What was the cause of Orville Wright's death?

Heart failure. I have heard that he was fixing the doorbell of his home when he collapsed and was taken to the hospital and died a short time later, on January 30, 1948-- and also that he collapsed at his office and was taken to the hospital. Both accounts have considerable detail, but clearly one of them is wrong. I have seen a copy of the death certificate though, and he did die of heart failure.