New details are coming out about Patrick Muldoon's death. As we previously reported, the Days of Our Lives alum died at 57 on April 19. His sister, Shana Muldoon-Zappa, told TMZ he suffered a heart attack. Now, less than two weeks after his untimely passing, we are learning more about his cause of death. Related: Patrick's Sister Reveals His Last Video - Taken Just Days Before His Death According to a death certificate obtained by Us Weekly on Wednesday, Patrick's immediate cause of death was a myocardial infarction, also known as a heart attack.