What are you trying to find out? Cardiomyopathy has been a problem in a few
genetic lines of Birman cats but on the whole the breed has no particular
health problems associated with it. Apparently your cat was one of the
unfortunate few from a genetic line that carried certain defects.

Here is all I could find about the disease
http://circ.ahajournals.org/cgi/content/full/102/15/1863

and this quote from a Waltham symposium:
"Arrhythmogenic right ventricular cardiomyopathy (ARVC)

This form of cardiomyopathy has only recently been recognized in cats, and is
characterized by fibrofatty infiltration of the right ventricle, resulting in
marked right heart enlargement.9 Affected cats may be asymptomatic, may be
syncopal in association with arrhythmias, or may have right-sided heart
failure."

I take it your cat is showing signs of heart failure since you say he is dying.
However, this note does seem to indicate the condition is not necessarily
always fatal.

Good luck and I hope your cat can be treated in some way to prolong his life.