Impact of exercise capacity on myocardial high-energy phosphate metabolism.
31-Phosphorous magnetic resonance spectroscopy (31P MRS) is a unique tool to investigate IN VIVO high-energy phosphates (HEP) in the human heart. We hypothesized that physical capacity may be associated with myocardial HEP status. Healthy, male volunteers (n = 105, mean age 51 +/- 7 years) underwent bicycle ergometry with a stepwise increasing workload to determine maximal working capacity (MWC). Heart rate (HR) and blood pressure (BP) were measured continuously during exercise and 4 minutes of recovery. Further 31-Phosphorous 2-dimensional chemical shift imaging (31P 2D CSI) MRS was performed to assess myocardial HEP metabolism by determining phosphocreatinine to beta-ATP ratios (PCr/b-ATP) using a 1.5 tesla scanner. Volunteers with MWC > 230 Watt had significantly higher PCr/b-ATP ratios than those with MWC < 200 Watt (1.93 +/- 0.36 vs. 1.59 +/- 0.35; p < 0.001). Additionally, those with a recovery systolic (S)BP < 195 mmHg had significantly higher ratios than those with a recovery SBP > 195 mmHg (1.74 +/- 0.3 vs. 1.51 +/- 0.2; p < 0.05). We observed a linear correlation between the PCr/b-ATP ratio and MWC (r = 0.411; p < 0.001) and recovery SBP (r = - 0.290; p < 0.01). After statistical correction for age, these correlations remained significant. In this study, we observed a correlation of parameters of physical fitness determined by bicycle exercise testing and cardiac PCr/b-ATP ratios.
Klug
G
G
Department of Cardiology, University Hospital Innsbruck, Innsbruck, Austria.
Zwick
R H
RH
Frick
M
M
Wolf
C
C
Schocke
M F H
MF
Conci
E
E
Jaschke
W
W
Pachinger
O
O
Metzler
B
B
D000328:Adult; D001317:Austria; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism*
D010725:Phosphocreatine