Who is at risk of sudden death in Australia from a heart attack? Sudden cardiac arrest (SCA) — or massive heart attack — as it is sometimes known, which kills an estimated 33,000 people in Australia alone each year, can strike anyone. Even a seemingly healthy person can suffer cardiac arrest without warning. According to the American Heart Association® (AHA), as many as 50% of SCA victims have no prior indication of heart disease — their first symptom is cardiac arrest.