UA/MI simple question

1) Is it possible that a patient is diagnosed with unstable angina, but not MI, even if he is unconscious or needs intubation ?
Sure why not, but typically some form of history is needed to illicit symptoms

2) Is it possible that a patient is diagnosed with myocardial infarction but Cardiac enzymes were normal ?
Yes, ST elevation on ECG with chest pain can present in the first hours with a normal trop, that's why we get a second one.

3) Is 'increase of cardiac enzymes' the only difference between Unstable angina and NSTEMI ?
Pretty much, clinically speaking, think of the pathophysiology as well...