Study Finds Incidence Of Heart Attack Increases Amid Decrease In Cardiovascular-Related Deaths

From 1987 to 1994, and consistent with a 30-year trend, the researchers observed significant annual decreases in mortality from coronary heart disease. There was, however, a stable or slightly increasing incidence of first-time hospitalization for myocardial infarction, or heart attack. A report on the research appears in the Sept. 24 issue of the New England Journal of Medicine.

"After 30 years of remarkable progress against coronary heart disease, our data suggest that while the rate of mortality continues to improve, the rate at which heart attacks occur in the population may no longer be decreasing and, in fact, might be going up in some," said Dr. Wayne D. Rosamond, assistant professor of epidemiology at the UNC-CH School of Public Health and lead author of the report. "We expected to see a continued decline in new cases, but we did not." The decline in mortality among residents of the four geographically and ethnically diverse communities studied -- Forsyth County, N.C.; Jackson, Miss.; Washington County, Md.; and the suburbs of Minneapolis -- may be due largely to improvements in the treatment and secondary prevention of myocardial infarction, the researchers concluded.

The health community, Rosamond said, has done a tremendous job in getting the message out to the public about the need to exercise and eat right, quit smoking and control blood pressure as methods to prevent heart disease. But, he added, "We now need to get that prevention message to those who haven't gotten it yet."

Additionally, Rosamond said, "There may also be other factors that contribute to heart disease that we haven't addressed because we don't know about them yet."

The largest average annual decrease in mortality due to coronary heart disease occurred among white men (-4.7 percent), followed by white women (-4.5 percent), black women (-4.1 percent) and black men (-2.5 percent), the public health researchers found.

Overall, according to their findings, in-hospital mortality from coronary heart disease fell by 5.1 percent per year, whereas out-of-hospital mortality declined by 3.6 percent per year. There was no evidence of a decline in the incidence of hospitalization for a first myocardial infarction among either men or women; in fact, such hospital admissions increased by 7.4 percent per year among black women and 2.9 percent per year among black men. Rates of recurrent myocardial infarction decreased and survival after myocardial infarction improved.

In contrast to the flat trends in the rates of hospitalization for myocardial infarction, the annual rates of recurrent myocardial infarction showed a significant 18.8 percent decline among men (-2.6 percent per year) and a 14.5 percent decline among women (-1.9 percent per year.)

The researchers surveyed hospital admissions in the four communities, watching for myocardial infarction and in-hospital and out-of-hospital deaths due to coronary heart disease among 35- to 74-year-old residents. An estimated 11,869 hospitalizations for myocardial infarction and 3,407 fatal coronary events occurred between 1987 and 1994.

Mortality due to coronary heart disease -- across the four communities -- declined 28 percent for men and 31 percent for women over the eight-year period. The decline was evident among both blacks and whites.

Among men, 64 percent of all deaths due to coronary heart disease occurred outside the hospital, with essentially no change in this percentage between 1987 and 1994. About half of the deaths among women during this period occurred out-of-hospital, except in 1988 and 1994, when this proportion was about a third.

"The data show consistently over a period of years that the majority of people dying from heart attack do so before they reach a hospital," Rosamond said. "To see progress in that piece of the pie, we need to further focus on prevention." In addition to Rosamond, authors include Drs. Lloyd E. Chambless, Limin Clegg and Chin-Hua Wang, all of the UNC-CH School of Public Health's department of biostatistics; Dr. Aaron R. Folsom of the University of Minnesota in Minneapolis; Dr. Lawton S. Cooper of the National Heart, Lung and Blood Institute in Bethesda, Md.; Dr. David E. Conwill of the University of Mississippi Medical Center in Jackson; and Dr. Gerardo Heiss, also of the UNC-CH epidemiology department.

Besides UNC-CH, the following institutions also participated in the study: Wake Forest University in Winston-Salem; University of Mississippi Medical Center in Jackson; University of Minnesota in Minneapolis; and Johns Hopkins University in Baltimore.