Colonel Meow -- Death Caused by Heart Cat-astrophy

Internet sensation Colonel Meow died of CARDIAC ARREST ... triggered while valiantly trying to fight off a kidney infection ... TMZ has learned.

The Colonel's owner Anne Marie Avery tells us ... Meow was rushed to a hospital last week after he started breathing heavily -- and docs quickly realized his kidneys were failing because of an infection.

Colonel fought like cats and dogs for a week ... but stress eventually got the best of him.

Avery plans to create a charity in the Colonel's honor -- and she's already got the support of Grumpy Cat and Keyboard Cat.