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?
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.