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ACC – Amanda Jekowsky: (202) 375-6645,
ajekowsk@acc.org
November
2, 2009
Combining Calcium Scoring and SPECT Imaging Gives More Accurate
Read on Patients’ Short- and Long-Term Heart Risk
Approach helps identify patients earlier in disease
process and tailor therapy
By relying solely on a patient’s clinical risk profile
or the results of one imaging test when assessing patients
with chest pain, physicians may be missing important, early
signs of atherosclerotic disease and opportunities to intervene,
according to new findings published in the November 10, 2009,
issue of the Journal of the American College of Cardiology
(JACC). The authors recommend adding coronary artery
calcium score (CACS) testing in patients with a normal single-photon
emission computed tomography (SPECT) scan to better identify
those at high long-term risk for cardiac events, in whom an
earlier focus on aggressive risk factor modification and other
medical therapies may be beneficial.
“Typically, when a patient presents with chest pain
and the [SPECT] test result is normal, we tell them everything
looks fine, but this may not be the case,” says John
Mahmarian, M.D., a cardiologist in Houston, TX, and principal
investigator of the study. “If a large extent of calcium
is present in the coronary arteries, which can’t be
measured by functional SPECT imaging, he or she is at high
long-term risk for a cardiac event. Based on our findings,
using both tests to define risk is better than either test
alone.”
The study—the first to be conducted over such a long
duration—found that approximately half of all patients
with a normal SPECT result had a CACS of at least moderate
severity, signaling cardiac risk that would not otherwise
have been predicted. Increasing CACS severity is associated
with a greater likelihood of cardiac events and deaths. Alarmingly,
the risk of death or a heart attack over time increased by
3-fold when the calcium score was severe in patients with
a normal SPECT. CACS was also found to be a stronger predictor
of cardiac events than diabetes, which is considered synonymous
with having coronary artery disease.
For this reason, authors urge CACS be performed in patients
with a normal SPECT who have an intermediate or high clinical
risk factor profile for coronary artery disease (e.g., smoking,
high cholesterol, high blood pressure, diabetes, family history).
If CACS is high, patients should be treated aggressively to
prevent the progression of disease, adds Dr. Mahmarian.
“Although a normal SPECT result predicts excellent
short-term event-free survival, it doesn’t tell us anything
about long-term risk, and long-term outcome is significantly
worse if the CACS is severe,” said Dr. Mahmarian. “By
integrating these two tests, we can identify patients at high
long-term risk for heart problems and may, thereby, have a
better shot at preventing further development of obstructive
disease and improving outcomes.”
Investigators followed 1,126 asymptomatic patients without
a previous history of coronary artery disease who had a CACS
and stress SPECT scan performed within a close period of time
(median of 56 days). The study period was from December 1995
to May 2006.
“Our results reinforce the need to press forward and
look at how an integrated approach to imaging can be cost-effective
in preventing downstream events and improving outcomes,”
said Dr. Mahmarian.
The authors say the next step is to conduct prospective trials
to evaluate how adding CACS to functional SPECT scans can
guide the intensity of therapy targeted to individual patients
and whether such an approach can improve outcome in a cost-effective
manner.
Dr. Mahmarian reports no conflicts of interest.
Additional Background
A functional SPECT test is used to assess how blood flows
to the heart. A normal SPECT result generally defines a group
with a <1% annual risk of cardiac death and/or nonfatal
heart attack, which increases to approximately 6% if the study
result is abnormal.
CACS can detect varying degrees of blockages in the heart
before the development of stress-induced myocardial ischemia,
a painful heart condition caused by lack of blood flow to
the heart.
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About the ACC:
The American College of Cardiology is leading the way to optimal
cardiovascular care and disease prevention. The College is
a 37,000-member nonprofit medical society and bestows the
credential Fellow of the American College of Cardiology upon
physicians who meet its stringent qualifications. The College
is a leader in the formulation of health policy, standards
and guidelines, and is a staunch supporter of cardiovascular
research. The ACC provides professional education and operates
national registries for the measurement and improvement of
quality care. More information about the association is available
online at www.acc.org .
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