Author + information
- Received August 5, 1994
- Revision received December 23, 1994
- Accepted January 9, 1995
- Published online May 1, 1995.
- David S. Bach, MD, FACC*,
- Rob S.B. Beanlands, MD, FRCPC1,
- Markus Schwaiger, MD, FACC and
- William F. Armstrong, MD, FACC
- ↵*Address for correspondence: Dr. David S. Bach. University of Michigan, UH 9D9800-0119, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109.
Objectives. This study was performed to test the hypothesis that regional variation in ventricular function in patients with nonischemic dilated cardiomyopathy is related to regional variation in oxidative metabolism.
Background. Heterogeneity in regional left ventricular function has long been noted in patients with nonischemic dilated cardiomyopathy. Regional variation in wall stress has been proposed as the pathophysiologic mechanism. By correlating regional function with oxidative metabolism, one can test the hypothesis that heterogeneity in wall stress is responsible for heterogeneity in function. We hypothesized that preserved function as a result of more favorable loading conditions would be associated with regional oxidative metabolism that is equal to or lower than that in other regions.
Methods. Fifteen patients with nonischemic dilated cardiomyopathy (mean [±SD] ejection fraction 20.7 ± 4.0%) were studied. Regional ventricular function was determined using short-axis chordal shortening on two-dimensional echocardiography. Regional oxidative metabolism was assessed by carbon-11 acetate clearance kinetics on dynamic positron emission tomography. An eight-segment model of the left ventricle was used. Segmental function and oxidative metabolism were defined as increased if they varied at least 1 SD from the respective mean value for that patient.
Results. Thirteen (87%) of 15 patients exhibited segments with increased function. In 7 (54%) of 13 patients, regional function was increased in the proximal lateral wall. Multivariate linear regression analysis showed a direct relation between regional function and oxidative metabolism (p = 0.02). The average concordance between increased function and increased oxidative metabolism among patients was 0.87 ± 0.11 (95% confidence interval 0.70 to 1.00).
Conclusions. Patients with nonischemic dilated cardiomyopathy display heterogeneity in regional ventricular function. Relative preservation is observed most frequently in the proximal lateral wall. Relative preservation of function is associated with higher regional oxidative metabolism, suggesting that mechanisms other than or in addition to local loading conditions may be responsible for heterogeneity in function.
↵1 Dr. Beanlands was a research fellow supported by the Medical Research Council of Canada Centennial Fellowship, Ottawa, Ontario, Canada from July 1, 1991 to September 30, 1992.
This work was carried out during the tenure of Dr. Schwaiger as an Established Investigator of the American Heart Association, Dallas, Texas and was supported in part by Grants RO1 HL41047-01 and MO1 RR00042 from the National Heart, Lung, and Blood Institute. National Institutes of Health, Bethesda, Maryland through the Kughn Clinical Research Center, Ann Arbor, Michigan.
- Received August 5, 1994.
- Revision received December 23, 1994.
- Accepted January 9, 1995.
- American College of Cardiology