Should we still prescribe digoxin in mild-to-moderate heart failure? Is quality of life the issue rather than quantity?

The recently reported Digitalis Investigation Group (DIG) study has shown that digoxin has no demonstrable effect on survival in heart failure, but may be useful to ameliorate morbidity. The question may be raised whether digoxin is useful for symptomatic improvement in patients with mild or moderate heart failure. A major difficulty in answering this question is the lack of appropriate clinical measures of heart failure that allow a categorization such as mild, moderate and severe heart failure. However, data in several clinical trials permit an approach to this issue in an approximate way. For instance, the DIG study itself indicated that the beneficial clinical effect of digoxin was also apparent in pre-defined subgroups which corresponded to less severe forms of heart failure. The problem with the DIG study in this respect was the lack of direct measures of clinical improvement and the use of what might be taken as surrogates for these; however, it can probably be assumed that digoxin had a beneficial symptomatic effect even in patients with milder forms of heart failure. Direct clinical measures of clinical result were used in the Randomized Assessment of the effect of Digoxin on Inhibitors of ACE Study and the Prospective Randomized Study on Ventricular Failure and the Efficacy of Digoxin. Some inconsistencies between the clinical results of these trials may be explained partly on the basis of sample size, although on the whole the results point to a definite clinical improvement of patients on digoxin therapy, even when heart failure was considered to be mild on the basis of several measurements. Admittedly, the size of the effect of digoxin therapy in these patients may be quite modest. Although some concerns over safety may remain after the DIG trial, it can generally be accepted that digoxin is an effective drug for symptomatic improvement in patients with mild or moderate heart failure. The small size of this effect, however, indicates that the decision to use the drug may well be left to the discretion of the attending physician.