What does the flu have to do with the heart?

For some people, the effects of the influenza (flu) virus can lead to a heart attack or cardiac arrest (sudden death). These people typically have reduced blood flow to the heart due to atherosclerosis (narrowed arteries). Because the flu can cause blood oxygen levels to drop to dangerously low levels, it can further reduce the supply of oxygen to the heart, causing a heart attack or cardiac arrest. Fortunately, getting an annual flu shot is associated with reduced risks of a heart attack and related cardiac events.