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Submaximal fitness and mortality risk reduction in coronary heart disease: a retrospective cohort study of community-based exercise rehabilitation
  1. Claire Taylor1,
  2. Costas Tsakirides2,
  3. James Moxon3,
  4. James William Moxon4,
  5. Michael Dudfield5,
  6. Klaus K Witte6,
  7. Lee Ingle1,
  8. Sean Carroll1
  1. 1Department of Sport, Health and Exercise Science, University of Hull, Hull, UK
  2. 2Carnegie School of Sport, Leeds Beckett University, Leeds, UK
  3. 3Burton Croft Surgery, Leeds, UK
  4. 4Retired General Practitioner, Leeds, UK
  5. 5Retired Fitness Development Officer, Sports Development, Leeds Leisure Services, Leeds, UK
  6. 6Division of Cardiovascular and Diabetes Research, University of Leeds, Leeds, UK
  1. Correspondence to Claire Taylor; c.taylor6{at}hull.ac.uk

Abstract

Objectives To examine the association between submaximal cardiorespiratory fitness (sCRF) and all-cause mortality in a cardiac rehabilitation (CR) cohort.

Design Retrospective cohort study of participants entering CR between 26 May 1993 and 16 October 2006, followed up to 1 November 2013 (median 14 years, range 1.2–19.4 years).

Setting A community-based CR exercise programme in Leeds, West Yorkshire, UK.

Participants A cohort of 534 men (76%) and 136 women with a clinical diagnosis of coronary heart disease (CHD), aged 22–82 years, attending CR were evaluated for the association between baseline sCRF and all-cause mortality. 416 participants with an exercise test following CR (median 14 weeks) were examined for changes in sCRF and all-cause mortality.

Main outcome measures All-cause mortality and change in sCRF expressed in estimated metabolic equivalents (METs).

Results Baseline sCRF was a strong predictor of all-cause mortality; compared to the lowest sCRF group (<5 METs for women and <6 METs for men), mortality risk was 41% lower in those with moderate sCRF (HR 0.59; 95% CI 0.42 to 0.83) and 60% lower (HR 0.40; 95% CI 0.25 to 0.64) in those with higher sCRF levels (≥7 METs women and ≥8 METs for men). Although improvement in sCRF at 14 weeks was not associated with a significant mortality risk reduction (HR 0.91; 95% CI 0.79 to 1.06) for the whole cohort, in those with the lowest sCRF (and highest all-cause mortality) at baseline, each 1-MET improvement was associated with a 27% age-adjusted reduction in mortality risk (HR 0.73; 95% CI 0.57 to 0.94).

Conclusions Higher baseline sCRF is associated with a reduced risk of all-cause mortality over 14 years in adults with CHD. Improving fitness through exercise-based CR is associated with significant risk reduction for the least fit.

  • cardiac rehabilitation
  • submaximal exercise testing
  • cardiorespiratory fitness
  • CHD
  • survival

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/

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