Appropriateness of digoxin use in medical outpatients

Digoxin is the third most commonly prescribed drug, yet limited information exists about its use in outpatients. Therefore, 242 medical outpatients receiving digoxin at our hospital were studied to evaluate the appropriateness of its use, defined by: (1) current or past supraventricular arrhythmias and/or (2) left ventricular systolic dysfunction (ejection fraction less than 45 percent).

Charts of 242 patients receiving digoxin were obtained. The patients were divided into groups based upon their physician's stated indication for digoxin therapy. Patients with only a clinical diagnosis of congestive heart failure (CHF) underwent echocardiography or radionuclide angiography to quantify left ventricular systolic function. Those with documented supraventricular arrhythmias and/or those with confirmed left ventricular systolic dysfunction were classified as appropriate candidates for digoxin.

Ninety-five percent of patients received digoxin for appropriate indications; 75 percent had confirmed supraventricular arrhythmias (27 percent also had CHF) and 20 percent with normal sinus rhythm had documented systolic dysfunction. However, physicians had difficulty in the clinical assessment of left ventricular function; 18 percent of patients with sinus rhythm and CHF by the Framingham scoring system and 20 percent of those with supraventricular arrhythmias and CHF had preserved systolic function. An S3 was present in 15 percent of patients with preserved ejection fraction and CHF and in 69 percent with low ejection fraction; hypertension was significantly more common in the former group. Noninvasive assessment of systolic function was obtained in 97 percent of patients independent of this study, yet some patients without supraventricular arrhythmias and with documented preservation of systolic function continued to receive the drug.

Noninvasive assessment of left ventricular function, which appears to have become routine, is of value in the appropriate utilization of digoxin, since clinicians' assessment of left ventricular function may be inaccurate. Physicians also do not always discontinue digoxin therapy when indicated.