INVASIVE PHARMACODYNAMIC CHARACTERIZATION OF COMBINED IBOPAMINE AND CALCIUM BLOCKER THERAPY FOR HEART-FAILURE

Study Objective. To determine the acute hemodynamic response of single -dose coadministration of ibopamine plus nifedipine or diltiazem in pa tients with New York Heart Association functional class (NYHA FC) II-I II congestive heart failure. Design. A single-blind, placebo-controlle d, two-paired, crossover study. Setting. Cardiology clinics at two lar ge teaching hospitals. Patients. Eight patients with NYHA FC II-III co ngestive heart failure who met the inclusion criteria were selected ra ndomly. Interventions. All patients underwent right heart catheterizat ion. Day 1 consisted of concomitant calcium channel blocker plus place bo, with cardiac and peripheral hemodynamic recordings from 30 minutes -24 hours. The design was equivalent on day 2, with single-dose admini stration of ibopamine plus calcium channel blocker. Measurements and M ain Results. Single-dose nifedipine-diltiazem augmented cardiac output and stroke volume secondary to decreasing systemic vascular resistanc e. The nifedipine-ibopamine and diltiazem-ibopamine subgroups demonstr ated relatively equal hemodynamics, augmenting cardiac index (nifedipi ne 43%, p<0.05; diltiazem 40%, p<0.05 vs baseline) while decreasing sy stemic vascular resistance (nifedipine 41%, p<0.05; diltiazem 28%, p N S vs baseline) 30 minutes after the dose. In contrast to single-dose d iltiazem, the diltiazem-ibopamine subgroup exhibited an increased left ventricular filling pressure (122%, p<0.05 vs baseline) and mean pulm onary artery pressure (43%, p<0.05 vs baseline) at 30 minutes after th e dose. One patient experienced a transient episode of chest pain asso ciated with increased heart rate and blood pressure with diltiazem-ibo pamine. Conclusion. Diltiazem and ibopamine should be coadministered w ith caution in patients with coronary artery disease and left ventricu lar dysfunction.