A new study led by researchers at Wake Forest Baptist Medical Center in North Carolina and the University of Minnesota revealed that cardiac atrial fibrillation increases the risk of one specific type of heart attack. The study was published in the journal Circulation and is entitled “Atrial Fibrillation and Risk of ST-Segment Elevation versus Non-ST Segment Elevation Myocardial Infarction: The Atherosclerosis Risk in Communities (ARIC) Study.”
Atrial fibrillation is the most common type of heart rhythm disorder, characterized by an irregular and often abnormally fast heart rate. It occurs when the two upper chambers of the heart (the atria) contract very fast and irregularly reducing the heart’s efficiency and performance, causing a poor blood flow to the body. Some people with the disorder may have no symptoms, while others may experience shortness of breath, dizziness, heart palpitations, chest pain and weakness. Atrial fibrillation is estimated to affect approximately 6 million Americans and it has been reported to significantly increase the risk of stroke (or cerebrovascular accident) and heart attack (or myocardial infarction).
The mechanism behind the association of atrial fibrillation with heart attack is not clear, however. In this study, the link between atrial fibrillation and heart attack was assessed. Two specific types of heart attack were analyzed: the STEMI (ST-segment elevation myocardial infarction), a serious form that requires immediate medical intervention in which the coronary artery is completely blocked and a significant part of the heart muscle is unable to receive blood, and the NSTEMI (non-ST segment elevation myocardial infarction), a type of partial or temporary coronary artery blockade that does not induce a change in the ST segment elevation (a cardiac pattern) on the electrocardiogram and that causes less damage to the patient’s heart.
Researchers analyzed data from 14,462 individuals, mean age of 54 years, enrolled in the Atherosclerosis Risk in Communities (ARIC) study, a project developed between 1987 and 2010. Over a median follow-up period of 21.6 years, 1374 heart attack events were reported with 829 being NSTEMI, 249 STEMI and 296 unclassifiable.
The team found that atrial fibrillation increased the overall risk of heart attack by 63%, especially in women. Remarkably, researchers found that atrial fibrillation was only associated to one type of heart attack, the NSTEMI, which is the less severe and most common type of heart attack. This finding led the researchers to suggest that factors contributing to a partial blockage of the coronary arteries are probably establishing the link between atrial fibrillation and heart attack.
The research team concluded that atrial fibrillation increases the risk of NSTEMI heart attack. “These results have important implications for management of the risk of heart attack in people with atrial fibrillation,” said the study’s lead author Dr. Elsayed Z. Soliman in a news release. “For example, blood thinners that are commonly prescribed to people with atrial fibrillation to prevent stroke may not be as effective in preventing heart attacks in this population.”