Relation of Target Dose Adherence to One Year Mortality in Heart Failure with Reduced Ejection Fraction: A Substudy of SUGAR

Abstract

Introduction: Cardiac glycosides are the only available oral agents which have positive inotropic effects and do not increase myocardial oxygen consumption. We conducted a single center study of acute intravenous digoxin loading in patients with low output decompensated heart failure (HF) with hemodynamic monitoring. Hypothesis: Digoxin loading is safe and effective in improving cardiac index (CI) and decreasing the need for IV inotropic support in low output decompensated HF. Methods: A total of 10 patients with low output HF monitored with a Swan Ganz catheter were loaded with 1 mg of Digoxin over a 24 hour period. Loading dose was given intravenously as 0.5 mg followed by 0.25 mg in six hours and then 0.25 mg six hours later. Hemodynamic variables were obtained before and after digoxin loading. Safety end points included atrial and ventricular arrhythmias and digoxin level at 72 hours after loading. Results: Baseline echocardiographic and hemodynamic variables were consistent with advanced HF, with a mean LVEF of 15 +/5 %, a baseline mean CI of 1.67 L/min/m2 and a mean PCWP of 27.4 mm Hg. After Digoxin loading, CI improved by a mean of 60.1 % (0% to 135.7%) and PCWP decreased by 38.2% (11% to 50%). Mean arterial pressure remained stable along with mean heart rate change of -2.1 % (-20. 6 % to +11.4%). Four patients who were IV inotrope dependent were successfully transitioned off IV inotropes to oral agents. None of the patients had any significant atrial or ventricular arrhythmias during the ICU stay. Digoxin levels were consistently below 2 ng/ml at 72 hours post digoxin loading. Conclusions: We demonstrated the efficacy and safety of IV digoxin loading in acutely improving cardiac index and facilitating weaning off IV inotropes in the setting of low output decompensated HF.