Objectives. We investigated whether patients with mild heart failure due to left ventricular systolic dysfunction were at risk of worsening during digoxin withdrawal. Background. Deterioration during digoxin withdrawal is often believed to be restricted to patients with moderate to severe clinical evidence of heart failure. To test this hypothesis, we studied the outcome of patients categorized by treatment assignment and a clinical signs and symptoms heart failure score in two rigorously designed clinical heart failure trials: the Prospective Randomized Study of Ventricular FunctiOn and Efficacy of Digoxin (PROVED) and the Randomized Assessment of Digoxin and Inhibitors of Angiotensin-Converting Enzyme (RADIANCE) trial. Methods. Potential differences in treatment failure, left ventricular ejection fraction and exercise capacity were evaluated in three groups of patients: those with mild heart failure (score ≤2) who were withdrawn from digoxin (Dig WD Mild); those with moderate heart failure (score >2) who were withdrawn from digoxin (Dig WD Moderate); and patients who continued receiving digoxin regardless of heart failure score (Dig Cont). Results. Heart failure score at randomization did not predict outcome during follow- up in Dig Cont-group patients. Dig WD Mild-group patients were at increased risk of treatment failure and had deterioration of exercise capacity and left ventricular ejection fraction compared with that in Dig Cont-group patients (all p < 0.01). Patients in the Dig WD Moderate group were significantly more likely to experience treatment failure than patients in either the Dig WD Mild or Dig Cont group (both p < 0.05). Conclusions. Patients with systolic left ventricular dysfunction were at risk of clinical deterioration after digoxin withdrawal despite mild clinical evidence of congestive heart failure.
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