Objective Diminished cardiac high-energy phosphate metabolism (phosphocreatine-to-ATP (PCr:ATP) ratio) and cardiac power with age may play an important roles in development of cardiac dysfunction and heart failure. The study defines the impact of age on PCr:ATP ratio and cardiac power and their relationship.
Methods Thirty-five healthy women (young≤50 years, n=20; and old≥60 years, n=15) underwent cardiac MRI with 31P spectroscopy to assess PCr:ATP ratio and performed maximal graded cardiopulmonary exercise testing with simultaneous gas-exchange and central haemodynamic measurements. Peak cardiac power output, as the best measure of pumping capability and performance of the heart, was calculated as the product of peak exercise cardiac output and mean arterial blood pressure.
Results PCr:ATP ratio was significantly lower in old compared with young age group (1.92±0.48 vs 2.29±0.55, p=0.03), as were peak cardiac power output (3.35±0.73 vs 4.14±0.81W, p=0.01), diastolic function (ie, early-to-late diastolic filling ratio, 1.33±0.54 vs 3.07±1.84, p<0.01) and peak exercise oxygen consumption (1382.9±255.0 vs 1940.3±434.4 mL/min, p<0.01). Further analysis revealed that PCr:ATP ratio shows a significant positive relationship with early-to-late diastolic filling ratio (r=0.46, p=0.02), peak cardiac power output (r=0.44, p=0.02) and peak oxygen consumption (r=0.51, p=0.01).
Conclusions High-energy phosphate metabolism and peak power of the heart decline with age. Significant positive relationship between PCr:ATP ratio, early-to-late diastolic filling ratio and peak cardiac power output suggests that cardiac high-energy phosphate metabolism may be an important determinant of cardiac function and performance.
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Contributors DJ designed the study, collected and analysed data, and drafted the manuscript. MN and KGH contributed to data collection, analysis and interpretation, drafted the manuscript and approved the manuscript for submission. MIT, CE, MB, LV, PMS, GAM and DMT contributed to the study design, critically revised and approved the manuscript for submission.
Funding This study was funded by the Newcastle National Institute for Health Research (NIHR) Biomedical Research Centre in Ageing and Chronic Conditions and Newcastle MRC Centre for Ageing and Vitality. KGH is supported by the UK Medical Research Council (G1100160), MIT by NIHR Senior Research Fellowship, LV by the Serbian Ministry of Education, Science and Technological Development (III41007 and ON174028) and EC HORIZON2020 SMARTool project (689068), and DGJ by Research Councils UK Centre for Ageing and Vitality (L016354).
Competing interests None declared.
Patient consent Obtained.
Ethics approval North East of England - Tyne and Wear South.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data are included in this manuscript.
Correction notice This paper has been amended since it was published Online First. Owing to a scripting error, some of the publisher names in the references were replaced with ’BMJ Publishing Group'. This only affected the full text version, not the PDF. We have since corrected these errors and the correct publishers have been inserted into the references.
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