Acute and chronic effects of pirbuterol on left ventricular ejection fraction and clinical status in severe congestive heart failure

Abstract

To evaluate the long-term effectiveness of the orally active beta-adrenergic sympathomimetic agent pirbuterol (PBL) in patients with severe congestive heart failure (CHF) we assessed the effect of 4 weeks of PBL therapy on clinical status and left ventricular ejection fraction (LVEF) measured by gated blood pool scan in nine patients with New York Heart Association functional class III or IV symptoms. Three hours after the first administration of PBL (30 mg) LVEF increased from mean 0.20 ± 0.03 to 0.26 ± 0.04 (p < 0.01). Following 5 to 7 days of maintenance PBL therapy (20 mg three times daily) LVEF measured 2.5 hours after administration of PBL (30 mg) was 0.23 ± 0.03 (p = 0.19 vs pretreatment baseline). After 30 days of maintenance PBL therapy (20 mg three times dally) LVEF fraction 2.5 hours after administration of PBL (30 mg) was 0.19 ± 0.03 (p = NS vs pretreatment baseline). Serum PBL levels were higher during long-term PBL therapy than after the first administration of the drug. Despite lack of improvement in LVEF during long-term therapy, five of nine patients were subjectively improved from their pretreatment state. There were small increases in both frequency and grade of ventricular ectopic beats during chronic therapy, but in no case did arrhythmias limit therapy. The only side effect noted was tremulousness (three patients), which abated by the end of the first week of therapy in all cases. This study indicates that some but not all patients with CHF may respond clinically to chronic PBL administration. The initial effect on LVEF was attenuated during chronic therapy. Further studies are needed to determine any mechanism of hemodynamic attenuation and its relevance to clinical efficacy.