ABSTRACT
OBJECTIVES: The purpose of this study was to determine whether higher left ventricular inotropic reserve, defined as the increase in left ventricular ejection fraction (LVEF) in response to intravenous dobutamine infusion, or other ventriculographic variables predict the increase in LVEF after beta-blocker therapy in patients with nonischemic cardiomyopathy (NICM). BACKGROUND: Long-term beta-blocker therapy increases LVEF in some patients with NICM. Other than dose, there are no definite predictors of LVEF increase. METHODS: Thirty patients with LVEF < or = 0.35 and NICM underwent assessment of LVEF at rest and after a 10-min intravenous infusion of dobutamine at 10 microg/kg/min, using equilibrium radionuclide ventriculography. Age was 49 +/- 11 years, 33% women, functional class 2.6 +/- 0.5, duration of chronic heart failure 3.2 +/- 2.9 years, LVEF 0.21 +/- 0.07, left ventricular end-diastolic volume index 180 +/- 64 ml/m2. Right ventricular ejection fraction (RVEF) was abnormal in 37%. Mean dobutamine-induced augmentation of LVEF (DoALVEF) was 0.12 +/- 0.08. Patients were started on one of three beta-blockers (carvedilol, bucindolol or metoprolol) and the dose was advanced to the maximum tolerated. RESULTS: Left ventricular ejection fraction, reassessed 7.4 +/- 5.9 months after maximum beta-blocker dose was reached, increased to 0.34 +/- 0.13 (p = 0.0006). The following baseline variables correlated with improvement of LVEF: DoALVEF (p = 0.001), RVEF (p = 0.005), systolic blood pressure at end of dobutamine infusion (p = 0.02) and dose of beta-blocker (p = 0.07). In a multivariate analysis, only DoALVEF (p = 0.0003) and RVEF (p = 0.002) were predictive of the increase in LVEF. CONCLUSIONS: Patients with nonischemic cardiomyopathy who have higher left ventricular inotropic reserve and normal RVEF derive higher increase in LVEF from beta-blocker therapy.
Subject(s)
Cardiomyopathies/physiopathology , Stroke Volume/physiology , Ventricular Function, Left , Ventricular Function, Right , Adrenergic beta-Antagonists/therapeutic use , Adult , Aged , Cardiomyopathies/diagnostic imaging , Cardiomyopathies/drug therapy , Female , Humans , Male , Middle Aged , Radionuclide VentriculographyABSTRACT
AIMS: The prognosis of patients with severe non-ischaemic dilated cardiomyopathy is variable. The predictive value of currently utilized tests is suboptimal. The purpose of this study was to determine the prognostic value of dobutamine-induced augmentation of left ventricular ejection fraction in patients with non-ischaemic dilated cardiomyopathy. METHODS AND RESULTS: Sixty-two patients with left ventricular ejection fraction < or =0.30 underwent exercise testing with gas exchange analysis and assessment of left ventricular ejection fraction at rest and after a 10-min intravenous infusion of dobutamine at 10 microg x kg(-1) x min(-1), using equilibrium radionuclide ventriculography. Age was 48+/-11 years, 32% females, functional class 2.6+/-0.6, resting left ventricular ejection fraction 0.20+/-0.06, and peak exercise oxygen consumption (mVO2) 19+/-6 ml x kg(-1) x min(-1). Mean dobutamine-induced augmentation of left ventricular ejection fraction (DeltaLVEF) was 0.09+/-0.06 (median 0.08, range -0.03 to 0.26). Follow-up was 25+/-15 months during which there were 12 deaths and five transplantations. Patients were divided into two groups based on median DeltaLVEF. The transplant-free survival was better in the group with higher DeltaLVEF (94% vs 64%, P<0.008). In multivariate analysis incorporating age, gender, duration of chronic heart failure, functional class, right and left ventricular ejection fraction, DeltaLVEF, left ventricular end-diastolic volume index, and mVO2, only DeltaLVEF was predictive of 1-year, 3-year, and overall transplant-free survival (RR 0.09, 0.03, and 0.13;P 0.03, 0.09, and 0.08 respectively). The linear correlation between DeltaLVEF and mVO2(r=0.3) and between DeltaLVEF and left ventricular ejection fraction (r=0.5) was weak. CONCLUSION: Dobutamine-induced augmentation of left ventricular ejection fraction is a strong prognostic variable, independent of exercise capacity and resting ventriculographic variables, in severe non-ischaemic systolic dysfunctional heart failure.
