The increased odds weren't huge, although multiple job losses posed as big a threat as smoking, high blood pressure and other conditions that are bad for the heart.

The researchers analyzed data on more than 13,000 men and women aged 51 to 75 taking part in an ongoing health and retirement survey partly sponsored by the National Institute on Aging. Since 1992, participants have been interviewed every two years about their employment and health.

The new analysis has several limitations. The data show periods of unemployment but don't indicate whether people were fired, laid off, out of work while switching jobs, or had voluntarily left a job. The researchers considered all of these situations "job losses," but it's likely the greatest risks for heart attacks were from being fired or laid off, said researcher Matthew Dupre, an assistant professor at Duke University and the lead author. Retirement was not considered unemployment