<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by Heart Attack ? [/INST] Very common. Each year, more than 1 million people in the U.S. have a heart attack and about half of them die. About one-half of those who die do so within 1 hour of the start of symptoms and before reaching the hospital. </s>