Institute of Cellular Medicine, Newcastle Magnetic Resonance Centre, Medical School, Newcastle University, Newcastle upon Tyne, UK.
Cardiothoracic Department, James Cook University Hospital, Middleborough, UK.
Heart. 2018 Jan;104(2):111-118. doi: 10.1136/heartjnl-2017-311275. Epub 2017 Jun 12.
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.
Thirty-five healthy women (young≤50 years, n=20; and old≥60 years, n=15) underwent cardiac MRI with P 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.
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).
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.
心脏高能磷酸代谢（磷酸肌酸与三磷酸腺苷（PCr：ATP）比值）随年龄的降低以及心脏动力的降低可能在心脏功能障碍和心力衰竭的发展中发挥重要作用。本研究旨在明确年龄对 PCr：ATP 比值和心脏动力的影响及其关系。
35 名健康女性（年轻组≤50 岁，n=20；老年组≥60 岁，n=15）接受心脏 MRI 磷谱分析以评估 PCr：ATP 比值，并进行最大分级心肺运动试验，同时进行气体交换和中心血液动力学测量。峰值心输出量与平均动脉血压的乘积被计算为峰值运动心输出量，作为心脏泵血能力和性能的最佳衡量指标。
与年轻组相比，老年组的 PCr：ATP 比值显著降低（1.92±0.48 比 2.29±0.55，p=0.03），峰值心输出量（3.35±0.73 比 4.14±0.81W，p=0.01）、舒张功能（即早期到晚期舒张充盈比，1.33±0.54 比 3.07±1.84，p<0.01）和峰值运动耗氧量（1382.9±255.0 比 1940.3±434.4 mL/min，p<0.01）也降低。进一步分析表明，PCr：ATP 比值与早期到晚期舒张充盈比（r=0.46，p=0.02）、峰值心输出量（r=0.44，p=0.02）和峰值耗氧量（r=0.51，p=0.01）呈显著正相关。
高能磷酸代谢和心脏峰值动力随年龄增长而下降。PCr：ATP 比值与早期到晚期舒张充盈比和峰值心输出量之间呈显著正相关，提示心脏高能磷酸代谢可能是心脏功能和性能的重要决定因素。
