redundant first sentence
A '''heart attack'''
is when a clot form in a major artery blocking [[blood]] flow. A heart attack occurs when blood flow to a section of heart muscle becomes blocked. If the flow of blood isn’t restored quickly, the section of heart muscle becomes damaged from lack of oxygen and begins to die.
Heart attack is a leading killer of both men and women in the United States. But fortunately, today there are excellent treatments for heart attack that can save lives and prevent disabilities. Treatment is most effective when started within 1 hour of the beginning of symptoms. If you think you or someone you’re with is having a heart attack, call 9–1–1 right away.