Background: All guidelines agree that beta-blockers (BBs) should be used for patients with systolic heart failure (SHF) to improve survival. BBs are a class Ia indication for treatment of SHF based on 3 landmark clinical trials (CIBIS-II, COPERNICUS, and MERIT-HF). Despite recommendations, the doses of BBs prescribed are commonly less than target dose (TD). Underdosing of BBs is suggested by doses less than 50% of TD and/or sinus rate (SR) above 70 bpm whereas a very low dose of BB is 25% or less of the TD. Clinical and social factors including depression, dizziness, ability to walk without assistance, Morse Fall Scale score and living status, whether independently or in a care facility, could be likely reasons for patients receiving a very low dose of BB. Failure to achieve SR below 70 bpm might lead physicians to use ivabradine which is a relatively new and expensive medication and is a class IIa indication for SHF. The objective is to evaluate the clinical and social factors affecting underdosing of BBs between the two patient groups with ≤25% of TD vs >25% of TD.
Methods: A retrospective chart review was completed for SHF patients admitted to Charleston Area Medical Center from 2007 to 2016. Doses of BB, SR, and clinical/social factors were recorded. Patients over the age of 18 years with diagnosed SHF (EF<40%) and on BB treatment for more than 8 weeks prior to admission were included.
Results: An initial sample size of 254 patients with SHF was obtained. 65% (164 of 254) were on approved BBs. Of the patients on approved BBs, 71% (117 of 164) were receiving ≤ 25% of the TD and 29% (47 of 164) were receiving >25% of the TD. Mean SR on admission EKG was 85±19.5 in the ≤ 25% TD group, and 83±21.4 in the >25% TD group. Of the 164 patients on approved BB therapy, SR could only be recorded in 105 patients due to atrial pacing or atrial arrhythmias; and 82% (86 of 105) had a SR >70 bpm on their initial EKG. No statistically significant differences were identified between the two groups when reviewing the clinical and social factors.
Conclusions: This study will help enable cardiovascular clinicians to realize that although the use of BBs for SHF has improved dramatically since Get With The Guidelines; there is still marked underdosing of approved BB and inappropriate use of non-approved BB. We are unable to explain this practice based on the clinical and social factors that may have led to underdosing of BB. We found the mean dose of BBs to be 25% or less of TD in 71% (117 of 164) patients on approved BBs and only 18% (19 of 105) of these patients had SR <70bpm. Inappropriate dosing of BBs could potentially be responsible for worsening outcomes and possible overutilization of ivabradine.