Frequency of ‘Silent’ Heart Attacks

Undiagnosed, or "silent," heart attacks affect nearly 200,000 people in the United States annually. As many as 40 to 60 percent of all heart attacks are unrecognized according to a new study from Duke University Medical Center. Even if a heart attack occurred in the distant past, it may still leave a signature called a Q-wave on an electrocardiogram. But there are silent heart attacks that do not have associated Q-waves.

By definition, a heart attack usually occurs when a clot obstructs blood flow from a coronary artery to the heart. This may cause severe chest pain, shortness of breath, fainting and nausea. But sometimes a heart attack is not painful, or the person experiencing it does not recognize the symptoms as heart-related, so he or she does not go to a hospital for treatment. Cardiologists have only recently become attuned to the prevalence of these silent heart attacks, and research on treatment is limited. The risk factors for silent heart attacks are the same as for regular heart attacks, experts say, and include smoking, diabetes, stress and family history.

Researchers at Duke University Medical Center used a relatively new technique called delayed-enhancement cardiovascular magnetic resonance and then followed up with patients after about two years. The study was done on 185 patients who had never had a diagnosed heart attack but were suspected of having coronary artery disease. The researchers found that 35 percent of patients had evidence of a heart attack and that silent heart attacks without Q-waves were three times more common than those that had Q-waves. Patients with non-Q-wave silent heart attacks also had 11 times higher risk of death from any cause and a 17-fold risk of death from heart problems compared with patients without any heart damage.

Dr. Han Kim, a cardiologist at Duke University and lead author of the study said "If you don't know when an actual event occurred, it becomes difficult to prescribe therapy." Treatment for someone who has had a silent heart attack is usually the same for someone who came to the hospital immediately after a heart attack, Kim said. This may include beta blockers, statin drugs, aspirin or other medications.

Researchers noted that patients with non-Q-wave silent heart attacks were also generally older and were more likely to have diabetes. There needs to be more of a focus on prevention among these risk groups, said Dr. David Wiener, a cardiologist at the Thomas Jefferson University Hospital in Philadelphia, Pennsylvania, who was not involved in the study

Once again these studies underscore the importance of identifying those with the disease, stratifying their risk and beginning interventions designed to reduce the rate of development of atherosclerosis as soon as possible. statin and micronutrient therapies have proved to be effective when managed under the care of a physician. EBT remains the earliest modality for the detection and quantification of coronary calcium available anywhere.

J.A. Rumberger, M.D. FACC

Medical Director, PrevaHealth