β-Adrenergic contractile reserve as a predictor of clinical outcome in patients with idiopathic dilated cardiomyopathy

Abstract

To examine the ability of β-adrenergic contractile reserve assessment to predict the outcome of patients with heart failure, a prospective study was undertaken in 35 patients with idiopathic dilated cardiomyopathy and radionuclide ejection fraction below 40%. During right- and left-sided catheterization, right atrial and left ventricular (LV) pressures, peak positive LV dp dt , cardiac index, and plasma norepinephrine and epinephrine concentrations were measured at baseline. After a left main intracoronary infusion of dobutamine (25 to 200 μg · min −1), β-adrenergic contractile responsiveness was assessed as the net increase in peak positive LV dp dt (Δ LV dp dt ). After the initial examination, patients were treated with diuretics, digitalis, and angiotensin converting enzyme inhibitors and then followed-up. After a mean follow-up period of 13 ± 7 months, two groups of patients were distinguished: those who responded to medical therapy (group A, n = 26) and those with clinical deterioration (group B, n = 9) leading to death ( n = 4) or heart transplantation ( n = 5). Initial peak positive LV dp dt , LV end-diastolic pressure, cardiac index, and LV ejection fraction were better in group A than in group B ( p < 0.001). Initial plasma norepinephrine and epinephrine concentrations were significantly higher and Δ LV dp dt was lower in group B than in group A ( p < 0.001). Multivariate stepwise logistic regression analysis showed that Δ LV dp dt ( p < 0.0001) and LV ejection fraction ( p = 0.0001) were independently related to prognosis. At threshold values of either 250 mm Hg · sec −1 for Δ LV dp dt or 20% for LV ejection fraction, their prognostic predictive values were 69% and 53%, respectively. When the same threshold values were used, a combination of these two parameters led to a positive predictive value of 100%. In conclusion, patients who do not respond to medical therapy were those with the lowest β-adrenergic contractile reserve. Regarding clinical outcome, low- and high-risk populations may be discriminated by combining LV ejection fraction and β-adrenergic contractile reserve assessment.