[Digitalis therapy: prescription frequency, serum concentrations and withdrawal trials].

The frequency of therapy with digitalis glycosides was determined in 4.143 patients on their first visit at a medical outpatient clinic. 508 (12.3%) patients said to take digitalis. Of 480 (94.5%) patients, a digoxin serum concentration was obtained. It was in 229 (47.7%) patients below, in 31 (6.5%) above, and in 220 (45.8%) within the therapeutic range (0.8-2.0 ng/ml). From the 251 patients with a serum digoxin concentration greater than or equal to 0.8 ng/ml, 220 (87.7%) were not included in a withdrawal trial on the basis of predetermined criteria, mainly because of cardiac diseases (52%). Digitalis therapy was withdrawn in 31 patients. 5 patients started to take the drug again on their own; they were considered drop-outs. In the remaining 26 patients, no symptoms of heart failure appeared during a 3-month observation period; in 2 patients, however, atrial fibrillation requiring intervention occurred. Our results confirm the frequent use of digitalis therapy in Germany, but also the frequent presence of subtherapeutic serum digoxin concentrations. Withdrawal should be considered in patients with a questionable indication for this therapy; the occasional occurrence of supraventricular arrhythmias, and not so much of heart failure, should be anticipated.