Impact of aging on cardiac high-energy phosphate metabolism determined by phosphorus-31 2-dimensional chemical shift imaging (31P 2D CSI)

Previous echocardiographic and experimental animal studies have shown that cardiac function, structure, and metabolism change with age. The aim of this study was to evaluate the impact of age on left ventricular high-energy phosphate metabolism. Using a 1.5 Tesla whole-body MR scanner 31P 2D CSI (8 × 8 phase encoding steps, 320 mm field of view) was performed in 76 healthy male volunteers (41.7 ± 13 years) without any history of coronary heart disease. Fourier interpolation, corrections for T1 saturation effects, the nucleus Overhauser effect, and the blood contamination were applied to the spectroscopic data. The volunteers were divided into two groups, younger ( n = 37) and older ( n = 39) than 41.7 years. In all volunteers, laboratory specimen were sampled, and transthoracal echocardiography was carried out. Significant differences in left ventricular phosphocreatine (PCr) to β-adenosine-triphosphate (β-ATP) ratios (2.16 vs. 1.83, p < 0.001), fasting serum glucose levels (83.3 vs. 98.7 mg/dl, p < 0.001), E/A (1.51 vs. 1.14 p < 0.001), and ejection fraction (EF, 65.3 vs. 59.9%, p = 0.005) were detected between the two groups of volunteers, younger and older than 41.7 years. Moreover, age correlated moderately to well with left ventricular PCr to β-ATP ratios ( r = −0.44), fasting serum glucose levels ( r = 0.4), E/A ( r = −0.7), left ventricular myocardial mass ( r = −0.41), and EF ( r = −0.55). In conclusion, our study shows that left ventricular PCr to β-ATP ratios decrease moderately with age, as suggested by previous experimental animal studies. Additionally, age correlates negatively with E/A, left ventricular myocardial mass, and EF, as reported by previous echocardiography studies. The present study is the first to show the impact of age on left ventricular PCr to β-ATP values in humans.