Imaging had only moderate impact on clinical management of patients referred for testing

Hachamovitch R. J Am Coll Cardiol. 2012;59:462-474.

Issue: March 2012

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 subgroups.

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 disclosures.

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