This is a rather curious study I’d never specifically see coming, which makes it potentially brilliant. We in Emergency Medicine identify our non-STEMI patients, tidy them up for admission, and bid them bon voyage. We assume their post-Emergency Department care will include non-urgent coronary angiography, and this will properly address their underlying anatomic cause.
It turns out, this may not be the case more frequently than I would have thought. This is a very interesting study in which a convenience sample of patients with non-STEMI were recruited to undergo a cardiac MRI prior to coronary angiography. Cardiologists performing the angiography were blinded to the cardiac MRI results. Following angiography, the cardiologists would identify the culprit artery, if there were one, and its associated infarct territory on an anatomic model. These results were then subsequently compared to the results of the cardiac MRI.
There were 114 patients who underwent MRI and coronary angiography. Of these, angiography identified a culprit lesion in 72 (63%). Of these, 47 were consistent with the ischemic region identified on MRI. The remainder found either a different infarct artery on MRI (10), a non-CAD diagnosis such as myocarditis (9), or no apparent ischemic hyperenhancement (6). In the remaining 42 (37%) who did not have a culprit identified on angiography, 25 of these had an ischemic territory identified on MRI, while the others had a non-CAD related diagnosis or did not find hyperenhancement. Effectively, as compared with the MRI results, the coronary angiography accurately identified a culprit or lack of culprit in 62 of 114 (54%) of cases.
There are many limitations to this article – the least of which being an author is an inventor on the patent of delayed-enhancement MRI, and holds at the minimum a professional conflict of interest in showing this technology adds value. It is non-obvious this cardiac MRI technology should be considered the “gold standard” for identification of the culprit lesion territory, or that their methods of collecting culprit lesion infarct territory is reliable. Finally, this is a small sample from just three institutions and may not be generalizable.
If these data are valid, however, it certainly raises significant issues for many studies featuring revascularization as part of a composite “major adverse cardiac events” endpoint. Frequently, much of downstream MACE consists of coronary revascularization – for good or ill – and these data might further cast doubt upon the accuracy and effectiveness of revascularization. One could imagine an MRI might even be a necessary step in evaluation of non-STEMI to avoid unnecessary or erroneous coronary intervention.
Thought-provoking, but certainly far too early to suggest change in practice.
“Identifying the Infarct-Related Artery in Patients With Non–ST-Segment–Elevation Myocardial Infarction”
https://www.ahajournals.org/doi/full/10.1161/CIRCINTERVENTIONS.118.007305