In patients with severe left ventricular dysfunction, dobutamine stress testing is a useful diagnostic tool to evaluate decreased myocardial contractile reserve, according to a study in the November issue of the Journal of the American College of Cardiology: Cardiovascular Imaging.
Catecholamine sensitivity is reduced in failing hearts as a result of myocardial abnormalities in the beta-adrenergic receptor signaling pathway. However, little is known about adrenergic myocardial contractile reserve in asymptomatic or mildly symptomatic patients with dilated cardiomyopathy, according to background information in the study.
Using dobutamine stress testing, Masakazu Kobayashi, MD, of Nagoya University Graduate School of Medicine in Japan, and colleagues studied 46 dilated cardiomyopathy patients.
The investigators found that there was a reduced adrenergic myocardial contractile reserve in all patients with severe left ventricular systolic dysfunction (ejection fraction less than or equal to 25 percent).
“The fact that these changes were observed in relatively early stages of heart failure, and were more marked in those patients with reduced myocardial contractile reserve, would suggest that changes observed at the molecular level may actually be the cause of at least some of the impairment in left ventricular function,” wrote Gary S. Francis, MD, and Milind Y. Desai, MD, of Cleveland Clinic Heart and Vascular Institute, in an accompanying editorial.