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Obviously, breathlessness is not due to heart failure
It is due to lung fibrosis
Fibrosis is from amiodarone
It may not be reversible at this stage. Reducing the dose may not help - it is not always dose related / the arrhythmia
may worsen and need a change of drug and so on.
Pulmonologist could offer some help - management for the present / prevention of progression...
For what it is worth, it sounds sensible to give the benefit of doubt and admit him in multi-speciality tertiary care super-speciality hospital - Dukes is a reputed institution. If they conclude nothing much can be done - at least we are convinced, satisfied that the best has been done for him.
Wishing speedy recovery