Relationship between myocardial norepinephrine content and left ventricular function -- an endomyocardial biopsy study

To analyze the relationships between left ventricular function, catecholamine concentrations in plasma and myocardium, and morphological alterations, 20 patients were studied. Fifteen patients had idiopathic dilated cardiomyopathy, and 5 had normal left ventricular function. All patients underwent right ventricular endomyocardial biopsy to determine muscle fibre thickness, percent volume fraction of interstitium, and myocardial catecholamine content. Blood was sampled to measure plasma catecholamine concentrations, and left ventricular cineangiography was performed to determine global ejection fraction. In a simple correlation analysis a significant correlation was found between left ventricular ejection fraction and myocardial norepinephrine content (r = 0.80, P less than 0.001). Left ventricular ejection fraction was negatively correlated with plasma epinephrine concentration (r- = 0.53, P less than 0.02), and with muscle fibre thickness (r = -0.50, P less than 0.03). Myocardial norepinephrine concentration was negatively correlated with plasma epinephrine (r = -0.62, P less than 0.01). Multiple linear regression analysis revealed a strong correlation between myocardial norepinephrine depletion and left ventricular dysfunction, which was independent of all other variables. These data suggest that myocardial norepinephrine depletion determined from right ventricular endomyocardial biopsies strongly correlates with left ventricular dysfunction in idiopathic dilated cardiomyopathy, and seems to be independent of the degree of muscle fibre hypertrophy, volume fraction of interstitium, and of the increased sympathetic tone.