Author + information
- Received March 14, 1994
- Revision received May 26, 1994
- Accepted June 2, 1994
- Published online November 1, 1994.
- Eric J. Eichhorn, MD, FACC∗,
- Christian M. Heesch, MD,
- James H. Barnett, MD,
- Luis G. Alvarez, MD,
- Steven M. Fass, MD,
- Paul A. Grayburn, MD, FACC,
- Barbara A. Hatfield, RN,
- Lucille G. Marcoux, RN and
- Craig R. Malloy, MD
- ↵∗Address for correspondence: Dr. Eric J. Eichhorn, Director, Cardiac Catheterization Laboratory (IIIA2), University of Texas Southwestern and Dallas Veterans Administration Medical Centers, 4500 South Lancaster, Dallas, Texas 75216.
Objectives. This study examined the of metoprolol on left ventricular performance, efficiency, neurohormonal activation and myocardial respiratory quotient in patients with dilated cardiomyopathy.
Background.The mechanism by which beta-adrenergie blockade improves ejection fraction in patients with dilated cardiomyopathy remains an enigma. Thus, we undertook an extensive hemodynamic evaluation of this mechanism. In addition, because animal models have shown that catecholamine exposure may increase relative fatty acid utilization, we hypothesized that antagonism of sympathetic stimulation may result in increased carbohydrate utilization.
Methods. This was a randomized, double-blind, prospective trial in which 24 men with nonischemic dilated cardiomyopathy underwent cardiac catheterization before and after 3 months of therapy with metoprolol (n = 15) or placebo (n = 9) in addition to standard therapy. Pressure-volume relations were examined using a micromanometer catheter and digital ventriculography.
Results. At baseline, the placebo-treated patients had somewhat more advanced left ventricular dysfunction. Ejection fraction and left ventricular performance improved only in the metoprolol-treated patients. Stroke and minute work increased without an increase in myocardial oxgen consumption, suggesting increased myocardial efficiency. Further increases in ejection fraction were seen between 3 and 6 months in the metoprolol group. The placebo group had a significant increase in ejection fraction only after crossover to metoprolol. A significant relation the change in coronary sinus norepinephrine and myocardial respiratory quotient was seen, suggesting a possible effect of adrenergic deactivation on substrate utilization.
Conclusions. These data demonstrate that in patients with cardiomyopthy, metoprolol treatment improves myocardial performance and energetics, and favorably alters substrate utilization. Beta-adrenergic blocking agents, such as metoprolol, are hemodynamically and energetically beneficial in the treatment of myocardial failure.
☆ This study was supported in part by Grant HL-17669 from the National Heart, Lung, and Blood Institute Ischemic Specialized Centers of Research, National Institutes of Health, Bethesda, Maryland.
- Received March 14, 1994.
- Revision received May 26, 1994.
- Accepted June 2, 1994.