;71(2):218-26
references.pmid: 3965167
references.citation: Am J Physiol. 1985 Jan;248(1 Pt 2):H151-3
references.pmid: 3970172
references.citation: J Am Coll Cardiol. 1986 Aug;8(2):459-61
references.pmid: 3734269
references.citation: Br Heart J. 1994 Jan;71(1):1-2
references.pmid: 8297682
references.citation: Am J Cardiol. 1994 Jun 15;73(16):1174-9
references.pmid: 8203334
references.citation: J Am Coll Cardiol. 1995 Mar 15;25(4):807-14
references.pmid: 7884081
references.citation: Eur Heart J. 1995 Apr;16(4):490-5
references.pmid: 7671894
references.citation: Circulation. 1996 Mar 1;93(5):1043-65
references.pmid: 8598068
references.citation: Eur Heart J. 1995 Nov;16(11):1571-7
references.pmid: 8881850
references.citation: Am J Cardiol. 1998 Apr 1;81(7):834-40
references.pmid: 9555771
references.citation: Circulation. 1998 Aug 11;98(6):547-55
references.pmid: 9714112
references.citation: Am J Cardiol. 1998 Oct 1;82(7):862-8
references.pmid: 9781968
references.citation: Am J Cardiol. 1998 Nov 15;82(10):1236-41
references.pmid: 9832101
references.citation: Int J Cardiol. 1998 Oct 30;66(3):253-60
references.pmid: 9874077
references.citation: J Am Soc Nephrol. 2006 Oct;17(10):2937-44
references.pmid: 16988059
references.citation: Eur J Appl Physiol. 2007 Jun;100(3):363-9
references.pmid: 17440748
references.citation: Int J Cardiol. 2010 Nov 19;145(2):312-4
references.pmid: 19962772
references.citation: Pediatr Cardiol. 2011 Dec;32(8):1158-63
references.pmid: 21739302
references.citation: Congest Heart Fail. 2012 Jul-Aug;18(4):192-7
references.pmid: 22536936
references.citation: Circulation. 2014 May 27;129(21):2100-10
references.pmid: 24799513
references.citation: Pacing Clin Electrophysiol. 2009 Mar;32 Suppl 1:S113-5
references.pmid: 19250071
references.citation: Am J Physiol. 1999 Dec;277(6 Pt 2):H2233-9
references.pmid: 10600841
references.citation: Int J Cardiol. 2014 Jul 1;174(3):857-60
references.pmid: 24804906
references.citation: JAMA. 2009 Apr 8;301(14):1439-50
references.pmid: 19351941