A patient with no past history of CAD presents with new
symptoms suggestive of cardiac disease. Should we get a CT angiogram (CTA)
anatomic test or a functional test such nuclear stress testing, stress ECG or
stress echo? Which test is better?
An even more difficult question is how do we measure which test is better? Should we focus on
detection of CAD or should we look for outcomes that truly matter and are patient oriented? This is a difficult
question to answer. At least these authors tried.
This study randomized 10,003
office based patients mostly in the USA
to either initial anatomic or functional testing. The composite primary outcome
measure was death, MI, hospitalization for unstable angina, major procedural
complication, foot fungus and priapism. Ok, maybe not the last two.
Even with huge statistical power, there was no difference between the two groups.
Both had very low rates of the composite outcome at 3% over a median follow up time of two years. However, more
patients in the CTA group underwent revascularization 6% vs. 3%. Some would
call this a 100% relative increase.
Does anatomical testing (CTA) find more false positives (overdiagnosis)
and as such result in morbidity & increased cost from unnecessary treatment?
I think these are reasonable questions.
In the end, the vast majority of these patients did just
fine. This could be a reflection of the low risk patients in the USA that get
included in such studies. The initial tests were positive for CAD in only about
10% of this study population.
How can this help us
in the Emergency Department? I’m not so sure. But it is a great study that
demonstrates an emphasis on patient oriented outcomes rather than simply looking
at test characteristics.
The initial investigation of patients with suspected cardiac
disease is high risk. I would
imagine that doctors will be following local convention and protocol rather
than contemplating philosophical matters at the bedside. This is just my
opinion, so perhaps I’m wrong... comments?
Covering:
Douglas PS, Hoffman U, Patel M, et al. Outcomes of Anatomic
versus Functional Testing for Coronary Artery Disease. N Engl J Med 2015;372:1291-300.
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