In the Emergency Department, that is, at least.
A few years ago, there were several major studies evaluating the safety of a CT coronary angiogram-based study for the evaluation of chest pain in the Emergency Department. These studies consistently found the CTCA is sensitive for coronary artery plaque – and, thus, patients with troponin-negative chest pain syndromes and clear coronary arteries could be discharged from the ED.
The constant challenge, however, has been specificity – not only with respect to whether the CT can accurately detect stenoses, but the clinical relevance of the stenoses. Non-obstructive, moderate, and high-grade stenoses detected on CTCA all trigger further evaluation – either non-invasive or invasive, with subsequent interventions of uncertain clinical value.
This small propensity-matched study from a cohort of 25,251 patients undergoing CTCA picked out 234 pairs of patients, matching those who had an acute coronary syndrome during follow-up with those who did not. And, yes, those with ≥50% or ≥70% stenosis were more likely to suffer an ACS, but not my much. The vast majority – 62% – of those with an ACS in follow-up had non-obstructive coronary disease. Indeed, just over half of patients with an ACS even had their culprit lesion identified on the initial CTCA. The degree of stenosis was mildly predictive of future ACS, but plaque burden between those who suffered an event and those who did not was similar. The most predictive feature, however, was composition of non-obstructive plaque, including fibrofatty features and necrotic core.
This is why CTCA is unhelpful in the Emergency Department. It does, yes, accurately detect patients without coronary disease – but this target “low-risk” population already has such a low pretest likelihood of poor outcome the added value is nil. Then, the “true positives” from these studies – stenoses and interventions – are not equivalent to ACS prevented.
Friends don’t let friends do CTCA in the ED – it doesn’t add value or prevent adverse outcomes.
“Coronary Atherosclerotic Precursors of Acute Coronary Syndromes”