Please answer the following question: Article: Saturday, October 7th, was a marathon of sad tasks for Anna Politkovskaya. Two weeks earlier, her father, a retired official in the department of foreign affairs, had died of a heart attack as he _ from the Moscow Metro while on his way to visit Politkovskaya's mother, Raisa Mazepa, in the hospital. She had just been diagnosed with cancer and was too weak even to attend her husband's funeral. "Your father will forgive me, because he knows that I have always loved him," she told Anna and her sister, Elena Kudimova, the day he was buried. A week later, she had an operation and since then Anna and Elena had been taking turns helping her deal with her grief. Politkovskaya was supposed to spend the day at the hospital, but her twenty-six-year-old daughter, who was pregnant, had just moved into Politkovskaya's apartment, on Lesnaya Street, while her own place was being prepared for the baby. "Anna had so much on her mind," Elena Kudimova told me when we met in London, before Christmas. "And she was trying to finish her article." Politkovskaya was a special reporter for the small newspaperNovaya Gazeta, and, like most of her work, the piece focused on the terror that can be seen all over the southern republic of Chechnya. This time, she had been trying to report repeated cruel acts done by people faithful to the Prime Minister, Ramzan Kadyrov, who are in favour of Russia. In the past seven years, Politkovskaya had written dozens of accounts of life during wartime; many had been collected in her book "A Small Corner of Hell: reports from Chechnya." Politkovskaya was far more likely to spend time in a hospital than on a battlefield, and her writing bore frequent witness to robbery, and the uncontrolled cruelty of life in a place that few other Russians--and almost no other reporters--cared to think about. Question: Politkovskaya's father died of _ . Yes or no, is the answer "a disease"?
Answer:
Yes