Author + information
- Stephen Cookson, MBBS, BSc⁎ ( and )
- Mohammad Sahebjalal, MBBS, BSc
- ↵⁎Cardiology Department, University Hospital Southampton, Tremona Road, Southampton SO16 6YD, United Kingdom
Hachamovitch et al. (1) reported increased referral rates for coronary angiography in patients with an intermediate to high probability of coronary artery disease following coronary computed tomography angiography (CCTA) as compared with myocardial perfusion imaging (MPI). Several hypotheses for this discrepancy were offered. Although these may well be correct, the fact remains that these 2 tests are fundamentally different and provide different information; we suggest that it is this difference that drives the increased referral rate seen for CCTA.
CCTA is an anatomic test that provides information about the presence, location, and severity of a stenosis but does not offer the ability to determine whether the stenosis is responsible for ischemia. MPI is a functional test offering little in anatomic data but providing clarity on the presence or absence of ischemia.
A patient with multiple risk factors presenting with angina (as in >75% of the study population) who has a reported 65% left anterior descending artery stenosis on CCTA would be deemed to have a mild abnormality in the study. However, once these anatomic data are obtained, we feel it would be difficult for the clinician to ignore this finding, and hence further investigations (likely angiography with a view to possible stenting) would be requested. However, such a stenosis may not be flow limiting and responsible for ischemia and may not be demonstrated on MPI. If it is demonstrated that the ischemic burden may be low, further tests may be unnecessary. We believe it is this that accounts for the increased referral rates seen.
Before requesting a test, clinicians must decide whether they are seeking anatomic or functional data.
- American College of Cardiology Foundation