Noninvasive testing using SPECT, PET or coronary CTA
played only a small role in physicians’ decisions to refer patients at
high risk for coronary artery disease to cardiac catheterization or alter their
medications, according to study data from SPARC.
Researchers enrolled 1,703 patients with an intermediate
to high risk for CAD without a history of CAD undergoing
SPECT, PET or coronary CTA. Ninety day post-test rates of
catheterization and medication changes were assessed.
At 90 days, 9.6% of patients underwent catheterization
after noninvasive imaging: 2.8% with normal/nonobstructive results, 20.3% with
mildly abnormal and 48.2% with moderately to severely abnormal study results
(P<.001). Among patients who underwent SPECT, 4.3% were referred to
catheterization vs. 11.1% after PET and 13.2% after coronary CTA
(P<.001). Study results showed that, of patients referred for
catheterization, 62.6% had evidence of obstructive CAD. Multivessel CAD was
found in 30% of SPECT, 49% of PET and 27% of CTA of patients with moderately to
severely abnormal findings. Zero percent of SPECT, 12% of PET and 24% of CTA of
mildly abnormal findings showed multivessel CAD.
Medication use at baseline was infrequent, according to
study results. Researchers found a greater change in aspirin and lipid-lowering
agent use after CTA vs. SPECT or PET in a risk-adjusted analysis.
Lipid-lowering agent use was higher in patients referred for PET (52.6%) and
coronary CTA (50%). Overall, 24% of patients were taking aspirin, beta-blockers
and lipid-lowering agents, 32% were taking two of these medications, 29% were
taking one and 16% were taking none. Study results showed an increase in all
three medications from baseline to 90 days in almost all imaging modality
Researchers found an increase in catheterization and
medication rates that correlated with abnormality of test findings. Ninety days
after the index test, 38% to 61% of patients with severe test results were not
referred to catheterization, 20% to 30% were not receiving aspirin, 35% to 44%
were not receiving a beta-blocker and 20% to 25% were not receiving a
lipid-lowering agent. According to study results, 59.8% of patients did not
receive referral for catheterization or medication changes, 6.1% received
catheterization or medication changes, 3.5% received catheterization referral
only and 30.1% received medication changes only.
Although many physicians try to justify the use of CV
imaging tests as playing a central role in patient management, this noninvasive
study showed CV imaging plays only a modest result on clinical management of
patients referred for clinical testing.
“The assumed paradigm is that in the setting of
abnormal study results — particularly high-risk results — patients
undergo intervention,” the researchers wrote. “The relatively limited
changes in management after abnormal study results, especially high-risk
findings, undermine this paradigm, especially because in our diagnostic cohort,
these abnormalities represented a de novo CAD diagnosis.”
Disclosure: See the study for a full list of