Category: Federal Forum Posters
Purpose: Digoxin should not be used as monotherapy for rate control in atrial fibrillation (AFib), and digoxin should only be used in heart failure with reduced ejection fraction (HFrEF) patients who remain symptomatic after treatment with appropriate guideline directed medical therapy (GDT). Also, digoxin laboratory monitoring should occur at least annually in patients receiving digoxin therapy. Retrospective clinical trials have provided evidence of increased mortality with digoxin use. The primary objective of this MUE was to evaluate prescribing practices of digoxin in veterans with AFib and/or congestive heart failure (CHF). A secondary objective was to evaluate appropriateness of digoxin monitoring.
Methods: This MUE was approved by the Pharmacy and Therapeutics (P&T) Committee prior to implementation. A patient list was generated from Microsoft SQL on October 23, 2017 that included all veterans in the healthcare system with a digoxin prescription issued between October 23, 2016 and October 22, 2017. Patients were distributed for retrospective chart reviews to pharmacists within the healthcare system. Patient charts were accessed through the Computerized Patient Record System (CPRS). Veterans were excluded upon chart review if determined to not be taking digoxin. The following data were collected: age, sex, heart failure diagnosis, AFib/atrial flutter diagnosis, digoxin prescription information, concomitant heart failure medications, concomitant AFib medications, and lab monitoring information.
Results: The MUE included a review of 98 veterans. Eight veterans were excluded due to inactive digoxin therapy. The majority of veterans (75.5 percent) were receiving digoxin for management of AFib. Digoxin was found to be prescribed as monotherapy for AFib rate control in 7 patients (7.7 percent). A total of 29 patients (32.2 percent) had HFrEF. Appropriate GDT was missing in 12 patients (41.4 percent) of patients with HFrEF. Only 2 patients (0.22 percent) had a diagnosis of heart failure with preserved ejection fraction without a diagnosis of AFib. Digoxin use was deemed appropriate based on clinical judgement of pharmacists performing chart reviews in 73 patients (75.5 percent). The majority of veterans had a serum creatinine (Scr), potassium (K), and magnesium (Mg) drawn within the past year. However, only 37 patients (41.1 percent) had a digoxin trough drawn in the past year. Digoxin monitoring was deemed appropriate (based on at least annual monitoring of Scr, K, MG, and digoxin trough) in only 25 patients (27.8 percent).
Conclusion: Patients with HFrEF may benefit from the addition of an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin II receptor blocker (ARB) in addition to an evidence based beta blocker. Patients with an ejection fraction less than 35 percent should also be considered for aldosterone antagonist therapy. The greatest area for improvement regarding digoxin therapy within this healthcare system involves increasing the monitoring frequency of digoxin troughs to at least annually. Results of this MUE were presented to the P&T committee, and recommendations for optimizing digoxin use and laboratory monitoring were provided to prescribers via notes entered into patient’s charts.
Christopher Wilson– Pharmacy Resident, Sheridan VA Medical Center, Sheridan, WY