Jari A Laukkanen1, Sudhir Kurl2, Hassan Khan3, Setor K Kunutsor4. 1. Institute of Clinical Medicine, Department of Medicine, University of Eastern Finland, Kuopio, Finland; Central Finland Health Care District, Department of Medicine, Jyväskylä, Finland; Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland. Electronic address: jariantero.laukkanen@uef.fi. 2. Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland. 3. Section of Cardiac Electrophysiology, The Leon H. Charney Division of Cardiology, NYU Langone Health, NYU Robert I. Grossman School of Medicine, New York, USA. 4. National Institute for Health Research Bristol Biomedical Research Centre, University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol, Bristol, United Kingdom; Translational Health Sciences, Bristol Medical School, University of Bristol, Learning & Research, Southmead Hospital, Bristol, United Kingdom.
Abstract
BACKGROUND: The inverse associations between cardiorespiratory fitness (CRF) and vascular outcomes have been established. However, there has been no prospective evaluation of the relationship between percentage of age-predicted cardiorespiratory fitness (%age-predicted CRF) and risk of sudden cardiac death (SCD). OBJECTIVE: The purpose of this study was to assess the association of %age-predicted CRF with SCD risk in a long-term prospective cohort study. METHODS: CRF was assessed using the gold standard respiratory gas exchange analyzer in 2276 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (Achieved CRF/Age-predicted CRF) × 100. Hazard ratios (HRs) [95% confidence intervals (CIs)] were calculated for SCD. RESULTS: During median follow-up of 28.2 years, 260 SCDs occurred. There was a dose-response relationship between age-predicted CRF and SCD. A 1-SD increase in %age-predicted CRF was associated with a decreased risk of SCD in analysis adjusted for established risk factors (HR 0.60; 95% CI 0.53-0.70), which remained consistent on further adjustment for several potential confounders, including alcohol consumption, physical activity, socioeconomic status, and systemic inflammation (HR 0.73; 95% CI 0.62-0.85). The corresponding adjusted HRs were 0.34 (0.23-0.50) and 0.52 (0.34-0.79), respectively, when comparing extreme quartiles of %age-predicted CRF levels. HRs for the associations of absolute CRF levels with SCD risk in the same participants were similar. CONCLUSION: Percentage of age-predicted CRF is continuously, strongly, and independently associated with risk of SCD and is comparable to absolute CRF as a risk indicator for SCD.
BACKGROUND: The inverse associations between cardiorespiratory fitness (CRF) and vascular outcomes have been established. However, there has been no prospective evaluation of the relationship between percentage of age-predicted cardiorespiratory fitness (%age-predicted CRF) and risk of sudden cardiac death (SCD). OBJECTIVE: The purpose of this study was to assess the association of %age-predicted CRF with SCD risk in a long-term prospective cohort study. METHODS: CRF was assessed using the gold standard respiratory gas exchange analyzer in 2276 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (Achieved CRF/Age-predicted CRF) × 100. Hazard ratios (HRs) [95% confidence intervals (CIs)] were calculated for SCD. RESULTS: During median follow-up of 28.2 years, 260 SCDs occurred. There was a dose-response relationship between age-predicted CRF and SCD. A 1-SD increase in %age-predicted CRF was associated with a decreased risk of SCD in analysis adjusted for established risk factors (HR 0.60; 95% CI 0.53-0.70), which remained consistent on further adjustment for several potential confounders, including alcohol consumption, physical activity, socioeconomic status, and systemic inflammation (HR 0.73; 95% CI 0.62-0.85). The corresponding adjusted HRs were 0.34 (0.23-0.50) and 0.52 (0.34-0.79), respectively, when comparing extreme quartiles of %age-predicted CRF levels. HRs for the associations of absolute CRF levels with SCD risk in the same participants were similar. CONCLUSION: Percentage of age-predicted CRF is continuously, strongly, and independently associated with risk of SCD and is comparable to absolute CRF as a risk indicator for SCD.