Heart attack patients are more susceptible to die within the first 30 days after the attack, a study in the November 5 issue of The Journal of the American Medical Association says.

Researchers from the Veterans Affairs Medical Center and Mayo Clinic in Minnesota studied 2,997 residents who survived a heart attack in Olmsted County, Minn., between 1979 and 2005. The patients were on average 67 years old and 59 percent of them were men.

The researchers followed them through their medical records until the time of their death or through the final follow-up in February 2008.

During the follow-up period, 1,160 patients died, including 282 (24 percent) from sudden cardiac death, which is a “devastating complication of myocardial infarction [heart attack],” the authors wrote.

The 30-day rate of sudden cardiac death was 1.2 percent after which the rate remained constant at 1.2 percent per year, Veronique Roger, M.D., M.P.H., of the Mayo Clinic, and colleagues found.

When comparing the finding with the general population, heart attack patients had a 4.18-fold increased risk of sudden cardiac death for the first 30 days, but a significantly lower risk after that.

“In the community, the risk of sudden cardiac death is the highest during the first month after myocardial infarction when it markedly exceeds the rate in the general population. Among 30-day survivors, the risk of sudden cardiac death declines rapidly but it is markedly increased by the occurrence of heart failure during follow-up,” the authors conclude.

That’s why the authors underlined the importance of continued surveillance in heart attack patients.

The study was funded by a grant from the Public Health Service and grants from the National Institutes of Health.