Buffy the Vampire Slayer star Nicholas Brendon ’s cause of death has been shared. The actor died aged 54 on 20 March , with his family saying he “passed in his sleep of natural causes”. According to a death certificate obtained by Page Six , Brendon died from heart disease caused by blocked arteries and high blood pressure, and he also had pneumonia. A previous heart attack suffered by Brendon was also listed as a contributing factor. Nicholas Brendon had been open about his previous health issues (Getty) “Autopsy demonstrated an adult male with a markedly enlarged heart, severe stenosis of the right coronary artery, moderate stenosis of the left anterior descending and left circumflex arteries, acute pneumonia, and inflammation of the small bowel,” Putnam County Coroner Todd Zeiner wrote in the report. “The small bowel inflammation is most likely secondary to ischemic changes related to the cardiogenic shock.” Brendon has been open about his previous health issues .…