hybrid imaging, a non-invasive modality that combines computed
tomography and nuclear stress testing can help predict adverse
cardiac events like heart
attack in patients being evaluated for coronary artery disease much
better, than using either of the techniques alone.
- Cardiac hybrid
imaging is an excellent long-term predictor of heart attack in patients
being checked for coronary artery disease
- Hybrid imaging uses
a combination of computed tomography (CT) and nuclear stress testing that detects
narrowing of the coronary artery and inadequate perfusion (ischemia) or
blood flow to the heart simultaneously
- Fusion imaging can
help determine whether coronary revascularization is needed or not.
The study was published in the journal Radiology
Coronary arteries carry
oxygen-rich blood away from the heart. When they become clogged with fatty plaque,
it leads to coronary artery disease (CAD).
plaque formation causes stenosis or
narrowing of the artery
‘Images recorded in a coronary CT angiography and myocardial perfusion technique can be combined to predict adverse cardiac events like heart attacks.’
CAD is a leading
cause of death and disability worldwide. The
condition is best diagnosed by invasive coronary angiography (ICA)
is considered the gold standard test
helps determine if the patient has the disease or not.
However, ICA does not
give any information on perfusion which
is important to predict a heart attack risk accurately. Perfusion
flow of blood into the heart muscle and inadequate
perfusion, also known as ischemia
, is a potential danger to the patient.
To measure the degree of stenosis (morphological
information) as well as myocardial perfusion (functional information) in a
single setting, a technique used nowadays is cardiac hybrid imaging.
Cardiac hybrid imaging consists of a combination (or
'fusion') of computed tomography
coronary angiography (CCTA)
perfusion imaging (MPI)
photon emission computed tomography, SPECT
, or positron emission tomography,
to diagnose CAD.
"In lesions with
less than 50 percent narrowing, one in five lesions still produce an
ischemia," said study co-author Philipp A. Kaufmann, M.D., professor and
chair of nuclear medicine, and director of cardiac imaging at University
Hospital Zurich in Switzerland.
Study Design and Results
So far, the cardiac
hybrid imaging approach has shown promise in studies that focus only on
short-term observations; the current research is the first one to find
information on long-term outcomes.
The research team analyzed data from 428
patients who underwent hybrid imaging for 6.8 years. The patients and
physicians were followed up through phone calls for endpoints known as hard
events; these included a nonfatal heart
attack (MI) and all-cause death, and a composite of major adverse cardiac
events that included MI, death, coronary revascularization and unstable angina
The data sets of SPECT and CCTA imaging were fused,
and the images were assigned to one of the following three categories: matched findings, unmatched findings, and
. Normal findings were normal CCTA findings or any
luminal narrowing less than 50 percent and no defect at SPECT.
- Patients with stenosis of 50 percent or more along with
visible ischemia in the area of the heart which was supplied blood by the
blocked vessel (matched findings), had more than five times the risk of adverse
events than those with normal findings.
- Patients with stenosis of 50 percent or more along with
visible ischemia that was not in the area of the heart fed by the blocked
artery (unmatched findings), had three times the risk of adverse cardiac
- During this follow-up period, there were 160 major
adverse cardiac events, including 45 deaths in
the final study population that comprised of 375 patients.
- The rates of the major
adverse cardiac events were 21.8 percent for matched findings and 9.0 percent
for unmatched, both groups considerably higher than the 2.4 percent rate for
show that cardiac hybrid imaging is an effective long-term predictor of adverse
cardiac events in patients evaluated for known or suspected coronary artery
. They could help guide whether or not a patient should have a
revascularization procedure such as bypass or angioplasty
with multiple lesions or complex coronary anatomy, it is, very difficult to
correctly identify the culprit lesion," said Dr. Kaufmann. "In a
previous multicenter trial, with hybrid imaging we were able to see that about
one in five patients should be revascularized in another coronary artery than
originally planned. The present study now documents the prognostic importance
of the comprehensive assessment provided by hybrid imaging."
The study supports
the use of CCTA for initial, non-invasive
evaluation of patients with known or suspected stable coronary artery disease
If the results appear normal, no additional imaging would be necessary. But, if
a lesion is evident, then clinicians could employ a nuclear scan
check the presence of ischemia and take
advantage of both modalities by fusing the results together to make a hybrid
"The strategy of
direct referral to invasive coronary angiography without non-invasive imaging
is obsolete," Dr. Kaufmann said. "Even after documenting coronary
artery disease with coronary CT angiography, we need further non-invasive
evaluation before deciding upon revascularization versus medication."
The researchers have plans of running a clinical trial to show
that hybrid imaging can have a positive impact on patient outcomes. They are
also planning to combine the CCTA/SPECT hybrid with information on coronary
artery shear stress (something they call "triple hybrid" imaging),
which could help identify lesions that as of now do not have an impact on
ischemia but will in the future.
- Aju P. Pazhenkottil, Dominik C. Benz, Christoph Gräni, Michael A. Madsen, Fran Mikulicic, Elia von Felten, Tobias A. Fuchs, Beatrice Hirt Moch, Julia Stehli, Thomas F. Lüscher, Oliver Gaemperli, Ronny R. Buechel, Philipp A. Kaufmann. Hybrid SPECT Perfusion Imaging and Coronary CT Angiography: Long-Term Prognostic Value for Cardiovascular Outcomes. Radiology, 2018
- Gaemperli O, Bengel FM, Kaufmann PA. Cardiac hybrid imaging. Eur Heart J. 2011 Sep