There is considerable variability in the use of noninvasive cardiac imaging in patients with possible ischemia without an acute MI (AMI) among U.S. hospitals, a study published online Feb. 10 in JAMA Internal Medicine found.
In order to assess the variation among hospitals in their use of noninvasive cardiac imaging, Kyan C. Safavi, B.S., of the Yale University School of Medicine in New Haven, Conn., and colleagues used 2010 data from Premier, Inc., a healthcare improvement company, on patients with suspected ischemia who presented to an emergency department, an observation unit or an inpatient unit; received at least one cardiac biomarker test on day 0 or 1; and whose primary discharge diagnosis related to chest discomfort, a sign or symptom of ischemia; and/or coronary disease-related comorbidity. Patients with AMI were not included in the analysis.
The main outcomes were the number of patients who underwent noninvasive cardiac imaging to diagnose cardiac ischemia and the post-imaging rates of admission, coronary angiography and revascularization.
The investigators analyzed data involving 549,078 patients at 224 hospitals. The imaging rates ranged from 0.2 percent to 55.7 percent with a median of 19.8 percent. Broken down by quartile based on the proportion of patients who underwent noninvasive imaging for cardiac ischemia, rates for Q1 through Q4 were 6 percent, 15.9 percent, 23.5 percent and 34.8 percent.
They found that hospitals with higher imaging rates had higher admission rates (Q4, 40 percent; Q1, 32.1 percent) and higher angiography rates (Q4, 4.9 percent; Q1, 1.2 percent). Revascularization yield was lower for Q4 hospitals for noninvasive imaging compared with Q1 (5.4 percent vs. 7.6 percent) as well as for angiograms (8.8 percent vs. 41.2 percent). Readmission rates for AMI within 60 days did not vary based on the proportion of imaging.
They wrote that research in neuroimaging has shown variation was especially high in clinical scenarios that are not well addressed in guidelines but much less variable in subgroups where guidelines are well established. “In comparison, clinical guidelines do not clearly identify which patients among the heterogeneous group presenting with suspected myocardial ischemia should receive cardiac imaging,” they observed.
The authors explained that their study shows that the likelihood of a diagnostic strategy depends on the particular hospital, but “additional work is necessary to understand the organization, cultural and financial aspects of hospital practice that may influence imaging decisions” and can help determine ways to reduce the number of patient tests that may not lead to better outcomes.