Brendon died of atherosclerotic and hypertensive cardiovascular disease, leading to a 90-percent blockage of his right artery, coroners report states The cause of death for Buffy the Vampire Slayer ’s Nicholas Brendon has been revealed following the actor’s March 20 death at the age of 54. The Putnam County Coroner’s office announced Wednesday that Brendon died of atherosclerotic and hypertensive cardiovascular disease, with acute pneumonia and previous myocardial infarction as contributing factors, People reports . Brendon’s death was natural. According to coroner Todd Zeiner, the main cause of death was a 90 percent blockage in Brendon’s right coronary artery. Zeiner’s report states that, on the day of Brendon’s death, his friend Theresa called 911 to the actor’s home and “stated the decedent had been having a persistent cough and had been self-medicating with over-the-counter medications. He had been complaining about chest pain. She recommended a hospital, but he declined.…