Hemodynamic comparison of twice daily metoprolol tartrate with once daily metoprolol succinate in congestive heart failure

OBJECTIVES To compare the hemodynamic effects of twice daily metoprolol tar trate (MT) and once daily metoprolol succinate (MS) in congestive heart fai lure patients. BACKGROUND Adverse hemodynamic effects with MT demonstrated during initiati on persist with drug readministration during chronic therapy. METHODS Patients were randomly assigned to 6.25 mg MT or 25 mg MS orally an d the dose was gradually increased to a target of 50 mg twice a day or 100 mg once a day, respectively. Hemodynamic measurements were obtained at base line and after three months of therapy-both before and after drug readminis tration. RESULTS Long term metoprolol therapy produced significant functional, exerc ise and hemodynamic benefits with no difference in response between either metoprolol preparation in the 27 patients (MT [14], MS [13]). When full dos e metoprolol was readministered during chronic therapy, there were parallel adverse hemodynamic effects in both drug groups. Cardiac index decreased b y 0.6 liters/min/m(2) (p < 0.0001) with MT and by 0.5 liters/min/m(2) (p < 0.0001) with MS. Systematic vascular resistance increased by 253 dyne-sec-c m(-5) (p < 0.001) with MT and by 267 dyne-sec-cm(-5) (p < 0.0005) with MS. Stroke volume index decreased by 7.0 ml/m(2) (p < 0.0005) with MT and by 6. 5 ml/m(2) (p < 0.0001) with MS, while SVC;I decreased by 6.2 g-m/m(2) (p < 0.0005) with MT and by 6.0 g-m/m(2) (p < 0.001) with MS. CONCLUSION Metoprolol tartrate and MS produce similar hemodynamic and clini cal effects acutely and chronically despite the fourfold greater starting d ose of MS used in this study. A more rapid initiation with readily availabl e starting doses of MS may offer distinct advantages compared with MT in tr eating chronic heart failure patients with beta-adrenergic blocking agents. (C) 1999 by the American College of Cardiology.