It has generally been thought that sudden cardiac arrest strikes without warning. But new research concludes that for many men, there are numerous, unheeded red flags.

The Oregon Sudden Unexpected Death Study looked at 567 men who suffered cardiac arrest. About 53 percent had symptoms between four weeks and one hour before the attack. The most common symptom was chest pain, followed by shortness of breath and dizziness, fainting or palpitations. Researchers said their findings were especially important because fewer than 10 percent of those who suffer cardiac arrest outside a hospital survive.

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The research was presented at the American Heart Association's Scientific Sessions last month. The heart association says more than 350,000 out-of-hospital cardiac arrests occur in the United States each year.

Researchers said they are conducting a similar study with women.