By Jonathan Springston, Associate Managing Editor, AHC Media

A surprising number of Americans may experience a heart attack but not know it because the episode does not produce classic symptoms, according to data from a recent study. These events are dubbed “silent heart attacks” and may prevent patients from recognizing a problem and receiving the care they need.

Researchers from the Wake Forest School of Medicine examined the records of more than 9,000 middle-age adults enrolled in the Atherosclerosis Risk in Communities (ARIC), a study analyzing the causes and outcomes of atherosclerosis. They explored 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 experienced silent heart attacks and 386 experienced heart attacks with clinical symptoms. Researchers followed study participants for more than two decades to track deaths from heart attack and other diseases.

Through this research, the authors found that silent heart attacks accounted for 45 percent of all heart attacks, increased the risk of dying from heart disease 3 percent, and by dying from all causes by 34 percent. The data also suggest silent heart attacks may lead to worse outcomes in female and black patients, though the authors noted the evidence is not quite adequate yet to draw definitive conclusions about the latter group.

In a silent heart attack, symptoms are so mild that patients barely notice them at all and only are detected later when patients undergo an ECG as part of routine medical care. The authors urged patients and medical practitioners to be mindful of symptoms and treat quickly.

“The modifiable risk factors are the same for both kinds of heart attacks,” Elsayed Z. Soliman, MD, MSc, MS, study senior author and director of the epidemiological cardiology research center at Wake Forest Baptist Medical Center, said in a statement. “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.”

For all the latest information about cardiology research, be sure to read Clinical Cardiology Alert. AHC Media also offers STEMI Watch: Diagnosis, Treatment, Complications, and Long-Term Management, a five-course online module designed to improve the consistency of cardiac care for STEMI (ST segment elevation myocardial infarction) patients.