CLEAN : North Korea claims Kim Jong-Nam died of heart attack

The transcript discusses a patient's medical history with a serious infection and hospitalization. It analyzes symptoms and test results, suggesting a heart attack as a cause. An incident is described where a victim died instantly after a substance was applied to their face. The investigation reveals how two other individuals survived the incident.

What does the text imply about the heart attack mentioned?

How did the victim die according to the text?