While the overall risk of sudden cardiac death following MI has declined significantly in the past 30 years, there is an increased risk for the first month after having an MI. The risk after 30 days decreases unless patients develop heart failure, according to a study in the Nov. 5 issue of Journal of the American Medical Association.
Determining which patients are at risk for sudden cardiac death following MI remains challenging, the authors wrote. Currently, risk prediction approaches are based on characteristics assessed shortly after MI—a strategy that may be insufficient. Other factors that occur in the days to weeks following an MI, such as heart failure or recurrent ischemia, may be associated with risk of sudden cardiac death.
A. Selcuk Adabag, MD, of Veterans Affairs Medical Center in Minneapolis, and colleagues at the Mayo Clinic in Rochester, Minn., studied 2,997 residents (average age 67, 59 percent men) who had a heart attack in Olmsted County, Minn., between 1979 and 2005. Patients were followed through medical records for a median of 4.7 years, through Feb. 29 of this year.
During this time, 1,160 patients died, including 24 percent from sudden cardiac death. The researchers reported the 30-day cumulative incidence of sudden cardiac death was 1.2 percent, which is four times higher than expected. For each following year, however, the rate of sudden cardiac death was constant at 1.2 percent per year—lower than the rate among the general population. The cumulative five-year incidence of sudden cardiac death among MI patients was 6.9 percent.
“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,” the authors concluded. “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. This underscores the importance of continued surveillance of patients after myocardial infarction and the dynamic nature of risk stratification.”