Stunning new details surrounding Jim Irsay's death in May ... the legendary Indianapolis Colts owner reportedly passed away at the Beverly Hills Hotel while under the care of an addiction specialist.
The Washington Post obtained the death certificate for 65-year-old Irsay ... which listed his cause of death as cardiac arrest due to acute pneumonia, chronic atrial fibrillation and cardiac arrhythmia on May 21.
The document is signed by Dr.