heartattack 3Nearly half of all heart attacks may be silent and like those that cause chest pain or other warning signs, silent heart attacks increase the risk of dying from heart disease and other causes, according to new research in the American Heart Association’s journal Circulation.Researchers analyzed the records of 9,498 middle-age adults already enrolled in the Atherosclerosis Risk in Communities (ARIC), a study analyzing the causes and outcomes of atherosclerosis – hardening of the arteries. Researchers examined heart attack differences between blacks and whites as well as men and women. Over an average of nine years after the start of the study, 317 participants had silent heart attacks while 386 had heart attacks with clinical symptoms. Researchers continued to follow participants for more than two decades to track deaths from heart attack and other diseases.

They found that silent heart attacks:

made up 45 percent of all heart attacks;
increased the chances of dying from heart disease by 3 times;
increased the chances of dying from all causes by 34 percent; and
were more common in men but more likely to cause death in women.
“Women with a silent heart attack appear to fare worse than men,” Soliman said. “Our study also suggests that blacks may fare worse than whites, but the number of blacks may have been too small to say that with certainty.”

Researchers accounted for many factors that could bias results, including smoking, body weight, diabetes, high blood pressure and cholesterol. They did not adjust for access to care but did adjust for income and education, which could impact access to care.
Symptoms of silent heart attacks appear so mild that they are barely noticed, if at all. They are detected later, usually when patients undergo an electrocardiogram, better known as an ECG or EKG, to check their heart’s electrical activity, researchers said.
Soliman said that silent heart attacks, once discovered, should be treated as aggressively as heart attacks with symptoms.
“The modifiable risk factors are the same for both kinds of heart attacks,” he said. “Doctors need to help patients who have had a silent heart attack quit smoking, reduce their weight, control cholesterol and blood pressure and get more exercise.”
In 1987, the ARIC Study began enrolling participants who were free of heart disease in four U.S. communities in Maryland, Minnesota, Mississippi and North Carolina to determine the risk factors for heart disease and health effects of hardening of the arteries over time.

Sources: American Heart Association, The Norwegian University of Science and Technology (NTNU)

Full bibliographic information:
Race and Sex Differences in the Incidence and Prognostic Significance of Silent Myocardial Infarction in the Atherosclerosis Risk in Communities