LVAD = Left Ventricular Assist Device; usually used as a bridge to transplant when the heart is failing, rarely as destination therapy.

What do you mean by cutting his wire? If by that you mean you killed him, then I can't think of an instance in which you wouldn't be bad - perhaps not a bad person, but definitely doing a bad thing.

The only exception that I can see is if you were his doctor and he wanted the LVAD disconnected. Then it's OK (assuming that all the proper steps had been taken) - removing an intervention is ethically the same as not giving an intervention at all. No different than not doing CPR on someone who is DNR. Or if you were his surrogate decision maker and were acting with substitued judgement, i.e. doing what you thought HE would want (not what YOU would do). Though it would have been good to figure this out BEFORE the $200,000 LVAD was installed - that's a lot of money.

A little more clarity in the question would help me answer it better :).