If digoxin had been controlling previously unrecognized heart failure, what could happen after it is stopped while metoprolol is continued?

Stopping digoxin while keeping metoprolol can unmask the heart failure that digoxin was silently controlling, and metoprolol may blunt the warning signs.

The evidence from the PROVED and RADIANCE trials is clear: when digoxin was withdrawn from stable heart failure patients on background therapy (including diuretics and ACE inhibitors), the withdrawal group had a significantly higher rate of worsening heart failure [2]. In the PROVED trial, digoxin withdrawal led to more decompensation even though patients were on diuretics [2]. The RADIANCE trial showed the same pattern in patients on triple therapy including ACE inhibitors [2]. These were not frail patients on the edge. They were stable enough to be randomized to withdrawal.

Now add metoprolol to the picture. Metoprolol lowers heart rate and reduces cardiac contractility. In heart failure, beta-blockers are life-saving long-term, but they can initially worsen symptoms because the heart relies on sympathetic drive to maintain output. If digoxin was providing inotropic support that kept the patient compensated, removing it while the beta-blocker continues means the heart loses one of its supports while the other is actively restraining it. The patient may not develop a racing pulse or palpitations as a warning sign, because metoprolol suppresses those. Instead, the first sign could be fatigue, fluid retention, or sudden decompensation.

The 2014 systematic review on medication withdrawal in stable heart failure found that stopping RAAS inhibitors and beta-blockers increased hospitalizations [1]. That review did not cover digoxin withdrawal specifically, but it reinforces the principle: removing a drug that was working in a compensated patient is risky, and the risk is higher when the remaining drugs blunt the compensatory mechanisms.

The DIG trial showed that digoxin reduces heart failure hospitalizations without a clear mortality benefit [2]. That means for the patient who was on digoxin and stable, the drug was likely preventing hospitalizations. Stopping it reverses that protection. The economic analysis from 1995 estimated that continuing digoxin saved $406 million annually by preventing 137,000 hospital admissions and 27,000 emergency visits [3]. Those numbers are old but the mechanism has not changed.

My call: stopping digoxin while continuing metoprolol in a patient whose heart failure was previously unrecognized and controlled by digoxin carries a real risk of decompensation, and the beta-blocker may mask the early warning signs. The safer path is to get a baseline ECG and digoxin level, then consider a slow taper under monitoring, not an abrupt stop. Confidence: moderate, because the evidence on this exact combination (digoxin withdrawal with concurrent beta-blocker) is not directly tested in the retrieved studies, but the mechanism and the withdrawal trial data point in the same direction.