Tuesday, 18 May 2010 17:12
Including a coronary artery calcium score in a risk assessment for future heart disease events, such as heart attacks, provides a better estimate in some populations than a standard coronary risk factors assessment, according to research published in a recent issue of the Journal of the American Medical Association (JAMA) and supported by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health.
The findings were based on data from a study co-authored by Alan D. Guerci, M.D., president and CEO of St. Francis Hospital, The Heart Center.
A coronary artery calcium score was most helpful for people considered to be at intermediate risk of a heart disease – defined as those with a 3 to 10 percent chance of developing heart disease over the next five years – according to the report in the April 28 issue of JAMA.
In the Multi-Ethnic Study of Atherosclerosis (MESA), researchers used cardiac CT scans, which detect specks of calcium in the walls of the coronary arteries. These specks, indicating calcifications, are an early sign of coronary artery disease. Coronary artery disease is the cause of angina (exertional chest pain) and heart attacks, and it kills about 25 percent of Americans every year.
“This latest study reinforces the message that if you are at intermediate risk of cardiac disease based on the standard measures, your risk can be better assessed if you also have a calcium score,” says Dr. Guerci. “Based on results of this test, doctors can better determine appropriate treatment and the necessity of cholesterol-lowering medications.”
The study drew from 5,878 MESA participants, ages 45 to 84, who initially did not have known cardiovascular disease, and included both men and women who were white, African-American, Hispanic, or of Chinese heritage. Interviewers telephoned participants or a family member at intervals of nine to 12 months to inquire about interim hospital admissions, diagnoses of cardiovascular disease, and deaths.
Participants were followed for almost six years. Over the follow-up period, 209 participants experienced a heart disease event, such as heart attack, death from heart disease, or cardiac arrest. Using the coronary artery calcium score in addition to standard risk factors, a remarkable 55 percent of intermediate risk study participants were reclassified, with 39 percent reclassified into the low-risk category and 16 percent into the high risk category.
Risk classifications were created using risk factors from the Framingham Heart Study Risk Score and based upon the risk of having a heart attack or dying from coronary artery disease within five years. Risk factors considered were age, gender, tobacco use, systolic blood pressure (the top number in a blood pressure reading), blood pressure medication use, blood cholesterol levels, and ethnicity. Individuals with less than a 3 percent chance of heart disease in the next five years were considered to be low-risk; those with a 3 to 10 percent chance to be intermediate-risk; and those with more than a 10 percent chance to be high-risk.
The MESA findings indicate that a coronary artery calcium score may not be an efficient screening tool among low-risk individuals. In addition, it is generally accepted that patients who are at high risk should be treated regardless of their coronary artery calcium score, and as a result do not need coronary artery calcium testing for additional risk assessment.
Coronary artery calcium scanning has been a controversial screening test. Whether it would improve outcomes is unknown and the scans entail additional costs and some risks, such as exposure to small amounts of radiation.
MESA researchers are investigating the early stages of coronary artery disease in various studies. More than 6,000 ethnically diverse men and women from six communities in the United States are participating in MESA. Participants undergo coronary tests such as CT scans, magnetic resonance imaging, ultrasounds, and electrocardiograms.
Part of the National Institutes of Health, the National Heart, Lung, and Blood Institute (NHLBI) plans, conducts, and supports research related to the causes, prevention, diagnosis, and treatment of heart, blood vessel, lung, and blood diseases; and sleep disorders. The Institute also administers national health education campaigns on women and heart disease, healthy weight for children, and other topics. NHLBI press releases and other materials are available online at www.nhlbi.nih.gov.
The National Institutes of Health (NIH) — The Nation’s Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
St. Francis Hospital, The Heart Center is New York State’s only specialty designated cardiac center and is the busiest heart center in the Northeast. A recognized leader in the diagnosis, treatment and prevention of cardiac disease, St. Francis Hospital performs more cardiac surgery and interventional cardiac procedures than any other hospital in New York State. A leader in cardiovascular care for more than 50 years, St. Francis Hospital is a member of Catholic Health Services of Long Island (CHSLI). Contact 1.888.HEART.NY or visit www.stfrancisheartcenter.com.