Effect on the myocardial energy metabolism of angiotensin-converting enzyme inhibition in chronic heart failure.

There is substantial evidence that the failing heart is in an energy-depleted state. The imbalance between myocardial oxygen supply and demand might be the cause for adaptive metabolic changes seen in patients with severe chronic heart failure. By analyzing the lactate dehydrogenase (LDH) isoenzyme pattern, an increase of LDH5 and a decrease of LDH1 was seen in myocardium from patients with chronic heart failure. Additionally, the concentration of the adenosine diphosphate (ADP)/adenosine triphosphate (ATP) carrier was significantly elevated. After treatment with the angiotensin-converting enzyme inhibitor enalapril in 33 patients with chronic heart failure, LDH1 increased from 38.7 +/- 6.7 to 42.3 +/- 5.5 (p less than 0.005), paralleled by a decrease in LDH5 from 20.8 +/- 7.0 to 15.8 +/- 4.7 (p less than 0.001). The ADP/ATP carrier concentration also decreased significantly within the normal range. There was a good correlation between the hemodynamic data and the LDH isoenzyme pattern. The shift of the LDH isoenzyme pattern and the decrease of the ADP/ATP concentration can be taken as an indication for an improvement of the myocardial energy balance in chronic heart failure with angiotensin-converting enzyme inhibitor therapy.