CT coronary angiography has been touted as a lovely test for the acute setting – a relatively fast, non-invasive method of obtaining information on the coronary vasculature with reasonable-sounding diagnostic characteristics. However – despite what these authors seem to be trying to convey – it’s simply a test, not a protective intervention.
This is a prospective longitudinal cohort study of 585 individuals at a single institution undergoing CT coronary angiography for suspected ischemic chest pain. Patients with negative troponins were enrolled during weekday, daytime hours, had TIMI 0-4 (mostly 0-2), and absent the usual contraindications to CTCA. Patients were followed for nearly two years – and, of 506 patients with zero or insubstantial plaque seen on CTCA, all were still alive, and none had suffered an acute coronary syndrome. Thus, the fantastic protective effect of a negative CTCA.
The only issue – all those patients would have achieved such event-free survival whether they underwent CTCA or not.
Of the 79 admitted for invasive angiography with severe stenosis, only 34 received PCI or CABG, and 10 were found to have less than 40% stenosis. So – ultimately – 585 CTCAs to identify the 6% of patients who may potentially have benefited, harming just as many with invasive procedures and the remainder with radiation. There is a reasonable, ultimate question regarding whether those with negative evaluations are obviated from additional chest pain work-up over the long run – but that has yet to be demonstrated in practice, and the costs associated with the initial false positives subtract from those future potential savings.
Rather than demonstrate the utility of CTCA in the Emergency Department, these authors better demonstrate the unfortunate characteristics of its overuse.
“Long-term Outcome after CT angiography in Patients with Possible acute coronary syndrome”
http://www.ncbi.nlm.nih.gov/pubmed/24738614
Perhaps the title should really be "Long-term Outcome after CT angiography in Patients WITHOUT an acute coronary syndrome".
And, as I allude above, PCI is really a surrogate marker for a patient-oriented benefit – as we've all seen, once you're in the lab, the cardiologist can't stop himself from stenting _something_.
I still think CTCA has a role. However, we obviously need to find something in common for the 94% of patients with no significant disease to use as a gatekeeper to prevent them from undergoing additional testing.