Plasma digoxin levels and ejection fraction in pediatric heart failure

Abstract

Background Digoxin has long been prescribed in children with heartfailure, but its efficacy has not been evaluated. A previous study atthe Department of Child Health, Dr. Cipto Mangunkusumo Hospitalrevealed that plasma digoxin levels, following a maintenance doseof 15 μg/kg/d, were sub-therapeutic. Regarding its narrow margin ofsafety, the trend is to use digoxin in even lower dose. Thus, the drug’simpact on cardiac performance need to be evaluated.Objective To evaluate whether a lower maintenance dose of digoxin(10 μg/kg/d) is sufficient to achieve a therapeutic level and to assess forpossible correlations between plasma digoxin level and left ventricularejection fraction (LVEF) as well as fractional shortening (LVFS).Methods A cross-sectional study was conducted on 20 pediatricheart failure patients at the Department of Child Health, Dr. CiptoMangunkusumo Hospital, Jakarta, from January to May 2012. Plasmadigoxin levels were measured by ELISA method after one month ormore of treatment; LVEF and LVFS were measured by echocardiography.Correlations between plasma digoxin level and LVEF or LVFSwere analyzed by Spearman’s correlation test. The LVEF before andafter digoxin treatment were compared by paired T-test.Results Thirteen out of 20 patients had plasma digoxinlevels within therapeutic range (0.5-1.5 ng/mL; 95%CI0.599 to 0.898) and 7 had sub-therapeutic levels (<0.5 ng/mL; 95%CI 0.252 to 0.417). No significant correlationswere observed between plasma digoxin level and LVEF(r=-0.085; P=0.722) or LVFS (r=-0.105; P=0.659). There was asignificant increase in LVEF before [42.18 (SD 14.15)%] and afterdigoxin treatment [57.52 (SD 11.09)%], (P < 0.0001).Conclusion Most patients in this study have plasma digoxin levelswithin therapeutic range. There are no significant correlationsbetween plasma digoxin level at the time point of measurementand LVEF or LVFS. However, an increase of LVEF is observed inevery individual patients following digoxin treatment.