Effect of pimobendan in patients with chronic heart failure

To assess the effects of a calcium sensitizer, pimobendan, in patients with mild to moderate chronic heart failure. Pimobendan was administered at a dose of 2.5 mg/day for 12 months to 34 patients with chronic heart failure (New York Heart Association functional class IIm to III) after treatment with diuretics and angiotensin-converting enzyme inhibitors. The etiologies of heart failure were dilated cardiomyopathy (DCM), old myocardial infarction (OMI) and other heart disease (Others). The effects of pimobendan were assessed by echocardiography, blood pool scintigraphy, Holter monitoring, (123)I-meta-iodobenzylguanidine (MIBG) imaging and (123)I-beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) imaging. Pimobendan produced improvement of symptoms in the majority of patients. Improvement was more common in the DCM group than in the OMI group. Left ventricular internal diameter measured by echocardiography was significantly decreased. Left ventricular ejection fraction was significantly increased in the DCM and Others groups. The heart to mediastinum ratio on MIBG imaging was significantly increased in the DCM and Others groups, and the heart to mediastinum ratio on BMIPP imaging was significantly increased in the DCM group. Pimobendan is effective in patients with chronic heart failure but is less effective in patients with OMI than in patients with DCM or other heart diseases.