Pervasive use of CT coronary angiography has been an unnecessary feature of the evaluation of patient with low-risk chest pain for the better part of a decade now. The argument behind its use – a normal examination confers a durable protective effect – is obviously nonsensical, as this bestows agency upon the test itself. Obviously, in a low-risk population with rare adverse outcomes, there can be no reasonable expectation of value in testing.
The sensible idea, then, is to use CTCA in those patients at intermediate risk. In this trial, the stratification used was GRACE score, and the 1,748 participants in this trial were a mean of 62 years of age, and a GRACE score of 115 (SD ± 35). Patients were eligible by symptoms of an acute coronary syndrome, supported by ECG changes, an elevated troponin, or a history of ischemic heart disease. Patients were then were randomized to receive CTCA in the ED or “standard of care only”. The primary outcome was, naturally, the glorious typical cardiology trial outcome of death or non-fatal myocardial infarction at one year.
Over half of patients included demonstrated troponin levels exceeding the 99th percentile, nearly two-thirds had an abnormal ECG, and a third had known coronary artery disease. Approximately a quarter had previously undergone angiography, with a number also receiving PCI. The vast majority presented with chest pain as their initial complaint.
Most patients randomized to CTCA underwent CTCA; a small number of those randomized to standard care also underwent CTCA within 30 days, as well. About a quarter of patients in this cohort demonstrated normal coronary arteries – a fairly surprising development considering the combination of age, risk factors, elevated troponin, and abnormal electrocardiogram necessary for inclusion. Most patients with normal coronary arteries were predictably managed by medical means alone. The remaining patients demonstrated either non-obstructive coronary disease or obstructive coronary artery disease, with concordant trends towards subsequent invasive coronary angiography.
However, after all of that, even with the added information provided by CTCA, there was no difference in mortality or non-fatal myocardial infarction at one year. Delving into the complexities of subsequent resource utilization, it was noted patients undergoing CTCA were less likely to ultimately undergo invasive coronary angiography, 54.0% vs 60.8%. Similarly, patients with the initial CTCA were less likely to undergo subsequent non-invasive testing, 19.4% vs. 26.2%. Other differences in medical or preventive management did not differ by study arm.
So, a small decrease in invasive testing counterbalanced by the large baseline investment in non-invasive testing – without any clear patient-oriented benefit on health outcomes. CTCA certainly has a role in the evaluation of patients with chest pain and possible CAD, but certainly not as a routine investigation in the ED.
“Early computed tomography coronary angiography in patients with suspected acute coronary syndrome: randomised controlled trial”
https://www.bmj.com/content/374/bmj.n2106