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Original research article
Heritability of resting heart rate and association with mortality in middle-aged and elderly twins
  1. Magnus T Jensen1,
  2. Mette Wod2,3,
  3. Søren Galatius4,
  4. Jacob B Hjelmborg2,
  5. Gorm B Jensen5,6,
  6. Kaare Christensen2,3,7
  1. 1Department of Cardiology, Rigshospitalet, Copenhagen, Denmark
  2. 2The Danish Twin Registry, Department of Public Health, University of Southern Denmark, Odense, Denmark
  3. 3Department of Public Health, The Danish Aging Research Center, University of Southern Denmark, Odense C, Denmark
  4. 4Department of Cardiology, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark
  5. 5The Copenhagen City Heart Study, Copenhagen University Hospital Frederiksberg, Frederiksberg, Denmark
  6. 6National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
  7. 7Department of Clinical Genetics, Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark
  1. Correspondence to Dr Magnus T Jensen, Department of Cardiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark; magnustjensen{at}gmail.com

Abstract

Objective Resting heart rate (RHR) possibly has a hereditary component and is associated with longevity. We used the classical biometric twin study design to investigate the heritability of RHR in a population of middle-aged and elderly twins and, furthermore, studied the association between RHR and mortality.

Methods In total, 4282 twins without cardiovascular disease were included from the Danish Twin Registry, hereof 1233 twin pairs and 1816 ‘single twins’ (twins with a non-participating co-twin); mean age 61.7 (SD 11.1) years; 1334 (31.2%) twins died during median 16.3 (IQR 13.8–16.5) years of follow-up assessed through Danish national registers. RHR was assessed by palpating radial pulse.

Results Within pair correlations for RHR adjusted for sex and age were 0.23 (95% CI 0.14 to 0.32) and 0.10 (0.03 to 0.17) for RHR in monozygotic (MZ) and dizygotic (DZ) twin pairs, respectively. Overall, heritability estimates were 0.23 (95% CI 0.15 to 0.30); 0.27 (0.15 to 0.38) for males and 0.17 (0.06 to 0.28) for females. In multivariable models adjusting for age, gender, body mass index, diabetes, hypertension, pulmonary function, smoking, physical activity and zygosity, RHR was significantly associated with mortality (eg, RHR >90 vs 61–70 beats per min: all-cause HR 1.56 (95% CI 1.21 to 2.03); cardiovascular 2.19 (1.30 to 3.67). Intrapair twin comparison revealed that the twin with the higher RHR was significantly more likely to die first and the probability increased with increase in intrapair difference in RHR.

Conclusions RHR is a trait with a genetic influence in middle-aged and elderly twins free of cardiovascular disease. RHR is independently associated with longevity even when familial factors are controlled for in a twin design.

  • Resting heart rate
  • longevity
  • cardiovascular
  • twin study
  • heritability
  • mortality

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Footnotes

  • Contributors MTJ made substantial contributions to the conception, analysis, interpretation of the data, drafting the work and revising it critically for important intellectual content, performed final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved. MW made substantial contributions to the analysis, interpretation of the data, drafting the work and revising it critically for important intellectual content, performed final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved. SG and JH made substantial contributions to the analysis, interpretation of the data and revising it critically for important intellectual content, performed final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved. GBJ made substantial contributions to the conception, interpretation of the data and revising it critically for important intellectual content, performed final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved. KC made substantial contributions to the conception, acquisition, analysis, interpretation of the data and revising it critically for important intellectual content, performed final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved.

  • Funding The Danish Twin Registry and the Danish Aging Research Center have received grants from the National Program for Research Infrastructure, the Danish Agency for Science Technology and Innovation, Copenhagen, Denmark, 2007 (grant no. 09–0 63 256), the VELUX Foundation, Copenhagen, Denmark and the US National Institutes of Health, Bethesda, Maryland (grant no. P01 AG08761).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Enquiries about statistical code can be directed to the corresponding author.

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