Several times recently on wards I have mentioned a research study under review presenting data that in patients with acute coronary syndrome, the final chart diagnosis of STEMI versus NSTEMI correlated more closely with whether they made it to the cath lab in time to satisfy the applicable metric (120 minutes door to balloon time) than it did the ECG findings. The paper was finally published and I am presenting it here:
This is an observational study drawn from a large database of patients who underwent coronary angiography in an acute setting. 410 patients found to have acute coronary syndrome met the eligibility criteria for the analysis. The findings, from the abstract of the paper:
Results: Among 410 angiographed AMI patients (mean age 63 ± 13; 71% male), 165 (40.2%) received an FDx-STEMI and 245 (59.8%) an FDx-NSTEMI. D2B time showed 94% agreement with FDx (160/165 FDx-STEMI treated less than 120 min; 225/245 FDx-NSTEMI treated greater than 120 min), exceeding concordance for STE (82%; p less than 0.001) and TIMI 0-1 flow (75%; p less than 0.001). FDx and STE diverged in 75 patients (18%): 60 rapidly treated STE-negative cases were labelled STEMI, whereas 15 delayed STE-positive cases were labelled NSTEMI. In regression analysis, D2B less than 120 min remained the sole independent predictor of discordance (adjusted OR 6.7, 95% CI 3.5–13.8). Conclusions: In this registry, the cath-lab label “STEMI” showed the strongest correlation with meeting a 120 min benchmark, exceeding correlations for STE or angiographic occlusion. These findings suggest that quality-metric compliance, rather than electrocardiographic or anatomic criteria, predominantly drives final diagnosis.
Here is a graphic that summarizes the findings:
Or, better yet, this cartoon (not from the paper):
The authors elaborate in the discussion section:
Our multivariable analysis asked a specific question: what factors explain the 18% of encounters in which the cath-lab label contradicts the patient’s ECG? Overall, door-to-balloon time less than 120 min was far more concordant with the final cath-lab diagnosis than either guideline ST-segment elevation or angiographic TIMI 0-1 occlusion (94% vs. 82% vs. 74%). This observation answers our prespecified question and underscores that, in routine practice, the label applied in the cath report aligns most closely with the treatment timeline recorded in the electronic chart. This suggests that the designation of STEMI is not always a reflection of the original diagnostic framework, but rather a retrospective label influenced by procedural outcomes and time benchmarks.
The authors believe the findings are generalizable, reflecting trends across the U.S.
They conclude, at the end of the paper:
In this retrospective analysis, time to treatment showed the strongest association. in final diagnosis of STEMI vs. NSTEMI, more important than both STEMI millimeter “criteria” and the presence or absence of total coronary occlusion. This has implications for research and quality improvement.
By the way, the 2025 guidelines for acute coronary syndrome are now published. (They’re fairly new, although they've been online since February of this year). You can access them here:
2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes
There's a growing and now overwhelming body of literature calling for a replacement of the STEMI/NSTEMI paradigm. Despite that, the new guidelines, unfortunately, stick with the existing classification scheme and do not mention the emerging OMI/NOMI concept. There is passing mention in the body of the guideline of a couple of electrocardiographic patterns that are diagnostic of acute coronary occlusion but do not meet STEMI criteria (DeWinter pattern and hyperacute T waves). Because the classification remains in current guidelines this will unfortunately drive MKSAP and ABIM board exam questions for some time to come. So you need to know them while recognizing their deficiencies. In this respect the guideline is 10 years or more out of date. In multiple other content areas there is a world of good information and it is worth the read.
Why this inertia? One big reason is that the STEMI/NSTEMI paradigm is so entrenched in the administrative and coding world. In addition, a reasonably intelligent junior high student can be trained to use a ruler or count a little boxes and measure the degree and direction of ST segment displacement. The new paradigm requires actual skill in electricardiography. I think the cartoon below illustrates the problem well:
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