Myocardial phosphocreatine-to-ATP ratio is a predictor of mortality in patients with dilated cardiomyopathy.
BACKGROUND
In patients with heart failure due to dilated cardiomyopathy, cardiac energy metabolism is impaired, as indicated by a reduction of the myocardial phosphocreatine-to-ATP ratio, measured noninvasively by 31P-MR spectroscopy. The purpose of this study was to test whether the phosphocreatine-to-ATP ratio also offers prognostic information in terms of mortality prediction as well as how this index compares with well-known mortality predictors such as left ventricular ejection fraction (LVEF) or New York Heart Association (NYHA) class.


RESULTS
Thirty-nine patients with dilated cardiomyopathy were followed up for 928+/-85 days (2.5 years). At study entry, LVEF and NYHA class were determined, and the cardiac phosphocreatine-to-ATP ratio was measured by localized 31P-MR spectroscopy of the anterior myocardium. During the study period, total mortality was 26%. Patients were divided into two groups, one with a normal phosphocreatine-to-ATP ratio (>1.60; mean+/-SE, 1.98+/-0.07; n=19; healthy volunteers: 1.94+/-0.11, n=30) and one with a reduced phosphocreatine-to-ATP ratio (<1.60; 1.30+/-0.05; n=20). At re-evaluation (mean, 2.5 years), 8 of 20 patients with reduced phosphocreatine-to-ATP ratios had died, all of cardiovascular causes (total and cardiovascular mortality, 40%). Of the 19 patients with normal phosphocreatine-to-ATP ratios, 2 had died (total mortality, 11%), one of cardiovascular causes (cardiovascular mortality, 5%). Kaplan-Meier analysis showed significantly reduced total (P=.036) and cardiovascular (P=.016) mortality for patients with normal versus patients with low phosphocreatine-to-ATP ratios. A Cox model for multivariate analysis showed that the phosphocreatine-to-ATP ratio and NYHA class offered significant independent prognostic information on cardiovascular mortality.


CONCLUSIONS
The myocardial phosphocreatine-to-ATP ratio, measured noninvasively with 31P-MR spectroscopy, is a predictor of both total and cardiovascular mortality in patients with dilated cardiomyopathy.
Neubauer
S
S
Department of Medicine, Würzburg University, Germany. s.neubauer@rzbox.uni-wuerzburg.de
Horn
M
M
Cramer
M
M
Harre
K
K
Newell
J B
JB
Peters
W
W
Pabst
T
T
Ertl
G
G
Hahn
D
D
Ingwall
J S
JS
Kochsiek
K
K
D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism*; D000328:Adult; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000378:metabolism* / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015993:Life Tables; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000032:analysis / Q000378:metabolism*; D010758:Phosphorus; D011237:Predictive Value of Tests; D011379:Prognosis; D013997:Time Factors
D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate